The strength of a roof is the total strength and quality of all its constituent elements: rafters, beams, ridge girder and sheathing. And also how tightly and competently these elements are connected to each other. After all, almost every one of us is capable of understanding the cross-section and calculation of the roof load, but how can we secure the rafters so that the roof serves faithfully for at least half a century?
In fact, this is a whole science, and each type of roofing assembly has its own pros and cons, and the same type of fastening can have a very different effect on the strength of different roofs. Therefore, let's approach this issue with all responsibility!
Types of rafter systems according to the level of load on the nodes
There are two types of rafters - layered and hanging. Main design features:
Hanging rafters are distinguished by the fact that their upper ends always rest against each other and there is no support under their junction. And in order to balance the load from the roof, the lower part of their rafters is connected with another element - a tie.
The result is a regular triangle, in which only the lower element works to stretch. Another beam in the roof, where the rafters also need to be attached, is called a beam. It is located horizontally and supports the ridge girder.
Types of support units by level of rigidity
It is precisely those places where the rafters are attached to the roof elements that are called the support unit:
The support unit is not always static - sometimes it has to be made movable if some structural element is subject to unstable loads. It's like a car wheel that compresses, spins, squeezes and turns.
Something similar is realized in support nodes, only the degree of freedom in them can be different - from zero, when the node itself is already motionless, to triple, i.e. maximum:
- Support node with zero degree of freedom. Both ends in this case are rigidly fastened with corners on both sides. A rafter on a beam or mauerlat with such a knot cannot move at all.
- Hinge joint with one degree of freedom. In this case, the beam has the ability to rotate in a circle.
- Hinge joint with two degrees of freedom. Now, in addition to circular rotation, there is also the possibility of displacement. This provides special fastening of the rafters to the mauerlat or beams, and you only need to install the sliders or slides.
- Hinge joint with three degrees of freedom allows the beam to move both horizontally and vertically. True, circular rotation may or may not happen here.
Comparing fasteners
These metal corners are used for attaching rafters to the mauerlat, beams and walls:
Types of metal plates
Note that there are two types of such plates: nail and perforated.
Perforated ones have many holes for bolts and screws, and it is with their help that such plates are attached to wood. The advantage of perforated plates is that they are able to connect the necessary elements of the rafter system at almost any angle. Moreover, such plates can be easily cut to the required size. Install perforated plates on both sides of the connections.
Nail plates do not have nails themselves. This fastener is used only in factory conditions, or in the presence of a special press. The fact is that you cannot hammer such a plate into the rafters with a hammer - you need proper, uniform pressure.
Additional items
Sometimes, in addition to the same metal corners and nails, support bars are additionally used:
And also like this:
If you use flat or shaped steel fasteners in joint connections, then:
- The thickness of the wooden elements should not be less than 5 cm. All because of the screws.
- Secondly, simple nails cannot be used here - only screw or rough nails, which simply won’t come out. Especially if the wood for the rafters has a moisture content of more than 18%, i.e. not completely dried, and after this material dries, the nodal connections are always weakened.
- Thirdly, take nails with a diameter of at least 4 mm and a length of at least 40 mm.
- Always use two angle irons per assembly if possible. Just place them symmetrically.
Attaching rafters to floor beams
Floor beams sometimes act as a kind of alternative to tightening. Most often this happens during the construction of light attics - it’s more convenient. But you can only attach the rafters directly to the floor beams if you are confident in the reliability of the walls of the house. Because in this case there is no Mauerlat, and, as a result, the load on the walls is not distributed evenly - now it is point-loaded. And this is worse, of course.
By the way, it is not necessary to take thick beams for floors; a section of 5x15 cm is enough. Your main task is to make such a fastening so that the rafters do not begin to slide along the beam.
By the way, there is a big difference in how to attach the same rafters to the floor beams of single-pitched and gable roofs. So, the greater the load the roof experiences, the fastening should be done with a double tooth, while for single-pitched roofs one is enough. By the way, a double tooth usually has two spikes.
The most durable fastening is obtained if you make a notch, and with an additional tenon, which will also prevent lateral shifts of the rafters due to loads. On the other hand, it is important not to weaken the beam itself at the same time. Therefore, the cutout for the rafters should be made no closer than 25 cm from the edge (this will also help to avoid falcons), and only 1/3-1/4 deep from the thickness of the beam itself:
To ensure that the rafter leg does not slip off the mauerlat, a special notch is made in it. And in the Mauerlat itself, sometimes they make another one, a counter one - this is only more reliable, and the stubborn lock turns out to be strong.
True, the Mauerlat itself will be significantly weakened by this - take this into account. You can do this with it only when the Mauerlat is made of hard hardwood and has good strength.
The grooves alone will not hold the rafters in place, so be sure to additionally use metal fasteners. If your connection is stationary, it will be enough to drive nails at an angle, and for more unreliable structures, use clamp connections and metal plates. Forged wire, which is mounted into the wall for these purposes, will also help.
Another type of fastening of rafter legs to beams is bolted:
- Step 1. At the end of the beam that protrudes, make a triangular cutout. The hypotenuse of the cutout should be at the same angle as the angle of the rafters.
- Step 2. We also saw the lower part of the rafter leg at the same angle.
- Step 3. We place the rafter on the beam with a cut and fix it with nails.
- Step 4. Perpendicular to the rafter leg, we drill a hole for the bolt - through, so that the bolt can be entered from below through the cutout in the beam.
- Step 5. We put a washer on the bolt and tightly fix the entire assembly with a nut.
Upon completion of fastening, be sure to check the strength of all connections.
Attaching rafters to the wall
But not all rafter structures use a Mauerlat. Then how to attach the rafters to the wall itself? It's simple: we find a replacement for the Mauerlat and work with it.
For example, in frame construction, the frame beams act as a mauerlat, onto which the cladding is made:
If for some reason you have to attach the rafters directly to the wall, without a Mauerlat, then you definitely need to make a tightening - a board or beam that will connect the rafters into one and take on part of the tension.
Such fastening is not always possible at all. For example, foam and gas blocks are bad not only because they easily transfer their moisture to wooden beams. They don't hold fastenings at all. You can easily pull out the same nail, driven 10 cm into a block, with your hands - then how to secure the rafters? Plus considerable pressure from the roof rafter system on such fragile walls. Therefore, there is no way to do without a Mauerlat.
We attach the rafters to the mauerlat
In any roof truss structure, the rafters are placed with the lower end on the mauerlat, and the upper ends are connected at the roof ridge. Mauerlat is a special beam that is laid along the perimeter of the external walls. It is designed to support load-bearing rafters.
Now let's figure out when the rafters rest on the mauerlat, and when - only on the walls:
- If the walls are made of concrete, brick or foam block (in principle, any materials that are capable of transmitting moisture), then the rafter legs cannot be rested on them. Otherwise, the entire roof will quickly begin to rot. That’s why we use timber, called Mauerlat, and separate it from the wall itself with any roll waterproofing.
- In log and cobblestone houses, a Mauerlat is no longer needed for the rafters - it is enough to make notches in the top beam and use additional fastening in the form of metal corners and brackets.
And depending on whether the house shrinks, they make a rigid and sliding fastening of the rafters to the mauerlat.
Method #1 - rigid mount
To provide a rigid, immovable fastening to the unit, you have two options. The first is to use special corners with hemming bars and special cuts on the rafter leg. The rafter here is fixed with corners on both sides, and therefore can no longer move:
In the second method, which is more common, you need to hammer the nails at an angle to each other. In the Mauerlat they are crossed, and the third nail is driven vertically:
Two nails on the sides keep the rafter leg from moving left and right, and the top nail already pulls the rafter to the mauerlat itself.
Or use long screws instead of nails:
Method #2 - fastening with one degree of freedom
But in this design, a certain movement of the rafters under the pressure of the entire roof is already allowed:
But let us immediately note that if we are talking about the ability to move horizontally, we are not at all talking about the fact that the rafter will literally “ride” along the beam. This is just a small opportunity to move by millimeters due to dynamic loads and temperature and humidity changes. Moreover, the slider will move only under maximum permissible loads, and you will not be able to see such changes with the ordinary eye.
The possibility of some movement remains even when fastening the knot with nails - if there are not many of them. But those hammered in a checkerboard pattern with a certain force will no longer allow the rafters to move.
Finally, to secure the rigid fastening of the rafters to the mauerlat, additionally use wire or anchors. You just need to think about this in advance:
Or here's another great visual example:
Method #3 - sliding mount
A sliding mount is a mount that has two degrees of freedom. That is, in simple terms, one of the two elements has the possibility of displacement:
And this makes sense. Thus, those rafters that rest against the mauerlat with a notch, and against each other from above, evenly transfer the load from the roof and the snow on it to the walls. But those rafters that are supported by horizontal notches on the mauerlat and on the ridge girder are called a non-thrust structure.
As we have already said, a sliding mount, even with three degrees of freedom, does not actually mean that the rafter will move loosely back and forth on the support. All this is only for invisible physical laws.
It is usually used only under severe dynamic loads on the roof.
Method #5 – splicing with fillies
To install roof overhangs, you also need to make fillies from boards, 50x100 mm in cross-section and such a length that it is equal to the overhang plus another 0.5 m for the junction with the rafters.
Then everything is simple: nail the fillies to the rafter legs and extend them beyond the roof. Are you wondering why this rafter element is called that? They just used to be cut in the shape of a horse - for beauty. And often today too.
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 of 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 are the 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 adjusted 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 movable 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, the 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 cross 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 areas of 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:
And finally, we suggest you watch the video:
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!
- 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 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. It is impractical to build a roof with hanging rafters without crossbars. 
Technologies for attaching the rafter leg to the mauerlat
The connection of the rafters to the mauerlat is made both with the help of cutting, tapping, and sawing, usually occupying 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 fastening of elements is carried out 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 main rafter element is where the rafters are attached. The service life of the future roof and each of its elements depends on the correctness and reliability of this connection. It is worth noting that the future of the house depends on the quality of the roof construction. If something goes wrong, the house may collapse, in which case its inhabitants will not be in safe conditions every day.
We propose to consider the important stages of designing a roofing system. In this article you will find everything about the technology of fastening the load-bearing elements of the roof; we will also consider the reliable fastening of rafters to the Mauerlat.
How to attach rafters to the mauerlat
When performing such work, it is necessary to take into account the following nuances:
- The connecting parts of the rafters and the Mauerlat must be fastened firmly and securely;
- In the places where the rafters adjoin the mauerlat, it is necessary to make precise cuts that will ensure a good, tight fit of the structures;
- When performing such work, it is necessary to purchase plates, metal corners, special brackets, bolts, and threaded rods. Typically, such parts for rafters, braces, braces, etc. are sold in any hardware store.
- Plywood scraps are perfect as overlays; they can replace metal plates;
- If the house is wooden, then sliding fastening of the rafters is suitable, since a house of this type shrinks in the first two years. This type of fastening is especially suitable for houses with a soft type of roof. Such rafters are attached to the mauerlat beam or to the upper side logs.
- Before attaching the rafters, the lower part, where the rafter will be adjacent to the Mauerlat, must be sawed down. That is, in this case the saddle is in the rafters. It subsequently ensures a tight fit to the Mauerlat. The support of the rafters on the mauerlat must be strong. In this case, a pre-prepared template will help. It is on this that the cuts are made. Such cuts are made at an identical angle of inclination of the roof on each rafter.
If the angles on the slopes are different, then the cut for each slope will also be different. In this case, it should be no deeper than ¼ of the rafter width.
- The attachment of the rafter leg to the Mauerlat must be strong and reliable, that is, in the future it must withstand all the loads of the roofing system, the amount of precipitation and possible gusty winds.
Fastening the floor beams to the Mauerlat is done using steel angles. In this case, the design will be reliable. to the Mauerlat on a vertical “chair” is carried out according to the same principle.
The support of the rafter leg on the mauerlat must be correct and strong. The reliability of the roofing system and its service life depend on this.
It is worth noting that there are various ways to attach rafters to the Mauerlat. For example, they can be attached to each other using a skate. In this case, the fastening occurs end-to-end, or steel plates are used for connection.
It is worth noting that the structural elements require precise sawing; they must fit tightly to each other. Such points must be especially taken into account if the rafters are in a diagonal position. When fastening them, it is necessary to use bolts, plates, and angles.
How to attach rafters to the Mauerlat
Some believe that the rafters need to be fastened with twists to foam blocks or gas blocks. It is worth noting that this is a misconception. The fact is that stone blocks are not always able to withstand all fastening parts.
The twists will not be able to properly hold the mauerlat, rafters and other structures, since pressure will be constantly exerted on them. Take, for example, a 10 cm nail driven into a wall. If you apply a certain force, you can even remove it with your hands. What can we say about twisting, which will be under pressure from all sides.
Professionals advise attaching rafters to brick and other types of stone walls using a reinforced belt. In this case, its width and height should be 20 centimeters. Typically, threaded rods are attached to it before it is poured. In this case, the diameter should be from 14 millimeters, and the pitch should be 1 – 1.5 meters. If you choose small diameter studs, they will not be reliable due to their ability to bend.
The best option would be to use studs, to the base of which reinforcing crosses are welded. In this case, a reinforced washer with nut can also be used. The fastening of the rafters will be as reliable as possible.
When pouring a reinforced belt, professionals advise adjusting the vertical position of the studs using a level. This way, the pins on the Mauerlat will be easier to put on.
There are cases when the studs were inserted into the Mauerlat at an angle, that is, incorrectly. In this case, you need to try to drill them and then install them correctly.
How to attach the rafters to the mauerlat
Today, there are several types of rafter fastenings to the Mauerlat. They all have their own characteristics. Let's look at the most common of them. The photo shows various mounts.
- Brackets for beams type WB. Such brackets are designed for fastening the consoles of load-bearing beams. In this case, they usually work on the construction of wooden floors at home, but they also use.
Brackets have a lot of advantages. Firstly, they do not need to be inserted into a load-bearing type of beam. Thus, they are not able to weaken the load-bearing capacity of the structure.
Secondly, when working with brackets, no professional equipment or tools are required. They are fastened with simple nails, screws, and anchor bolts.
Typically, brackets are made of galvanized steel sheet, the thickness of which is 2 millimeters;
- Fastening of beams of separate type WBD. In this case, the beams may be of non-standard size.
This type of fastening of rafters to the Mauerlat also has many advantages. Firstly, there is no need to embed it into the supporting beam, that is, as in the previous case. The main advantage is that this bracket can be used for beams of non-standard sizes. Thirdly, such fasteners also do not require any expensive professional equipment or tools. Fastening occurs using the same anchor bolts, nails, screws;
- The universal connector is also in demand in such works;
- Beam connector;
- Fasteners for rafters LK. This element is perfect for the truss-sub-rafter system of wooden buildings. The advantages in this case are the same as those of the first option;
- Perforated mounting tape TM. This tape is necessary to enhance the load-bearing capacity of the structure. It can also be used to attach and adjust auxiliary roofing elements.
Using mounting perforated tape, you can securely connect parts and important elements. This tape, like the brackets, does not need to be inserted into the load-bearing beams. The structure is also secured using ordinary nails and screws;
- Reinforced corner of the Kyrgyz Republic. This type of fastening is intended for load-bearing elements of the rafter-rafter system of a wooden house. Using this corner, the rafters are strengthened on the mauerlat, ensuring the reliability of the supporting structure.
- Corner KR11 and 21. They are improved types of corners. Typically, such corners are used by professional builders. The risk of bolt breakage in case of shrinkage of the building or load of the rafter system is practically zero;
- Corner KP5. This part is perfect for fastening complex, large load-bearing structures;
- Corner KR 6. This corner is made of 3 mm steel. The part has an oval hole that helps securely fasten the anchor bolt. Thus, nothing will happen to it during the shrinkage of the house, the weight of the roofing system;
This corner is also widely used by professionals. It is designed for structures with large mass;
Fastening the rafters on the attic roof, see the video:
Such a corner does not need to be cut into the structure, it does not require the use of special equipment and tools, only screws and nails are needed;
- Corner reinforced KMRP. This type of corner is perfect for connections that have an angle of 90 degrees. In addition, it can be adjusted. This design has a stamping that can transfer very large loads to the corner. Installing rafters on the mauerlat using this corner will make the structure strong and reliable. This part has a unique hole, that is, the corner can be used even if the support is displaced.
- Mortgage support;
- Drive-in fasteners for racks;
- Perforated mounting tape TM. This type of tape can enhance the load-bearing capacity of a structural unit. It is suitable for attaching auxiliary elements, as well as their fixation.
With the help of such a tape, all elements are well, firmly connected, and fit perfectly together. In this case, there is also no need to insert the tape into the supporting structure of the beam. Not only professional builders use perforated mounting tape, since its use does not require special tools or equipment. Nails and screws are suitable for fastening it;
- Self-tapping screws;
- Rough galvanized nails with conical head.
In any case, installing a roofing system is one of the most serious and labor-intensive processes in building a house. Therefore, it is better to entrust such work to real experts in their field.
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