Mauerlat is one of the main elements of the roofing structure. The rafters are attached to it. The service life of the entire roof depends on the quality of the truss structure.
Knots for supporting rafters on purlins and mauerlat.
Basic methods of supporting rafters
There are several technologies for supporting rafters on the Mauerlat. The structure can be rigidly fixed. It does not allow any displacement of the rafter leg. To do this, you should use a hemming beam, which prevents the rafters from slipping at the point of support, and metal corners, which eliminate any lateral shift of the structure.
The sliding connection of the rafter leg is used in wooden houses. Moreover, the main element for its support is the upper crown, and not the Mauerlat. To prevent damage to the roof, the rafter support unit is made as free as possible. To do this, you should use a sliding support, which, when the log house shrinks, is displaced along a guide attached to the leg.
The sliding support unit can be made using a different technology. A notch is made in the rafters, which should be adjacent to the upper crown of the log house. To fix the beams, it is permissible to use any fastening elements: staples, nails or steel plates.
Fasteners for installation work
Supporting attachment point for the diagonal rafter leg on the Mauerlat.
To efficiently connect the rafter assemblies with the Mauerlat, you will need the following materials and tools:
- dry timber;
- boards;
- axe;
- hacksaw;
- hammer;
- roulette;
- plumb line;
- level;
- screwdriver;
- drill;
- Bulgarian.
Particular attention should be paid to the presence of all fasteners. The beam consoles are fixed using galvanized steel beam brackets, which do not reduce the load-bearing capacity of the structure. There is no need to embed the brackets into the beams.
You also need to buy perforated mounting tape, which will strengthen the Mauerlat nodes. With its help, a strong connection of all structural elements is made. The tape also does not cut into the beams. To securely fix it, nails and screws are used.
In addition to brackets and perforated tape, to securely support the rafters to the mauerlat, you should purchase:
Scheme of fastenings of layered rafters.
- universal timber connectors;
- fasteners for rafters;
- embedded supports;
- wire rod;
- steel corners;
- rack mounting;
- self-tapping screws;
- nails;
- staples;
- plates;
- galvanized nails;
- studs with washers and nuts;
- anchor bolts.
Creating a ridge and installing the bottom of the rafters
Installation work begins from the ridge part of the roof structure. You can install rafters in one of three ways:
- end-to-end;
- for a run;
- overlap
Joining a structure end-to-end involves cutting the upper part of the rafter leg. This is done at an angle that is equal to the slope of the roof slope. On a skate, a pair of legs is connected. To obtain the same support unit for the Mauerlat elements, you should use a ready-made template.
A special feature of fixing the rafters to the purlin is the presence of a ridge beam. This option for arranging the Mauerlat is characterized by increased reliability. But often such a rafter support system involves the installation of additional supporting structures, which will lead to a decrease in the functionality of the attic. Naturally, this method is not suitable for small roofs.
Supporting the layered rafters on the wall with an armored belt.
The technology for installing overlapping rafters is in many ways similar to installing them on a ridge girder. The main difference is that the upper part of the legs overlaps. This leads to a strong connection of the structure, since the studs hold two elements at once.
The connection of the lower ends of the rafters is carried out depending on the material of the walls. In the presence of wooden house construction, the upper frame of the wall can act as a supporting element. If foam blocks (or aerated concrete) were used during the construction of the house, then the rafters are supported on the mauerlat.
The construction of a reinforced concrete belt is the optimal solution when using masonry building materials. This technology does not provide for the creation of any methods of fixing the rafter system. Vertical anchor bolts serve as fastening elements for the timber. The main thing is that when pouring concrete mortar, the studs are located in a strictly vertical position.
Connection of rafters with beams and mauerlat
After fixing the top and bottom of the rafters, they should be secured to the beams. It is clear that you can connect the rafters to the beam simply with nails. But this is not the best solution. Such a mount will not be as reliable as possible. To prevent sliding of all elements, the truss structure is fixed to the beams by using “tenon” and “tooth” connections.
If there is a steep roof slope (more than 35º), cutting technology using one tooth is used. A tooth with a spike is made at the bottom of the rafter. The nests created in the beam must have a depth of 30% of the beam thickness. The installation of rafter connections is carried out at a distance of 0.3-0.4 m from the extreme part of the beam. This prevents the beams from chipping as a result of heavy loads from foot pressure.
Scheme of strengthening the rafters with additional struts.
When arranging a roof with a slope of up to 35º, the rafters are installed by expanding the interface area of the main structural elements. Usually the rafter leg is covered with a beam. For this purpose, holes are cut in the rafter leg for two teeth:
- tenon with stop;
- one more emphasis.
The cutting depth when fixing the rafters to the beam is within 30% of the thickness of the beam.
Better connections can be obtained by using bolts or clamps. This technology involves the use of wire loops, with the help of which the unit is fixed to anchor bolts located in the wall of the building.
Supporting the Mauerlat is the most common option for fixing the lower part of the rafters. A cutout is made in the rafter leg of such a size that it can be placed on the Mauerlat without any problems. Otherwise, during operation of the roof, the beam may shift.
In some cases, the Mauerlat must be “equipped” with a reverse notch. It depends on the type of wood from which the timber is made. If hardwood was used for its production, then a slot is made, which, in combination with the notch of the rafters, will create a locking element. When making timber from coniferous wood, a cutout is not required, as it will weaken the structure.
The most acceptable option for a Mauerlat is a rigid connection of the rafter system.
Technology for installing the rafter system to the Mauerlat.
This technology can be performed in one of two ways:
- using hemming bars and corners made of metal;
- by installing saddles on the rafters.
The first option is to use a support beam to place the rafters on the mauerlat. The rafter leg is rigidly supported. Reliable fixation of the structure is carried out with metal corners. This prevents lateral movement of the structure.
The second option is more popular. For fastening, nails are used, which are directed towards each other and driven in at an angle. Two hammered nails cross. Then another nail is driven in. The third nail should be in a vertical position. The made fastening unit will be characterized by maximum rigidity if additional fastening is carried out using wire rod.
Rafters are the load-bearing elements of the roof. Mauerlat, the basis of the rafter system, a kind of foundation for the roof structure. Proper fastening of the rafters to the mauerlat ensures the reliability of the entire structure, eliminates deformation of the rafter system, and prevents the roof from collapsing under the weight of an external load.
Mauerlat - correct installation
The Mauerlat, which is essentially the foundation of the roof, is made of logs or timber, laid along the perimeter, and is intended to ensure uniform transfer of the load of the roof structure to the walls and foundation of the building. In order for the roof to stand firmly, the rafters must be properly fastened to the mauerlat.
Important! In a wooden house made of timber or logs, the upper frame of the walls, the upper crown, serves as the mauerlat; no additions to it are required. In a house made of brick, foam or aerated concrete blocks, or building stone, a mauerlat must be installed.
Brick or block walls do not react well to undistributed loads; the blocks or bricks themselves are a poor material for fixing rafter legs. Even the most reliable fasteners are not firmly fixed in such walls; under load they can be torn out, resulting in deformation of the rafter leg and the entire roof.
The Mauerlat should be firmly attached at the upper ends of the walls along the entire perimeter to an equipped reinforced concrete belt. Attaching timber to concrete can be very reliable if the correct fasteners are used. Installation is in progress. It consists of pins, studs, anchors, embedded in concrete on which they are then made.
Important! The ends of the fastening pins should be bent from below, the distance between them is 1-1.5 m, the diameter of the fastener should be at least 15 mm. In the timber that will be used as a mauerlat, make technological holes for fasteners and secure the top of the fastening with bolts. Before installing the Mauerlat, lay a layer of waterproofing material. 
After the base is installed, you can begin to work with the rafters.
Overview of fastener types
Fastening during any work related to the construction of a roof is a very important point. To attach strong and reliable rafters to the mauerlat, various metal fasteners are used, and also different geometries of inserts and cuts are used. For rafter fastening the following are used:
- wire;
- corner;
- plates;
- brackets;
- LK elements;
- nails;
- self-tapping screws
And much more from perforated tape to studs. The use of one or another type of fastening requires different installation techniques.
If the rafters are fastened to the mauerlat using brackets, no cuts are required; if the LK fastening is used, anchors are not needed. The use of perforated tape makes the connection unit super-strong. Fastening with an angle is the most popular and in demand, since it does not need to be cut into the wood of the rafter leg; the angle is easily mounted with self-tapping screws. 
Important! You can't skimp on fasteners. It must be of high quality with an anti-corrosion top layer, galvanized. Fasteners that rust in a beam destroy it.
Principles of connecting rafter legs to the Mauerlat
The design features of the roof determine how the rafters are attached to the mauerlat. Spacer rafter structures, as well as those in which spacers are not used, rest on the Mauerlat. Slab and hanging rafters can rest on it; the connection can be rigid and sliding.
A rigid connection is such a connection between the rafter legs and the Mauerlat, in which shifts, displacements, and bends of the elements are impossible. The immobility of the connection is achieved by fastening using a corner. A saddle is cut out in the rafter leg, this reduces the strength, so it is additionally reinforced with brackets, tightened with bolts, and also the rafter attachment point is connected to the Mauerlat by twisting wire at the locations of the anchors embedded in the reinforced concrete support. 
A sliding fastening, a slide for rafters to the mauerlat, differs from a rigid fastening in that it allows some displacement of the rafter leg relative to the base, this avoids deformation and failure of the roof during shrinkage, snow and wind loads. 
Important! If during the installation process of attaching a rigid type of rafter leg to the mauerlat it is necessary to make a nest or notch, such elements should be made on the rafter, and not on the mauerlat. The foundation cannot be weakened.
Proper support of the rafter leg with the Mauerlat ensures the reliability of the roof and its durability. With any method of support, in order to fix the rafters on the mauerlat, it is important to observe three fundamental points:
- correct and precise making of cuts, cuts, etc., for a perfect fit of the elements;
- the use of washers, nuts, and groovers to prevent the fastener from sinking into the wood;
- It is unacceptable to use pads that can change shape over time, which will lead to load redistribution and destruction.
Correct installation of the roof support system guarantees its longevity.
Types of connection of rafters with Mauerlat
The rafter system consists of many elements, but the main ones are the rafters.
Important! How to attach the rafters to the mauerlat depends on what kind of rafters are used (sloping, hanging), on the loads and how massive the roof is.
The fastening can be sliding and rigid, closed and removable.
The most used connection of rafters with Mauerlat:
Installation of rafters on the Mauerlat is carried out using improved corners KR1, KR2. Their design provides technological holes for anchoring. The oval shape of the holes reduces the risk of the anchor bolt being pulled out when the wood base of the structure dries out. Also reliable are the corners KR5, KR6, which are needed to attach the rafters to the Mauerlat under heavy loads of a massive roof. It is better to securely fasten the rafters to the mauerlat, if they have a large cross-section, with perforated corners of the KM. This fastening is very reliable, no insertion is required, but an exact angle is required.
Important! For fastening at right angles, a reinforced KMRP corner is used; it differs from conventional corners by an elongated hole, it is used to compensate for roof displacement, it is made in such a way that during such processes no damage to the fastening elements occurs, it is especially suitable where it is impossible to insert one part into another. The corner is made of durable steel 2mm thick. 
Another type of connection is installation between boards. The boards are fastenings; they are cut at the desired angle and fixed at the bottom with corners.
Methods of fastening rafters using board linings, twisted wire, staples, to the Mauerlat are also used. These types of fastenings have been known for a long time, are popular and economical. 
Types of rafter supports on the Mauerlat
Mostly gable roofs are erected for residential buildings. With a gable structure, special attention is required to the support of the rafters on the mauerlat. It is clear that a wooden base requires wooden beams.
Important! Rafters are required to be of the correct shape, without knots, calibrated and milled on all sides. The cross-section of the gable roof rafters is 40x150mm, the Mauerlat is 100x100mm.
The choice of fastening type depends on the geometry of the gable roof. You can fasten the rafters using all the methods listed above. It is also worth considering the hinged attachment points of the rafters to the Mauerlat.
A hinge joint is a type of connection that allows a beam to move in a circle. This happens with the help of one nail or self-tapping screw screwed into the Mauerlat. There is a node with one, two and three degrees of freedom. A unit with two degrees of freedom allows the beam to move horizontally; the rafters are secured with slides. With three degrees of mobility, the unit is installed using a slider, a special support for sliding the rafters in a vertical, horizontal position, in addition, the rafter can rotate in a circle. For this purpose, a special hinge is made, which is attached to the base.
Important! The most typical method for a gable roof is to use a zero-freedom assembly. The rafter is fastened with corners on both sides, remaining motionless.
The complex geometry of a gable roof requires the use of layered and hanging rafters. Beams supported on a base are effectively secured using perforated tape.
Layered rafters rest on the base and other support points, thereby relieving part of the load. Side posts can be adjacent to them, ridge headstocks, rafters tighten the structure, strengthening it. Layered structures do not rest on the base, but slide along it. Hanging rafters do not rest on the base; hanging over the interior of the roof, they are supported by the side load-bearing walls. 
Basic rules for pairing rafters with the Mauerlat
For a reliable connection, you need to carefully fasten the connecting elements and select them of the required sizes. It is necessary to accurately check the cuts, making them no more than a third of the size of the base. Use high-quality timber for the base of the correct section.
Important! You cannot use only nails and self-tapping screws for fastening; such fixation cannot be considered reliable; metal fasteners of various types should be used.
The roof will be strong and durable if the calculations are carried out correctly, the material is selected correctly and the joints are installed correctly.
- Hinge joint with one degree of freedom implies the ability to rotate a wooden or metal beam in a circle. This property is possible when attaching the beam to the mauerlat using one screwed-in nail or self-tapping screw.
- Hinge joint with two degrees of freedom allows the beam to rotate in a circle or move slightly in the horizontal direction. To give such freedom to the movement of the beams, you need to fasten the rafters to the mauerlat by installing a slide or securing the rafters with the usual fastening angles, creating a sliding support - a slider.
- Hinge joint with three degrees of freedom ensures the movement of rafters in both vertical and horizontal directions; fastening the beam does not interfere with its circular rotation, as in the two previously listed degrees of freedom. To make such a fastening, it is necessary to make an exclusive hinge that will be screwed into the Mauerlat.
- Node with zero degree of freedom- This is the most common method of fastening rafters in brick buildings. Both ends of the beam are firmly secured with construction angles and self-tapping screws on both sides. This method of fastening does not allow the beam to move.
This video shows one of the options for sliding rafter fastening to the Mauerlat.
Attaching the rafter leg to the mauerlat
Correct marking and calculation of the roof frame in the drawing, and then the quality implementation of the plan in the roof structure is of great importance. Every year, the roof of a building is regularly exposed to the risk of damage to the integrity and even deformation of adjacent walls, due to large amounts of precipitation and changes in temperature conditions. In addition to external risk factors, the base of the roof and walls must withstand the considerable weight of the frame and coverings.
The multi-level roof frame consists of main load-bearing links: rafter legs and mauerlat. Their correct installation guarantees the durability of the roof, the exact location of all ceilings, and therefore the optimal functioning of protective sound insulation, waterproofing, and vapor barriers.
Of all the variety of varieties, we will consider gable roofs, because they are the ones who need a supporting base - a Mauerlat.
To create it, you need to use the material that is planned to be applied to all load-bearing and supporting elements of the frame. If the frame is completely wooden, then the bars for the Mauerlat should also be wooden.
Needs to be taken care of about the correct shape of the beams for the roof base. It is not advisable to use uneven beams with protruding knots. If you are unable to find even beams, make sure that the length of the small branches is not more than one third of the width of the beam. Ideally, all beams are processed and delivered to the roof assembly stage calibrated and milled on at least both sides, and preferably on all four sides.
For the roof frame, and therefore for the mauerlat, iron or reinforced concrete is often used. This frame is highly durable. If, according to your individual calculations, the walls can support the weight of the metal frame, you can choose this option. For the metal frame, Mauerlat blocks of the same material are used.
The dimensions of the beams vary from ten centimeters, usually beams of at least fifteen centimeters are used. The width of the beam directly depends on the length and width of the rafters. For example, if the cross-section of a gable roof beam is 40x150 mm, then Mauerlat beams with a cross-section of 100x100 mm are used. With a timber section of 100x250 mm, a Mauerlat of 150x150 mm is made.
The Mauerlat is attached to the inside of the outer wall using anchors, steel wire or studs. In the process of laying the Mauerlat bars, you need to connect them at all joints with metal staples.
Need to secure the foundation beams as high quality as possible. Rafter legs will be installed on them, the wear resistance and reliability of the entire roof depends on their precise fixation.
Mounting methods
How to attach rafters to the mauerlat? According to the method of attaching the rafters to the Mauerlat roof frames are divided into:
- Layered rafter system.
- Hanging rafter system.
Layered rafters
Layered rafters are classified as non-thrust frame structures, which determines their minimum pressure on load-bearing walls. The support points for layered rafters are the external walls of the building and the vertical posts located in the middle of the roof frame on a pre-installed tie.
Mounting points Layered rafters to the mauerlat are most often made hinged. When using sliders and movable hinges in fastenings, the roof frame can lower by several centimeters. This is necessary for an architectural structure in the first years after construction. When temperature and weather conditions change, the new building shrinks slightly. If the roof does not change its position following the supporting walls, the elements of the building may undergo cracking or deformation, which will not happen due to the layered fastening of the rafters on movable hinges.
Hanging rafters
Hanging rafters are used for buildings that do not have load-bearing walls inside. The support points for hanging rafters are only the external load-bearing walls. The fasteners of such structures are represented by a unit with a zero degree of freedom. Other methods are not available, since fastening the rafters to the mauerlat on the walls is the only support for the entire roof structure.
Hanging rafters- These are spacer structures. Rafters secured in a hanging manner are only capable of exerting horizontal bursting pressure on the walls, but this pressure is very high.
To reduce pressure on beams and walls use crossbars- These are special puffs. They are installed perpendicular to the rafters, closer to the bottom of the structure and are securely attached to each beam, collecting parallel rafters into a single whole. Without crossbars, it is impractical to build a roof with hanging rafters. 
Technologies for attaching a rafter leg to a mauerlat
The connection of the rafters to the mauerlat is made both with the help of cutting, tapping, and sawing, which usually occupy no more than 1/4 of the beam, and without them. Depending on the angle of the roof slopes and the use of the optimal support unit, the method of laying and fixing the beam on the mauerlat is selected.
The photo shows one of the methods of attaching rafters to the Mauerlat.
The elements are fastened using various devices:
- self-tapping screws;
- bolts with nuts;
- corners;
- varieties of corner KR;
- plates;
- wire ties;
- perforated mounting tape TM;
- WB brackets;
- LK fasteners;
Installing rafters on the mauerlat- this is the fastening of the horizontal load-bearing surface of the roof with the vertical one. Proper calculation and installation of all elements of the frame system is important.
Mauerlat - roof foundation. Strong fastening of the junction of the rafters with the Mauerlat guarantees the durability of the constructed roof.
The key to a long and trouble-free life in a newly built house is a durable and safe roof. The basis of its reliability is the correct calculation of all elements of the selected rafter system and well-executed installation. The quality of installation is based on the correct selection of materials, fasteners and methods of connecting all structural components.
Mounting options
The construction of any roof includes several basic elements:
- The rafter frame is the main supporting element of the roof, one might say its skeleton.
- Lathing - ribs for the roof, if we continue the anatomical analogy.
- The roofing package is the top skin covering, following the same pattern.
All types of rafter systems can ultimately be reduced to two main classes:
Hanging rafters
This type of roof structure is formed by a rigid triangular coupling of a truss structure made of rafter boards and a lower tie-beam, which, in turn, rests on the Mauerlat. Such a device creates a load on the walls of the building, which has a predominantly vertical component.
Hanging rafter construction
Mauerlat is a thick support beam, tightly fixed at the top of the wall and serving as the base, and in fact the foundation, for the rafter frame. It plays the important role of uniformly distributing along the walls of the house both static loads from the weight of the roof and the equipment on it, and dynamic influences from snow, wind, the weight of people working on the roof, etc.
Hanging type rafter systems can be held in place only by their own weight, and their additional adhesion to the wall is performed solely to compensate for shear forces under significant wind loads. It is ensured by fastening the lower beam-tightening of the hanging rafters to the mauerlat and, without presenting much technical difficulty, can be performed with any available fasteners: staples, squares, nails, clamps, etc.
Layered rafters
Construction with layered rafters
Layered rafters are a roofing option when the rafter beams lying at an angle have two support points at their ends: the mauerlat and the ridge beam. The latter, in turn, rests through intermediate posts on the internal wall of the house or on a thick longitudinal beam - “matitsa”.
A layered rafter system has a more complex distribution of loads: in addition to the vertical “gravity”, there are also “sliding” horizontal and “expanding” angular components.
Due to the complexity of the triangle of forces, their compensation should be ensured by a reliable connection of the rafter legs with the mauerlat.
Support units and their fastening
One of the features of a layered rafter frame is that its elements can have both fixed and movable hinge joints between them. All three fixed frame units are usually used in brick or stone houses, where they are given additional rigidity by the strong walls of the building.
Attachment points for rafters to the Mauerlat
The connection of the upper ends of the rafter boards with the ridge or the lower ends with the Mauerlat, or both together, is often made hinged and movable. This is necessary to reduce internal stresses occurring in the rafter frame, which may be caused by:
- temperature fluctuations;
- house settlement;
- deformations of wooden structures, such as torsion or bending;
- uneven loads from wind and snow.
If it is not very convenient to work under the ridge at a high height when installing the fastening, then it is better to choose a rigid connection for the rafter boards at the top. For their lower ends, leave a little freedom of longitudinal movement.
Attaching the rafter leg
The lower assembly of the rafter support on the mauerlat is usually performed in one of two ways:
- Spacer- a variant of a fixed lower clutch unit, when the rafter rests rigidly on the beam.
- Sliding- a movable connection in which the rafter slides along the beam, being held on it only by fasteners.
Both of these methods are widespread and have their own characteristics and variations.
Fastening methods with and without sawing
The joint without a gash is used only with a sliding connection. The rafter leg rests freely with its lower edge on the mauerlat, held only by fasteners, which are most often used as corners. This fastening option cannot be called absolutely reliable under significant loads from the roof, so it is used mainly to cover small spans.
For a more reliable articulation of the elements of the lower assembly, a blocking tooth is cut out in the rafter board. It can be done in the following ways:
- With emphasis on the inside of the Mauerlat, forming a rigid mount that works under compression.
Focusing on the inside
With nailed board
In most cases, the sawing must be done in the rafter board, and not in the mauerlat, so as not to weaken or deform it.
Rafter fasteners
In the recent past, traditional staples and nails were used as fasteners for elements of roof frames, and in the simplest case, ordinary wire rod folded in several rows. Today on the construction market you can find various types of fasteners for any application. Specialized kits for use in rafter systems are also produced by industry.
To avoid being pulled out, nails used in joints should be twisted or with a special notch.
Rules for performing work
- The rafter leg blank must be placed with its upper edge on the ridge beam, and its lower corner must be aligned with the inner edge of the mauerlat beam.
- Using a piece of board that serves as a template, draw a line on the rafter parallel to the top edge of the mauerlat.
- If necessary, mark the persistent saw tooth on the outside or inside.
- Cut along the marking lines.
When making cuts, it is necessary to strictly observe the measured and marked angles for a tight fit of all planes of the wooden structural elements.
- Place the rafter in its place, carefully aligning all the cuts.
Secure it using the chosen fastening method. Each fastening method has its own characteristics for proper execution:
- The nails are driven at an angle through the rafter board into the mauerlat, two on each side.
Now “sled” corners with a sliding plate have appeared on sale especially for rafters. They provide a reliable connection with full compensation of deformations.
After installing the lower assembly of the rafter leg, you can begin pairing it with the ridge beam.
The construction of the roof takes almost half of the entire time of building a house. And the material costs for it are about the same. At the same time, the smallest errors made during the design and construction of the roof can become a source of significant problems during its operation.
When starting this important and complex stage in construction work, it is necessary to carefully and repeatedly check all outlines and calculations. It’s a good idea to consult with experts or refer to reference publications.
Methods of attaching rafters to the Mauerlat: installation technology with and without sawing
The connection of the rafter legs with the Mauerlat has many subtleties. But the strength and reliability of the entire future roof depends on them. What methods of fastening are there?
Types of fastening rafters to the Mauerlat without sawing
The rafter leg is the main load-bearing element of the pitched roof frame. The strength and durability of the entire structure depends on the correct fixation of the rafters. The most commonly used roof system is when two rafter legs are connected at the top point on the ridge, and the lower ends are supported and fixed on the mauerlat beam. There are different options for attaching load-bearing rafter legs to this horizontal beam. In our article we will look at fastening rafters without sawing.
Types of fixation
The choice of method for attaching the rafter element to the mauerlat depends on which rafter system (inclined or hanging) is used, as well as on the weight of the beam, the complexity of the structure and design loads. To begin with, it is worth saying that there are two ways to attach the rafters to the mauerlat beam: rigidly or using sliding fixation. Fixation without cutting can be performed using one or another type.
Sliding mount
The sliding fastener consists of two elements. One of them can move freely relative to the other. In addition, the rafters can be attached to the Mauerlat beam in an open or closed way. Let's look at them in more detail:
- With a closed fastening method, a special corner with an eyelet resembling a slot is used. This part is first attached to the Mauerlat. A metal part with holes is inserted into the eyelet. It is through these holes that the corner is attached to the supporting leg. Thanks to the loose vertical surface of the corner, the rafter can move slightly if necessary, thereby protecting the wall structures of the building from excessive load and deformation.
- The open fastening option is carried out similarly, with the only difference that a loop is not inserted into the eye of the corner. The corner is first attached to the Mauerlat, and then the upper part of its shelf is folded down to make the connection.
Rigid mount
If we talk about how the rafters are rigidly attached to the Mauerlat, then there are a greater number of options. The choice of one method or another is made taking into account the installation features of the roof system, as well as the dimensions and weight of the wooden structural elements.
Rafters on a single-pitched roof or multi-pitched system can be fastened using:
- metal corners of different sizes;
- special LK mounts.
The latest version of fastenings is made in any size, which makes it easy to select it to fit the dimensions of the rafters. For the production of these fasteners, steel with a thickness of 2-3 mm is used. Such connecting elements provide maximum rigidity and reliability of fixation.
Important: the corners for connecting rafters to the mauerlat without a cut differ from the corners that are used when fixing with a cut. They have enlarged shelves with a large number of holes for screws. For their manufacture, thicker steel (3 mm) is used.
Other fastening options without sawing
If, when making a pitched roof, it is necessary to ensure high reliability and rigidity of the entire truss structure, then the following fastening option can be used. The supporting leg is installed between two boards, which are sawn from below at the desired angle and additionally secured with metal corners or LK fasteners. This method is used if the rafter leg needs to be fixed with a given slope at a short distance from the surface of the mauerlat. In this case, the fastening is carried out to the outer vertical surface of the beam.
If the rafters are attached to a mauerlat, which is made of small-section timber, then it is reinforced with wooden plates of the required thickness. These pads are attached to the Mauerlat using self-tapping screws or nails only where the load-bearing legs will be mounted. To secure the rafters, strong steel wire is used, which is screwed to a steel spike driven into the wall.
You can also use brackets to connect the rafters to the Mauerlat in single- and double-pitch systems. To do this, you can take staples of different sizes and drive them in any place. This method of fastening is quite common, since it allows you to obtain a durable connection of all elements of the rafter system.
Tip: for additional strengthening of the fastening unit and more durable fixation, you can use perforated TM tape. Sometimes it is simply impossible to do without it.
Another option for fixing rafters without cutting is sometimes implemented without a Mauerlat. In this case, the load-bearing legs rest against the floor beams. If we talk about the option without a cut, then the rafters simply rest against the beam. To connect the elements, bolts and mounting angles made of steel are used.
Selection of fastening depending on the type of system
Depending on the characteristics of the supporting frame of the house and the type of roof, a type of rafter system is selected. In each type of such systems, various additional elements are used (tightenings, supports, racks, etc.).
When choosing a method for attaching load-bearing legs without cutting, it is necessary to take into account the type of rafter system. They are inclined and hanging:
- In inclined systems, part of the load from the roof on the walls is redistributed to additional supporting elements. These can be racks, headstocks, floor beams, tie rods. Most often, a pitched roof is made with this type of rafter system. In this case, it is recommended to use the sliding method to connect the rafters to the Mauerlat. Since in this case the roof structure will be reliably protected from deformations that occur during shrinkage of the building.
Attention: this method of fixation is especially important for recently erected buildings, which will certainly shrink under the influence of soil movements and temperature changes.
- Hanging rafter systems do not use additional supports, racks and other elements onto which part of the load from the roof can be transferred. In this case, the entire load from the roof structure falls on the Mauerlat beam. That is why in these systems it is better to use a rigid connection, which will eliminate the possibility of any movement. To partially compensate for the load on the walls, such systems use tie-downs, crossbars and struts.
Fixation Rules
To obtain a reliable and durable connection of the load-bearing legs with a horizontal beam, it is important to adhere to the following rules:
- When using steel angles, plates and other metal parts, they must be firmly screwed to the wooden elements of the supporting system using self-tapping screws.
- If bolts are used to connect the supporting legs and other wooden elements of the roof frame, then a special washer for the bolt or a metal plate must be used. This will prevent the nut from going deeper into the body of the wood and weakening the load-bearing element of the roof frame.
- Connecting the Mauerlat to the rafters using nails and self-tapping screws alone is considered unreliable. It is imperative to use metal plates and steel corners, which will strengthen the fastening unit.
- In wooden buildings, it is better to attach the legs of an inclined or hanging system to a horizontal beam using a sliding method. This is especially important if the roof is of significant weight, since it will avoid deformation of the roof structure during shrinkage of the building.
As you can see, there are many ways to connect load-bearing legs to a horizontal beam without sawing. When choosing one option or another, it is important to take into account the design features of the structure, the material of the walls, the weight of the roof, the type of roofing, as well as the loads that the frame will bear.
Attaching rafters without cutting to the mauerlat in a pitched roof
Rules for fixing and methods for attaching rafters to the mauerlat without washing down the legs. Sliding and rigid fastening. The choice of fixation depends on the type of rafters.
Methods of attaching rafters to the Mauerlat: basic methods and schemes for attaching rafter legs
Rafters are the most essential part of the roofing skeleton. The legs of the rafters transmit the thrust to the mauerlat and load-bearing walls of the house. What does the quality of the entire rafter system and the roof as a whole depend on? Experts remind that the reliability of any roofing structure will depend, first of all, on the quality of fastening the rafters to the Mauerlat. What principles and features of this process should every novice builder know and how to attach the rafters to the Mauerlat with your own hands, you will learn right now.
Attaching the rafters to the mauerlat: a little “materiel”
To begin with, we suggest looking at an illustration that shows two types of rafter systems:
The place where the rafter leg is attached to the base is called the support node. There are many such units in the system, but we will touch in detail on the lower fastenings of the frame with the rafters. The mauerlat and rafter legs are almost always made of wood, less often - of metal. It is more profitable and convenient to use wood, since this material is light in weight, easy to install and durable with proper installation and operation.
Types of support units by level of rigidity
Support nodes - places where the rafters are attached to the roof elements:
In the case of iron connections, the nodes are fixed and rigid (welded or bolted). Wood is a softer and more dynamic material that can swell, dry out and deform. In this regard, experts recommend making support units with allowances for possible changes in the shape of the wood. Such nodes can have different degrees of mobility:
- Zero mobility node- rigid fastening with corners on both sides, in which the fastening of the rafters to the mauerlat remains motionless.
- Connection of the first degree of freedom– the beam can rotate in a circle.
- Connection of the second degree of freedom– circular rotation with displacement, provision is made for the installation of special sliders or slides.
- Third degree movable joint– possibility of horizontal, vertical and circular movement.
For any node, whether it is movable or not, at least two types of fixation should be used. For example, notched planks are additionally fixed from the inside using a support beam, and dynamic connections are strengthened with bolts and special steel angles.
About the types of fastening of rafters to the base
Let's talk about modern fasteners. For the strength and durability of the support units, a variety of metal fasteners are used: beam holders, equilateral, fastening, anchor, reinforced corners, plates, supports, profiles, connectors, anchors, etc. All these parts are made of high-quality metal. For dynamic units (types 1, 2 and 3), sliders, angles and perforated plates are used. For rigid fastening, stationary connectors, anchors and corners are used.
Such fasteners for the rafter system are most often used:
For self-assembly, perforated fasteners are more suitable than others, since they have many holes for self-tapping screws and bolts.
Rigid or flexible connections: what to choose
So, we noted that the support nodes connecting the Mauerlat to the boards can have different degrees of mobility: from “0” to “3”. Zero degree - these are rigid fastenings that exclude any changes in the position of the beams.
Rigid connections: when they are needed
The Mauerlat is installed when it is necessary to transfer the thrust load from the rafters to the load-bearing walls. This is done mainly in houses made of bricks, panels and blocks. In this case, they try to eliminate deformation and shrinkage of the roof in order to prevent changes in the load on the supporting walls. This is where the need arises for a fixed connection of the rafter system with the Mauerlat.
Fixed units secured with a notch
Many experts recommend making appropriate cuts at the point where the rafters are attached to the floor beams for greater strength and immobility of the connecting nodes. These cuts should fit tightly with the Mauerlat. Additionally, such units are strengthened with bolts, anchors and metal plates:
Or with long screws:
And one more important point: the size of the cut of the bar should not exceed 1/3 of its cross-section. Otherwise, the rafter system may lose its load-bearing capabilities:
Hard knots without notching rafters
The fastening method using a hemming block is used in layered rafter systems. The rafters are cut according to a template and beveled (to give the roof the desired slope) at the point of contact with the mauerlat. From the inside, such rafters are reinforced with support bars and reinforced with corners on both sides to the base frame:
Another option for a non-joint joint is a rigid fastening of the rafters, reinforced with overlay beams on both sides. Two boards at least a meter long border each rafter leg. One end of such supports is cut at an angle that corresponds to the slope of the roof slope (including rafters). The boards are fastened with a cut to the Mauerlat using long bolts and reinforced steel corners. The bars are attached to pre-marked places, first one at a time. Then the rafters themselves are mounted close to the overlays on one side, which are immediately reinforced with the same overlay on the other side. There is an option to install two beams at once, and then rafters, but this method is used less often, since it requires more accurate calculations.
When do you need to make moving connections?
Here we come to dynamic support nodes - connections that can change their position. What is it for? Let's remember the physical properties of materials - many of them shrink or swell. First of all, this applies to buildings made of pure wood - timber, logs, etc. Natural wood necessarily shrinks, due to which your roof can not only be deformed, but also completely collapse. To avoid such fatal consequences, craftsmen recommend sliding fastenings of rafter legs with a mauerlat (or the upper crown of a log house).
A prerequisite when installing sliding units is to support the rafter frame on a strong ridge beam. Since the supporting lower nodes are dynamic, maximum rigidity should be achieved at the roof ridge. The upper edges of the rafters are sawed down for a tight connection between themselves and the ridge beam, connected and reinforced with crossbars, metal strips, plates and corners. It is better to connect the rafter element already fixed in the ridge to the crown of the log house.
What is a sliding mount?
The movable connection is made by installing sliding fasteners called “slides” or “sliders”. Such a unit provides a certain freedom for the rafter legs, which helps prevent deformation of the roofing system after the natural shrinkage of wooden buildings:
Here are the types of sliding supports:
Should I make a gash on the rafters if the house is made of timber: an alternative expert opinion
I still suggest cutting down, but not the rafters, but the top crown. Firstly, in this case, the risk of rafter bending is reduced, secondly, the “cold bridge” is reduced, thirdly, the tangential pressure on the mauerlat (top beam of the log house) is reduced, and fourthly, insulation of the roof in the future is simplified. The disadvantage of this method is that when cutting down the upper crown of the beam, the height of the ridge decreases, therefore, if in the future it is planned to raise the height of the ceiling, one more crown should be provided. But! Such schemes are only suitable for houses made of wood, since in brick and concrete buildings the mauerlat must be intact in order to maintain its load-bearing qualities.
How to properly attach rafters to beams?
In simple houses, mostly frame ones, the Mauerlat can be abolished. In this case, the rafters are attached to the floor beams. The most reliable option for assembling such a system is the preparation of roof trusses. Each truss consists of two rafter legs, a connecting crossbar and a bottom tie. For strength, the trusses are reinforced with central beams and struts:
The floor beams are laid in such a direction that the trusses intersect them perpendicularly in different planes. The tie performs the main load-bearing functions, is attached to the floor beams with anchors, through bolts, studs and reinforced with plates and metal corners.
It is possible to attach the rafter legs directly to the beam, which will additionally serve as a tightening. To create high-quality support units in such a system, two fastening methods are recommended:
- Connecting the rafters to the beam with a double tooth - cuts are made on the beam and the bevel of the rafter leg (two butt notches on each).
- Fastening with bolt and clamp. Through fastening may be provided, but if the boards have a large cross-section, notches are made and the parts are connected with long bolts.
Attaching the rafters to the mauerlat: step-by-step description
As an example, we will describe the process of rigidly attaching rafter connections to the Mauerlat on a simple gable roof.
I. Preparing the mauerlat and rafters for work
At this stage, it is necessary to cut out the rafter legs of a given length and mark their step on the base. The optimal step length of the rafter legs is 60-200 cm. You should also accurately determine the angle of inclination of the rafters.
Master class on installing the Mauerlat:
II. Creating a gash
We make a gash on each rafter leg for a tight connection with the base. To increase strength, you can provide an additional notch on the frame or rafter and install a thrust beam under each rafter leg.
III. Installing rafters on the mauerlat
The rafters must be laid carefully so as not to damage other elements of the building (windows, walls, etc.). We place the boards with a cut on the beams and rest them on the ridge beam. First, we install the outer rafter legs, between which you need to stretch a thread to align all the other rafters.
IV. Fastening each rafter to the mauerlat
Now that all the trusses are in place, you need to firmly secure the support units. For this we use several of the mounts suggested above:
- Nails+ steel corners on the left and right sides of the joints between the board and the base.
- Through bolts or studs+ support beam for rafter bevel.
- Anchors or bolts+ angles or steel plates, etc.
Two overhead boards on both sides of the rafter leg, installed on pre-marked places on the mauerlat, will help to strengthen the fastening. You can also use wire fastening as a strength enhancer for connections. To do this, you need to prepare a steel wire twist of 2-3 wires. Its length should be enough to wrap around the rafter leg at the junction with the Mauerlat and secure the ends of the twist to a metal crutch. As a crutch, you can take a long steel bolt, which is mounted into the wall 30-40 cm below the Mauerlat, strictly under the support unit.
We will also consider one of the old-fashioned methods - fastening with staples:
What is the secret of the quality of the rafter system: three main rules of the master
- High-quality lumber is half the battle on the path to successful construction. The mauerlat and rafters should not have cracks, wormholes or knots.
- The accuracy of measurements, cuts and uniformity of the position of the fasteners is an equally important point. If all the rafter legs are the same length and cross-section, then it is better to prepare a template for making cuts and notches.
- Gaps on the Mauerlat – loss of the load-bearing functions of the base by 50% or more. The percentage of strength reduction depends on the depth of the notches.
When the rafter system is ready, it’s time to install the sheathing, insulation and roofing material. But this is another interesting topic, which we will definitely talk about in the next article. In the meantime, we wish you good materials, easy work and good helpers!
Fastening the rafters to the mauerlat: diagrams and methods of fastening the rafters
Detailed diagrams and methods for attaching rafters to the Mauerlat, step-by-step guides for installing rafter legs and expert advice.
Methods for attaching rafter legs to the Mauerlat
Rafters are the load-bearing elements of the roof. Mauerlat, the basis of the rafter system, a kind of foundation for the roof structure. Proper fastening of the rafters to the mauerlat ensures the reliability of the entire structure, eliminates deformation of the rafter system, and prevents the roof from collapsing under the weight of an external load. 
Mauerlat - correct installation
The Mauerlat, which is essentially the foundation of the roof, is made of logs or timber, laid along the perimeter, and is intended to ensure uniform transfer of the load of the roof structure to the walls and foundation of the building. In order for the roof to stand firmly, the rafters must be properly fastened to the mauerlat.
Important! In a wooden house made of timber or logs, the upper frame of the walls, the upper crown, serves as the mauerlat; no additions to it are required. In a house made of brick, foam or aerated concrete blocks, or building stone, a mauerlat must be installed.
Brick or block walls do not react well to undistributed loads; the blocks or bricks themselves are a poor material for fixing rafter legs. Even the most reliable fasteners are not firmly fixed in such walls; under load they can be torn out, resulting in deformation of the rafter leg and the entire roof.
The Mauerlat should be firmly attached at the upper ends of the walls along the entire perimeter to an equipped reinforced concrete belt. Attaching timber to concrete can be very reliable if the correct fasteners are used. During the process of pouring the reinforced belt, the Mauerlat fastening is installed. It consists of pins, studs, anchors embedded in concrete onto which the Mauerlat is then installed.
Important! The ends of the fastening pins should be bent from below, the distance between them is 1-1.5 m, the diameter of the fastener should be at least 15 mm. In the timber that will be used as a mauerlat, make technological holes for fasteners and secure the top of the fastening with bolts. Before installing the Mauerlat, lay a layer of waterproofing material. 
After the base is installed, you can begin to work with the rafters.
Overview of fastener types
Fastening during any work related to the construction of a roof is a very important point. To attach strong and reliable rafters to the mauerlat, various metal fasteners are used, and also different geometries of inserts and cuts are used. For rafter fastening the following are used:
And much more from perforated tape to studs. The use of one or another type of fastening requires different installation techniques.
If the rafters are fastened to the mauerlat using brackets, no cuts are required; if the LK fastening is used, anchors are not needed. The use of perforated tape makes the connection unit super-strong. Fastening with an angle is the most popular and in demand, since it does not need to be cut into the wood of the rafter leg; the angle is easily mounted with self-tapping screws. 
Important! You can't skimp on fasteners. It must be of high quality with an anti-corrosion top layer, galvanized. Fasteners that rust in a beam destroy it.
Principles of connecting rafter legs to the Mauerlat
The design features of the roof determine how the rafters are attached to the mauerlat. Spacer rafter structures, as well as those in which spacers are not used, rest on the Mauerlat. Slab and hanging rafters can rest on it; the connection can be rigid and sliding.
A rigid connection is such a connection between the rafter legs and the Mauerlat, in which shifts, displacements, and bends of the elements are impossible. The immobility of the connection is achieved by fastening using a corner. A saddle is cut out in the rafter leg, this reduces the strength, so it is additionally reinforced with brackets, tightened with bolts, and also the rafter attachment point is connected to the Mauerlat by twisting wire at the locations of the anchors embedded in the reinforced concrete support. 
A sliding fastening, a slide for rafters to the mauerlat, differs from a rigid fastening in that it allows some displacement of the rafter leg relative to the base, this avoids deformation and failure of the roof during shrinkage, snow and wind loads. 
Important! If during the installation process of attaching a rigid type of rafter leg to the mauerlat it is necessary to make a nest or notch, such elements should be made on the rafter, and not on the mauerlat. The foundation cannot be weakened.
Proper support of the rafter leg with the Mauerlat ensures the reliability of the roof and its durability. With any method of support, in order to fix the rafters on the mauerlat, it is important to observe three fundamental points:
- correct and precise making of cuts, cuts, etc., for a perfect fit of the elements;
- the use of washers, nuts, and groovers to prevent the fastener from sinking into the wood;
- It is unacceptable to use pads that can change shape over time, which will lead to load redistribution and destruction.
Correct installation of the roof support system guarantees its longevity.
Types of connection of rafters with Mauerlat
The rafter system consists of many elements, but the main ones are the rafters.
Important! How to attach the rafters to the mauerlat depends on what kind of rafters are used (sloping, hanging), on the loads and how massive the roof is.
The fastening can be sliding and rigid, closed and removable.
The most used connection of rafters with Mauerlat:
Installation of rafters on the Mauerlat is carried out using improved corners KR1, KR2. Their design provides technological holes for anchoring. The oval shape of the holes reduces the risk of the anchor bolt being pulled out when the wood base of the structure dries out. Also reliable are the corners KR5, KR6, which are needed to attach the rafters to the Mauerlat under heavy loads of a massive roof. It is better to securely fasten the rafters to the mauerlat, if they have a large cross-section, with perforated corners of the KM. This fastening is very reliable, no insertion is required, but an exact angle is required.
Important! For fastening at right angles, a reinforced KMRP corner is used; it differs from conventional corners by an elongated hole, it is used to compensate for roof displacement, it is made in such a way that during such processes no damage to the fastening elements occurs, it is especially suitable where it is impossible to insert one part into another. The corner is made of durable steel 2mm thick. 
Another type of connection is installation between boards. The boards are fastenings; they are cut at the desired angle and fixed at the bottom with corners.
Methods of fastening rafters using board linings, twisted wire, staples, to the Mauerlat are also used. These types of fastenings have been known for a long time, are popular and economical. 
Types of rafter supports on the Mauerlat
Mostly gable roofs are erected for residential buildings. With a gable structure, special attention is required to the support of the rafters on the mauerlat. It is clear that a wooden base requires wooden beams.
Important! Rafters are required to be of the correct shape, without knots, calibrated and milled on all sides. The cross-section of the gable roof rafters is 40x150mm, the Mauerlat is 100x100mm.
The choice of fastening type depends on the geometry of the gable roof. You can fasten the rafters using all the methods listed above. It is also worth considering the hinged attachment points of the rafters to the Mauerlat.
A hinge joint is a type of connection that allows a beam to move in a circle. This happens with the help of one nail or self-tapping screw screwed into the Mauerlat. There is a node with one, two and three degrees of freedom. A unit with two degrees of freedom allows the beam to move horizontally; the rafters are secured with slides. With three degrees of mobility, the unit is installed using a slider, a special support for sliding the rafters in a vertical, horizontal position, in addition, the rafter can rotate in a circle. For this purpose, a special hinge is made, which is attached to the base.
Important! The most typical method for a gable roof is to use a zero-freedom assembly. The rafter is fastened with corners on both sides, remaining motionless.
The complex geometry of a gable roof requires the use of layered and hanging rafters. Beams supported on a base are effectively secured using perforated tape.
Layered rafters rest on the base and other support points, thereby relieving part of the load. Side posts can be adjacent to them, ridge headstocks, rafters tighten the structure, strengthening it. Layered structures do not rest on the base, but slide along it. Hanging rafters do not rest on the base; hanging over the interior of the roof, they are supported by the side load-bearing walls. 
Basic rules for pairing rafters with the Mauerlat
For a reliable connection, you need to carefully fasten the connecting elements and select them of the required sizes. It is necessary to accurately check the cuts, making them no more than a third of the size of the base. Use high-quality timber for the base of the correct section.
Important! You cannot use only nails and self-tapping screws for fastening; such fixation cannot be considered reliable; metal fasteners of various types should be used.
The roof will be strong and durable if the calculations are carried out correctly, the material is selected correctly and the joints are installed correctly.
Fastening rafters to the mauerlat of a gable roof: methods, components, installation
Fastening rafters to the mauerlat of a gable roof and other types of structures with and without a cut. Description of types of fasteners and connections of rafters to the roof base, as well as useful tips.
Experienced builders know very well that during the construction of a rafter system there are no nodes that do not play an important role in ensuring the strength of the structure. This also applies to methods of attaching the rafter leg to the mauerlat. We will not dwell on the characteristics of the Mauerlat itself, the methods of its construction and the methods of its fastening. The initial data for all options for attaching rafters to mauerlats are standard - all of them must be made in accordance with the requirements of existing building codes and regulations.
We need to briefly clarify one more issue - attaching rafters to mauerlats is not always possible.
When and why can’t you use this method of fastening the rafter system?
| On complex hip or gable roofs with different slope angles. | Why? The angle of the rafter (or filly, if it is not long enough) from each roof slope will be different. This means that problems will arise during the installation of the eaves of the roof. If you want to make the width of the cornice the same along the entire perimeter of the building, it will be located at a different height on each wall. If you want to make all the cornices at the same height, then each wall will have a different width. We need to remember our school lessons about triangles. It goes without saying that both the first and second options for the building are unacceptable. On such buildings, the rafter legs should be attached only to the floor beams; this is the only way to make the cornice the same in width around the entire building. And if the roof has a bay window, then it makes no sense to even theoretically consider the option of attaching the rafter legs to the mauerlat. | |
|---|---|---|
| During reconstruction or repair of old or emergency buildings. | Experienced builders immediately determine the slope angles of the slopes. If, at the places where they intersect, the lines of the roofing cover form a right-angled triangle, then the slope of the slopes is the same; if the waves of the covering do not coincide, the rafters will have to be fastened to the beams. | |
| The upper rows of load-bearing walls are in such a deplorable state that it is very difficult to attach a Mauerlat to them with the required strength indicators. | It is necessary either to dismantle several rows of bricks and lay them again or to concrete a special reinforcing belt along the entire perimeter of the building, and only after such work is completed, the Mauerlats are firmly fixed. Practice shows that doing such work is not economically profitable, and it takes much more time than installing load-bearing beams on the ceiling. |
We have dealt with this issue, now we should consider several general recommendations regarding the fastening of rafters.
| Recommendations for fastening rafters | Description | Illustrations |
|---|---|---|
| Rafters should never be sawed or notched deeper than one-third of the width. | Remember this rule once and for all. On the Internet you can find examples of rafters being cut down to almost half the width; this is a gross mistake. One may ask, why take a board 150 millimeters wide for the rafters, and then “cut off” half of it in the most loaded place? What load-bearing capacity will it have left? Moreover, this rule applies not only to the attachment point of the rafters to the Mauerlat, but to absolutely all fixation points of the rafter system. | |
| For each node, at least two fixation methods must be used simultaneously. | In addition to nicks, use metal brackets or corners; supplement untrustworthy nicks with special stop boards, etc. | |
| Use templates only if you are absolutely sure that all dimensions and distances around the entire perimeter of the building are as identical as possible. | If you are not so sure, adjust each rafter leg separately. |
And we have dealt with this topic, now we can consider the most common methods of attaching rafter legs to the Mauerlat. We will talk about three: sawing with a stop (hard), sliding and layered methods.
Rigid fastening of rafters
The most reliable, most labor-intensive and most versatile method can be done by cutting or by sewing support bars onto the rafters. First, let's consider the option of cutting the rafters.
Don't worry if, as a result of cutting out your leg, the slope of the slope changes slightly. The main thing is that all the rafters lie on the same line. Before cutting the rafter leg, you need to take the dimensions of where it fits onto the Mauerlat, and this is quite difficult. We will not perform various mathematical calculations, it is long and useless, and in practice no one bothers themselves with such things.
Step 1. We offer two options: make one universal template for all legs at once or make cuts for each separately.
If everything is fine with the position of the Mauerlat, then it is better to make a template; if there are problems, then you will have to prepare each rafter separately.
The template can be made from a scrap board, a piece of fiberboard or thick cardboard. Draw a line on it at the bottom edge at a distance of no more than 1/3 of the width of the rafter leg. Draw the same parallel line on all rafter legs, mark where the rafters meet the Mauerlat, and draw a line perpendicular to it.
Now you need to trace the angle of the vertical and horizontal planes of the notch for one fit to the Mauerlat over the entire surface. Let’s say right away that it will not be possible to achieve the ideal option, but a loose fit of the planes of a few millimeters does not play a critical role. Attach the template to the end of the Mauerlat beam at an angle of inclination of the slope. The intersection point of the vertical and horizontal lines should be exactly opposite its corner. Draw the resulting triangle, cut out the drawn part.
Step 2. Check the correctness of the template in several parts of the mauerlat, walk along both sides of the building. If necessary, slightly change the angle of the sawn part; you need to achieve the most accurate fit of the notch around the entire perimeter.
Step 3. Attach the template to the rafters; the corner point of the upper stop should be on all rafters at the same distance from their ridge part.
Step 4. Using an electric saw or a hand saw, cut off the section across the grain of the rafter.
Saw very carefully, do not reduce the width of the remaining untouched rafters with the cut. If you have insufficient experience working with power tools, it is better to use hand saws. It may take more time and effort, but the likelihood of marriage is significantly reduced. And if you take into account the time for rework, then the loss of labor productivity from hand tools will not be so great.
Step 5. At an angle, select the second cut.
Warning: this is the most difficult job. It is not advisable to saw such a surface with an electric saw; there is a high risk of intercession. You need to work with an axe, the ax must be very sharp. Working with an ax will require not only skill, but also physical strength. By the way, the ability to work with an ax (not at the professional level) will always be useful when building a wooden bathhouse.
Step 6. Check the made seat with a template and correct it if necessary. You can prepare seats for the entire set of rafter legs at once, or you can perform the work one by one. It all depends on your skill and accuracy of installing the Mauerlat.
Step 7 Place the rafter leg in place and secure its position. For fixation, you can use homemade staples, metal corners or other durable devices.
Thus, you need to place the two outer rafters, pull the rope at the bottom between them and place the next ones in turn. Be prepared that for some rafters you will have to adjust the heel sizes several times. The more practical experience you have, the less often you will have to remove/install the rafter leg for adjustment. During installation of the rafter system, each pair of legs should be temporarily fixed with various wooden braces or struts. The temporary fastening is removed only after the sheathing has been inserted under the final roof covering.
Prices for edged boards
edged boards
Fastening the rafter legs with a stripe of a thrust block
For small baths, we recommend using this method - it is much easier and faster. As for the mechanical stability of the structure, it depends on the conscientiousness of all work. This method of fastening rafters can be used even by very inexperienced builders; it makes it possible to move the rafter legs in any position until they reach the correct position and fix the knot in place.
Step 1. Place the gable rafters in place and temporarily secure their position.
Step 2. Cut a piece of at least 40 cm long from a wide board. Determine the angle of inclination of the end facing the Mauerlat. There is no need to make an upper horizontal notch on the board; it does not carry any load. The vertical load will be supported by the rafters. In order to increase the area of their support in the Mauerlat, you should cut the seats in them to the width of the rafters.
There were no pieces of strong boards - nail two thin ones on both sides of the rafters. We only recommend mounting them on one through hardware (optimally long bolt); you should not weaken the rafters with a large number of nails or self-tapping screws.
Step 3. If you have boards on both sides of the rafters, then you may not need to use additional methods of securing the element from lateral tipping. If the board is on one side, you will need to secure them with metal corners or brackets.
It should be said that each rafter system on any building is carried out by craftsmen with individual differences. It all depends on their experience and preferences. And you may not strictly adhere to our recommendations; make original decisions on the spot, taking into account the characteristics of the bathhouse and the availability of building materials.
Work on fastening rafters should always be done using a rope; the ridge and lower legs should be controlled. If there are problems with height, then place wooden stops on the mauerlat; to prevent slipping, nail them with small nails or self-tapping screws.
Prices for a set of hardware
set of hardware
This method is used to build a rafter system in wooden log houses.
The fact is that the log house must stand under the roof, during which time it shrinks. Shrinkage, as a result, slightly changes the position of the rafter system; in the case of rigid fastening of the rafter legs, either deformation of the rafter system will certainly appear, or the stability of the top row of the frame will be disrupted. It is this row that plays the role of the Mauerlat. In order to increase the area of support of the rafters and the mauerlat, you need to remove the sharp edge of the latter. Otherwise, large loads will cause the beam to be pressed into the corner of the Mauerlat, and the rafter system will begin to change its position. This will be done unevenly around the perimeter of the log house - the rafters may significantly disturb their original position, and the roofing will become wavy. And this can break its tightness, resulting in leaks with all the very negative consequences.
Sliding rafters can be installed only if the rafter system has support in the upper part on the ridge beam and vertical stops; to enhance the stability of the structure, it is advisable to additionally install braces or headstocks. A specific decision should be made taking into account the size of the bathhouse, construction material and architectural characteristics of the roof.
Very important: if you intend to fix the rafter legs using a sliding method, then the fixation unit for the upper ridge parts should be made on a hinge. In the upper part, the rafter legs should oscillate in the axial direction, which gives them the opportunity, depending on the amount of shrinkage of the bathhouse, to change the angle of inclination of the rafter system. In this way, possible vertical loads are absorbed.
Step 1. Set the ridge beam according to the dimensions. It must be located exactly in the middle of the bathhouse, otherwise the angle of the slopes will be unequal. We have already described in the article above what difficulties the unequal angle of inclination of the slopes causes during the construction of eaves overhangs.
Step 2. Begin installation by installing the outer gable rafters.
For sliding fastening you need to buy special clamps; they need to be installed on both sides of each rafter.
Sliding support for rafters - dimensions
Step 3. Take the length dimensions of the rafters and determine the specific locations for their installation.
Step 4. To increase the plane of contact between the rafter leg and the Mauerlat, remove the angle of the beam. You can remove the angle along the entire perimeter (difficult and time-consuming) or only in the places where the rafter legs rest. To do this, make two cuts in the mauerlat at a distance slightly greater than the width of the rafter board.
Using a chisel, carefully remove the wood from the cut and level its surface. We advise you not to neglect this advice; such a simple installation method will make it possible to significantly increase the stability of the entire rafter system. In addition, there is no need to use other methods to ensure the system’s resistance to longitudinal wind loads.
Step 5. Carefully place the rafters on the prepared seats and secure them with floating metal mechanisms. They must be installed in such a position that most of the protruding unit allows the rafters to fall down; it is in this direction that shrinkage occurs.
Step 6. Stretch ropes between the outer gable rafters on the slope of the eaves, and mount all remaining rafters along the rope. If necessary, adjust the length of the structures. At the same time as the legs, fix the ridge parts of the rafter legs with a hinge joint.
This type of rafter system is considered the least stable. Despite the fact that the forces pushing apart the rafter legs are much less than the forces acting on bending, the sliding legs are the weakest unit of the entire structure.
Practical advice. If you have the slightest doubt about the stability of the constructed rafter system, strengthen it. It doesn’t matter exactly how the system is strengthened, the main thing is that it always has a fairly large margin of strength and reliability. Remember that strengthening the structure after a problem has been discovered is much more difficult than completing all the work in a timely manner.
There is another type of sliding method, it is more reliable in strength, but is only suitable for baths made of rounded bursa or round whips - the sliding method with a cut along an arc.
It is a little more difficult to make; each rafter at the point of contact with the upper rim of the frame must be cut in an arc. For cutting, it is better to use an electric jigsaw. The depth of the cut is no more than 1/3 of the width of the rafters. The mark can be removed from the end of the beam, the rafters can all be made the same. Such a connection has an additional degree of freedom, but at the same time eliminates axial movements - the reliability of the entire rafter system increases.
Diagram - rafters with sliding support and cuts
Prices for sliding support
sliding support
It is used when carrying out repair work on roofs of complex structures or when the available lumber is insufficient for the manufacture of rafters. Of course, the rafters can be connected and in this way increase the length. But builders do not advise doing these things; if you have the slightest opportunity to avoid connecting rafter legs, you need to use them. In addition to the fact that each connection requires a lot of time and labor, it always significantly reduces the strength of the rafters. We repeat once again - the load-bearing characteristics of connected rafters are always much less than whole ones.
It is better to use the layered method during the construction of the rafters, and use ordinary fillies to make the under-roof part of the cornice.
Step 1. Measure the exact length of each rafter until the end part stops in the mauerlat. Determine the angle of inclination of the thrust plane.
Layered rafters - diagrams
Make a gash along the marked line. If the width of the rafter leg allows, it is recommended to cut it with a tooth. The tooth will prevent the rafters from sliding along the mauerlat. If this is not possible, then at the bottom of each rafter leg you need to install thrust boards approximately 40 centimeters long. The boards are attached to the rafters with nails or self-tapping screws.
Step 2. To prevent lateral vibrations and general strengthening of the connection unit, the rafters are additionally fixed with metal corners or brackets. It is not recommended to drive large nails into the end due to the high risk of cracking the wood.
Step 3. Next you need to take care of the fillies for the cornices. Edged boards with a thickness of more than 30 millimeters are suitable for this. Cut them to length, taking into account the expected overhang of the cornice, and nail them firmly to the rafters. All work must be done only under a rope stretched between the outer gable rafters.
Prices for metal corners
metal corners
For the rafter system, choose only the highest quality materials; this is not a design on which you can save. Many ordinary architectural elements have several additional components of load-bearing structures; they complement and insure each other. The rafters work “alone”; in the event of instability, no other elements take on the load.
Try to make connections between the rafters and the Mauerlat in places where there are completely no natural defects in the development of wood, including healthy knots. The hardness of the knots themselves is high, but swirls of wood fibers form around them, and they are no longer distinguished by high levels of physical strength.
Make markings, and especially cutting, very carefully. To correct errors, you can use various pads, but this is highly undesirable.
And one last thing. You can find recommendations to install the rafter system yourself without help. Some of the simplest types of rafter systems can be done alone. The only question is, why is this necessary? Why risk your health if there is no time or money saved in the end. And the quality of the connection of all nodes will suffer significantly.
Video - Attaching rafters to the mauerlat, sliding support
Video - Installation of rafters
Video - Assembling rafters
Video - Quick installation of the rafter system
