Mauerlat for the roof: its dimensions and fastening. What is a Mauerlat in the construction of a Mauerlat roof on two or four sides of a house
Or any other) of a modern private house begins with a Mauerlat. Mauerlat for the roof - this is the basis, a beam, which is fixed along the perimeter of the top of the outer walls. It serves to evenly distribute temporary and permanent loads from the roofing system to the walls and ensures the rigidity of the roof, "tying" it to the load-bearing walls.
Some builders prefer to lay the Mauerlat directly under the rafters, or do without it, but both options are not correct, since the strength and rigidity of the roof structure is lost. later in our article, we will try to tell you what a Mauerlat is for a roof and consider how does the Mauerlat fasten to the wall building.
1. Mauerlat device: its dimensions and material
Figure 1. Maurlat device options
used mauerlat for the roof not only for gable roofs, it is also used for single-slope and flat versions. Depending on the design of the roof, for its Mauerlat devices and fastenings use a bar with a dimensional section of 100 × 100 mm.
There is an unspoken rule - the cross section of the beam is equal to 1/3 of the thickness of the wall on which it will rest.
The timber should have a moisture content of no more than 20%, preferably with pre-impregnation with an antiseptic in order to remove the likelihood of insects in the wood. The Mauerlat is laid only on those walls on which the truss system will be supported, that is: if the roof structure provides only a standard gable version with gables, then the Mauerlat is mounted only on the longitudinal walls, perpendicular to the gables, if the type of roof is four-slope - around the entire perimeter.
Figure 2. Docking options (connections) docking maurlat beams
In the case of a difference in the size of the Mauerlat and the wall, the Mauerlat is arranged in such a way that its pieces are joined with the maximum length of each part. That is, with a standard size of lumber - 6m, and a wall length of 7m, use 2 beams 3.5m long, but not 6m and 1m. Mauerlat bar connections produce washed down on half the section of the beam. The junction of the Mauerlat is nailed with nails 150 mm long in an amount of at least 6 pieces, and fixed in the masonry.
When joining the beams in the corners, the same washed down is made with staples from reinforcement with a diameter of at least 10 mm driven into both beams.
It is necessary to hammer in the bracket so that it is the hypotenuse of an isosceles right triangle.
The Mauerlat is located closer to the inner edge (indentation - at least 5 cm from the edge), or along the central axis of the wall. This is done for further ease of installation of the roofing system and reliable fixation of the beam itself in the thickness of the masonry.
2. Methods for attaching the Mauerlat to the wall: basic mounting options
Figure 3. Methods for attaching the Mauerlat to the wall
Before installing the Mauerlat, it is necessary to arrange waterproofing for it. Although there is a huge variety of mastics, an ordinary sheet roofing material is suitable for this, which can be laid directly on the mounting surface, as well as wrap the Mauerlat itself with it, securing the material with a stapler.
Figure 4. Mauerlat for the roof: waterproofing layer device
Fastening the mauerlat beam to the wall can be completely different, the only requirement is the rigidity of the fasteners. This can be tying with wire laid during laying in the wall, or fixing the beam with a bracket nailed to the bars left in advance in the masonry, it can also be drilled into holes in the beam and wall into which reinforcement is hammered with further bending.
But the most reliable two options fastening mauerlat to the wall :
- the first is to drill holes in the beam and masonry, hammer the anchor studs into the hole and fix it with a nut and washer (without an armored belt device);
- the second is the installation of the Mauerlat on the anchors left in advance in the masonry (using the armored belt).
Both options are time-consuming in their own way, but the probability of "sliding" of the beam is almost zero. The step of fastening the Mauerlat to the wall is at least 1m. Hole depth - not less than 200 mm in the thickness of the masonry. The diameter of the hammered anchor should be from 10mm.
Mauerlat for the roof is a foundation on which a huge number of loads act: wind, snow, the load of the roofing system itself from the influence of these factors. But all this is compensated by a securely and firmly installed Mauerlat. Do not neglect the basic above rules when installing it and comfort in your home will be provided for many years.
The roof of the house consists of several elements, one of which is Mauerlat. What is Mauerlat in roof construction? This is a belt laid on the walls of the house around the entire perimeter. The rafter system of the roof rests on it. This means that the loads to which this roof element will be subjected are enormous: the weight of rafters, battens, roofing material and precipitation. That is, the question of why a Mauerlat is needed can be answered as follows - in order to evenly distribute the loads from the roof onto the walls of the building, plus firmly tie the rafter legs to the building.
What is Mauerlat made of?
There are several ready-made materials in the form of wooden or steel profiles: timber, steel angle, channel, pipe, I-beam. You can assemble a structure from boards by connecting them together. Consider each option separately, determine the advantages and disadvantages of each.
wooden beam
Bars of different sections are used depending on the weight of the roof itself. The minimum section of the Mauerlat is 100x100 mm, the maximum is 200x200 mm. Particular attention should be paid to the type of wood used. The fewer knots, the better, this defect does not work well in tension, forming rather deep cracks. The latter reduce the strength of the material. But it is the Mauerlat, like no other element of the building, that is subjected to tensile loads.
Mauerlat from a wooden beam for the roof of a house
Boards fastened together
If the roof is small, the load from it will also be small. It is recommended to save money by installing interconnected boards with a thickness of 50 mm instead of timber. Two boards 100 mm wide will create a beam with a section of 100x100 mm. Four boards 200 mm wide - Mauerlat with a section of 200x200 mm. You can connect with nails, screws, bolts (studs).
Mauerlat from fastened boards to each other
steel profile
Mauerlat metal is rarely used. It is expensive, any metal profile is an additional load on the walls, which is not welcome. A pipe is often used, but it acts as an addition to increasing the rigidity of the entire roofing system.
The pipe is passed through the rafter legs, in which through holes are made. The pipe itself must be attached to a wooden beam.
Mauerlat reinforced with steel pipe
Requirements for this system:
- the diameter of the pipe must be 100 mm less than the width of the rafters;
- holes in the rafter legs are made strictly along one axis;
- the pipe is fastened to the Mauerlat with clamps.
Methods for attaching the Mauerlat to the wall
There are several ways to attach a roof plate to a wall. This takes into account the presence or absence of a reinforced seismic belt - a strip foundation, poured as the upper trim of the outer walls and the entire structure of the building to impart solidity.
Mounting on armored belt
It all starts with the laying of a reinforcing frame made of steel reinforcement. In fact, this is a cage with certain cell sizes of two or three lattices connected to each other by a knitting wire. The frame is laid over the wall inside the installed formwork.
Stage 1. The process of installing the reinforcing frame
Anchors are welded or tied to it (thread, on one side, the other end is bent at 90 °). The length of the anchor is chosen in such a way that a threaded end protruding from the armored belt with a height equal to the thickness of the Mauerlat plus 5 cm. For example, the height of a wooden beam is 10 cm, then the fastener should protrude from the armored belt by 15 cm. concrete belt, its minimum location relative to the depth is half the thickness of the belt, then the total length of the anchor is 5 cm plus the thickness of the Mauerlat plus at least half the thickness of the armored belt.
Stage 2. Fastening anchors to the reinforcing frame
Attention! Anchors are placed relative to the length of the reinforced belt at a distance of 60-120 cm from each other on the same line strictly in the middle of the wall. More often, to determine the number of anchors, the ratio of the number of rafter legs is used. How many of the latter are in the roof structure, there should be a minimum of fasteners for the Mauerlat.
To fill the belt, M400 grade concrete is used: the proportional ratio of cement-sand-crushed stone is 1:3:3. The amount of mortar used is determined by the size of the foundation structure itself. The width of the belt should be equal to the width of the wall, height 150–250 mm.
Stage 3. Concrete pouring of the prepared reinforcing frame
Filling of the structure is carried out at a time. The formwork is stripped after 7–10 days, it is better to load it after 28 days, when the concrete has gained brand strength.
Preparation and installation of timber
The size between the anchors is known, it is transferred to the bars, in which through holes are made with a diameter slightly larger than the diameter of the metal fasteners. For example, if anchors with a diameter of 12 mm are used, the hole should be drilled with a diameter of 14 mm.
Important! Drill from bottom to top. That is, from which side of the beam drilling began, that side will be lower with a clamp to the armored belt.
Since one beam will not cover the entire wall with its length, then two adjacent beams must be joined by joining them to the floor washed down. The beam is sawn in half along the section to a length of 150-200 mm.
An example of a joining cut of a beam
Two elements are stacked on top of each other with sawn edges and fastened together with different fasteners:
- metal staples from reinforcement with a diameter of 12 mm;
- long screws;
- nails;
- self-tapping screws and fixing perforated profiles.
The Mauerlat assembly process is as follows.
It is important in the ongoing process - to set the Mauerlat horizontally. Therefore, it is checked by level. If it is necessary to raise some part of the structure, wooden linings are laid. It is necessary to lower, cut down the lower plane of the required thickness.
Fastening to a brick wall without armored belt
There are several mounting options here. Each of them has its pros and cons.
Wire fastening
You need a wire with a diameter of 4–6 mm, twisted in several layers. It is laid in brickwork, as a through element, at the level of 4–6 rows below the Mauerlat installation. After laying the Mauerlat on the wall, it is tied with wire from above, pulling it to the wall end.
It is important to correctly fit the twisted wires in length. You will have to take into account the height of the brickwork from the place where the wire fasteners are laid, the thickness and width of the Mauerlat, the length of the twist for tightening (about 15–25 cm). The resulting size is doubled, the width of the wall is added.
An example of fastening a Mauerlat beam with wire
The distance between the laid wires is determined in the same way as with anchors. The basic rule is to start installation after the masonry mortar has dried.
Instead of wire, steel pipes of small diameter can be laid in brickwork. And pass the fastening wire through them.
Use of wooden corks
Wooden plugs - the same beam of a smaller section, which is cut into small pieces 20–25 cm long. They are laid in brickwork, having previously been treated with an antiseptic composition. Here are a few options where you can install wooden plugs in the wall:
- in the top row in the middle of the width of the wall;
- from the inside of the wall under the Mauerlat;
- on the inside, under the Mauerlat, 1–2 bricks lower.
Usually, the Mauerlat is attached to the plugs with metal brackets.
Using pins and wire
It is necessary to prepare studs with a length slightly less than the width of the wall, plus 3 cm as a protrusion outside the wall structure. It is the protrusion that must be equipped with a thread, washer and nut. The opposite end of the fastener must be bent at 90°.
An example of the correct fastening of a Mauerlat beam with studs
The hairpin is laid in the brickwork in a horizontal position 4-6 rows below the installation level of the Mauerlat. The threaded end must come out from the inside. After mounting the Mauerlat, a wire is wound onto the stud, folded in several layers (3–4), which is pressed with a washer and nut. The free end is attached by any means and methods to the Mauerlat. There is an option when the Mauerlat is not fastened with wire, but the rafter legs are attached, which are pulled up to the Mauerlat, pressing it against the wall. The main task in both the first and second cases is to stretch the wire so that it assumes a strictly vertical position and, according to the degree of tension, is a string.
Anchoring
The technology is somewhat similar to the Mauerlat device using anchors along the armo-belt. The same anchors are used here, which are laid vertically in the brickwork to a depth of 45–50 cm. The lower end is bent at a right angle, it must be laid under the brick, and not in the seam between the bricks.
The main problem is to install the fasteners vertically. Therefore, advice - when assembling brickwork, constantly check the location of the anchor for verticality, using a plumb line or level. A slight deviation is a big problem when putting on a Mauerlat on fasteners.
Mounting the Mauerlat with anchors to a brick wall
Here, the preparation of wooden beams is also carried out, taking into account the distance between the mounting holes and their drilling.
Attention! All methods used according to the Mauerlat mounting technology without an armored belt are possible only if the differences in the upper ends of the walls are insignificant. If the difference is large (more than 1 cm), then you will have to pour a screed from a cement-sand mortar over the wall. The thickness of the screed is at least 5 cm.
Mauerlat assembly rules for a gable roof
Mauerlat for a gable roof - a belt laid out around the perimeter of the building. It does not matter here whether the rafter legs will rest on the entire supporting structure or not, because only two sides of the perimeter will be loaded. Mauerlat for this type of roof is a single device, monolithic in nature. Therefore, it is assembled in the form of a single structure using the above-described fastening technologies.
It should be noted that it does not always seem that it is possible to build a Mauerlat for a roof in the form of a monolithic structure. If the roof is cocked along the floor beams, then the latter are laid with their ends on the walls of the building, which means that the solidity of the Mauerlat is cut off precisely by the beams. What can be done in this case. Option one is to make half the beams washed down with their installation in the Mauerlat grooves, which are also cut out at half the height, taking into account the width of the beam. In this design, the height of the beams and the Mauerlat is chosen the same. Usually the latter is adjusted to the former. At the same time, the rafter legs try to rest against the beams, thereby reducing the load.
No need to think that the Mauerlat for a gable roof is some kind of excellent design from the Mauerlats of other roofing structures. It may differ from a shed roof, where often the high side rests against a facade wall erected above the back. In such a building, the Mauerlat is not used. Otherwise, it is an ordinary belt for even distribution of loads.
When choosing a power plate for a gable roof or other types of roofs, you need to understand that this is the foundation - the basis for the roofing system. It is she who is subjected to heavy loads, therefore, strict requirements must be imposed on the choice of material, the dimensions of the Mauerlat for the roof, on the installation technology, especially on the method of fastening. Therefore, answering in the article the question of what a Mauerlat is in roof construction and how to install it, all available fastening methods were analyzed.
Video installation instructions
Pitched roof designs are varied, but one of the components of the roof system is the Mauerlat. This part of the roof is important and performs several functions. For the proper arrangement of the roof, the type of Mauerlat, the technology of its installation and materials are selected.
What is Mauerlat and its functions
The roof structure includes many functional elements, as it provides protection for the load-bearing walls of the building. One of these components of the truss system is the mauerlat, which is a row or crown of timber laid on the top of the walls. Mauerlat is in contact with the upper area of the walls along the entire perimeter of the building, which ensures the performance of the functions assigned to this row of timber.
Mauerlat has a simple design
A simple Mauerlat device ensures its functionality and maximum efficiency. The beam system serves to evenly distribute the weight of the roof over all walls of the building, which is necessary to prevent skew and deformation of the roof. This is the first function of the Mauerlat, and the second is to hold and fix the roof on the walls.
The roof truss system is attached to the Mauerlat
What is mauerlat made of
The roof truss system is most often made of wood. Mauerlat is made from the same material. In wooden houses, the last crown of walls, which is securely fixed, can play the role of a Mauerlat. In buildings made of aerated concrete, brick and other similar materials, the Mauerlat is constructed using wooden beams with certain parameters depending on the dimensions of the walls.
High quality wood is optimal for the construction of Mauerlat
The Mauerlat is fastened to the walls using metal anchors. To do this, bolts are fixed in the brickwork, the length of which is greater than the thickness of the beams. Then, places for holes are marked on the boards, beams are laid, inserting the ends of the bolts into the holes. Special nuts are tightened from above, securely fixing the Mauerlat. Thus, to create the basis for the rafter system, wooden bars with a section of 150 or 200 mm are needed, anchor bolts are longer than the thickness of the bar.
Installation of the roof mauerlat
Mauerlat installation can be carried out with or without a reinforcing belt. The first option is optimal for insufficiently strong walls, which rarely happens. Therefore, installation without a reinforcing belt is most common.
Mauerlat is attached to the walls with anchors, but other fastenings are possible
Fixing to a brick wall
Before attaching the Mauerlat, a waterproofing material is laid on a brick wall, the edges of which, after installation, are fixed with brackets on the beams. And you can also process the edges of the walls with bitumen, and then lay the boards. This allows you to protect the base from decay and deformation. The next steps are as follows:
Fastening the base for the roof can be carried out with an armored belt. To do this, along the edge of the walls, a concrete pouring of the reinforcing structure is constructed from rods laid along the length of the walls and fastened into rectangular structures. Formwork for pouring consists of boards screwed from the outside and from the inside of the walls. Concrete is poured inside on the reinforcement and wait for a fixation time of 5 days or more.
The width of the armored belt should not exceed the thickness of the wall
Video: attaching the Mauerlat to the armored belt
Joining bars together
Mauerlat can consist of thick bars fastened together by a cut or washed down in half the thickness of the elements. If boards of 150x50 mm in size are used for the base, then they are laid three pieces in a row. Between themselves, the elements are carefully fixed with strong self-tapping screws, additionally installed on the anchor.
Video: splicing bars
Mauerlat internal thermal insulation
As a result of the construction of the base for the roof, small cold bridges are formed, which significantly affect the atmosphere inside the room. For example, the area of contact of the floor of the attic and the Mauerlat is often such a zone. In such situations, careful insulation is necessary.
For insulation, it is important to determine the zones through which cold enters.Before laying the insulation, all wooden elements must be treated with an antiseptic composition to prevent the development of fungus. Mineral wool is most often used as an insulating component, and expanded polystyrene plates, fiberglass materials, and polyurethane foam are also popular. The slabs of material are simply laid and glued on the surface of the required areas. An effective solution is sprayed insulation, namely polyurethane foam.
Features of waterproofing
Preventing moisture from entering the roof base structure is an important point in construction. Waterproofing protects the beam from decay and maintains the integrity of the truss system. For this purpose, the Mauerlat beam is wrapped with several layers of roofing material or one layer of waterproofing. Additional protection will be provided by pre-treatment of the boards with wood stain or other antiseptic and fire-fighting agents intended for wood.
Roofing felt and bitumen are a popular waterproofing option.
The minimum number of joints, high quality wood, the absence of cracks are important conditions for a long service life of the Mauerlat. In this case, waterproofing will protect the material well and make the structure durable.
Mauerlat for different types of roofs
The design of the roof base does not imply significant differences in the construction of different types of roofs. For simple gable roofs, the mauerlat is always placed on the walls, as it serves as a support and a layer for connecting the rafter system and load-bearing elements.
Depending on the type of roof connection, the type of Mauerlat fastening is determined
If it is planned to equip a residential attic in a house under construction, then the construction of the Mauerlat is carried out according to conventional technology. In this case, complex methods are not used, and the timber is attached to the walls with anchors. A special point is careful insulation, as well as waterproofing, since the attic should be comfortable.
Mauerlat for the mansard roof has a standard design
Hip roofs have a rather complex structure and therefore the Mauerlat system must be as strong as possible. The basis for the hip roof is created according to general principles, but the load on it is slightly greater than with a simple gable roof. To do this, it is best to attach the base to the armored belt.
The hip roof has four slopes
For the construction of a roof with two slopes, a Mauerlat is required that is securely attached to the walls. The main load is carried out on two walls, on which the roof slopes rest. In this case, fastening is suitable both with an armored belt and without it.
For a gable roof, the Mauerlat can be fixed by any method
Fastening rafters to Mauerlat
The rafter system must be firmly fixed on the Mauerlat. To do this, you can use two mounting options: a steel corner and nails. In the first case, the steel angle is nailed to the rafter with three or one nails on each side, depending on the required degree of mobility. The second method is more common and involves driving two nails at right angles to each other, and the third nail is attached vertically.
Each method has a certain degree of reliability
Video: attaching rafters to the Mauerlat
The Mauerlat system requires a careful device to ensure the reliability of the roof. Therefore, it is important to calculate the parameters of this component of the truss system and perform installation in accordance with the technology.
Mauerlat- this is a structural element of the structure of the roofing system.
Often a person who encounters this word for the first time pronounces it as maurlat or murlat.
How to pronounce the word correctly: Mauerlat- stress on the last syllable.
Mauerlat is a wooden beam or log laid on top along the perimeter of the outer wall of the building, that is, along the facade wall. It serves as the extreme lower support for the rafter legs. As a rule, it is made of coniferous wood, except for the construction of a metal roof frame, when a metal channel, profiled pipe or I-beam can be used.
The main purpose of the Mauerlat- this is tying the wooden roof structure to the walls of the house. Second, no less important, distribution of the weight load transmitted from the roof from the rafter legs to the upper parts of the load-bearing walls.
Mauerlat dimensions
The range of sizes can be from 100x100 mm on small arbors and awnings, up to 250x250 mm on complex attics. There are also larger sizes of Mauerlats.
As a rule, the main variable dimensions are 150x100 mm, 150x150 mm, 200x100 mm.
The first thing that always begins with the construction of a truss system is with the installation of a Mauerlat.
The main rule of installation: In places where the Mauerlat comes into contact with non-wooden elements, the Mauerlat is insulated with a waterproof material (roofing material), which prevents reaction with concrete, which causes wood decay.
Each link of the mauerlat is connected to two neighboring ones, which, coupled with fastening to the rafters, creates a reliable, stable structure around the entire perimeter of the roofing system. Mauerlat can also be placed under the rafter legs in separate segments.