Mauerlat for gable roof with own hands

Mauerlat is a special belt, laid along the perimeter of the upper end of the external bearing wall of the building and intended for fastening the rafter legs. Wood is considered a traditional material for the manufacture of this element of the rafter system, but if a metal frame is installed under the roof, then metal rolling - I-beams, channel bars or profiles - can also be laid as mauerlat.

Mauerlat for a gable roof with their own hands is relatively easy to install - there are several different technologies for this. But it should be remembered that the more reliable it is fixed to the wall, the longer the life of the entire structure of the rafter system will become.

Purpose mauerlat

Mauerlat serves to reliably connect the house box and the roof and roof structuresand. In addition, it is designed to evenly distribute the static loads around the entire perimeter from the weight of the roof, consisting of a massive rafter system and a roof pie .

Another challenge that this element of the rafter system is designed to do is to counteract the load from the roof sail, which can contribute to damage to the structure or even its failure during a strong wind. In a word, the roof is "tied" to the walls.

You can find roofs, rafters which are laid on the top of the walls or fixed to the beams of the ceiling without installing the Mauerlat. In this case, the load from the rafter's feet will be concentrated in the places of their support without distribution on the whole wall, which may eventually lead to damage to the wall structure.

Since Mauerlat is the link between structures made from materials of different characteristics, and heavy loads fall on it, you have to come up with a special responsibility for assembling it.

Materials for the manufacture of Mauerlat

Mauerlat can be made of wooden beams, boards, logs, as well as metal profiles - channel, pipe, I-beam.

• Most often, the Mauerlatt is made from a bar. Its size in the cross-section to a certain extent depends on the size, and hence the weight of the future roofing system, as well as the size of the rafter feet.

However, given that the Mauerlat should be firmly laid on the end of the wall, distributing the load, the concealing or bending stresses in it are small, and with the load on the compression the wood does well. Therefore, in most cases, the Mauerlat does not require a complex calculation of the cross-section, and we usually use beams with sides multiples of 50 starting from 100 × 100.

The table below shows the dimensions of the sawn sections most commonly used in the construction of roof structures in individual construction.

Table of sizes of wooden elements of the truss system:

Elements of the truss system	Section of the lumber, mm
Mauerlat	Bar 100 × 100, 100 × 150, 150 × 150, and sometimes more.
Riser's legs	Board or beam 60 × 150, 80 × 150, 100 × 200 - based on the results of the
calculations. Runs	Bar 100 × 100, 100 × 150, 100 × 200.
Tightenings( crossbars)	Board 50 × 100, 50 × 150.
Racks	Bar 100 × 100, 150 × 150.
Braces, foals, board cornice box	Board 50 × 100.
Wind end and hem boards	Board 20 × 100, 25 × 150.

The beams for the Mauerlat should be chosen carefully, paying attention to its evenness and integrity. Driven, deformed lumber is not worth purchasing, even for economy reasons, since it will be more difficult to install it on even walls without creating internal stresses. The wood should not have deep and wide cracks and knots.

Knots are dangerous not only because they differ from all wood by their density and the separation of tar from them, as many think, but also because they significantly weaken the bar. In addition, if a rafter is attached to the knot, it will be more difficult to screw in the fastening element or hammer the brace, and besides, they will not hold tight in such a structure of wood.

• Boards, fastened together, are used for lighter rafter systems that do not have a warm "pie", for example, when building a summer cottage. For such a version of the Mauerlat, for example, board thickness of 30 ÷ 50 mm, laid in one or two layers, will do.
• Mauerlat is made of metal elements rarely, but profiles are sometimes used for combined variants, which include both wood and metal.

When using this option, the load from the rafters is distributed not only to the wood, but also to a pipe laid over the timber through wooden liners and pulled by mauerlate clamps. When selecting pipes for strengthening the Mauerlat, it is necessary to adhere to certain criteria for their selection:

- because the pipes will be passed through through holes in the lower part of the rafters, they should not have too large diameter - 40 to 50 mm is enough.

- it is necessary to take only a new pipe, and before installation it must be covered with anti-corrosion paint.

The holes in the rafters for the passage of the pipe must be made, deviating from their lower cut approximately 100 ÷ 120 mm.

In the wooden mauerlate, cutouts are made, in the bottom of which the front side of the rafter leg will rest. Sometimes on the board of the Mauerlat, the holes for installing the rafters are formed by fixing pieces of timber with a height of 80 ÷ 100 mm at a certain distance from each other. The width between the installed lengths of bars should exceed the thickness of the rafters, approximately 8 ÷ 10 mm, so that it freely enters the prepared gap.

Due to the fact that the rafters will not be rigidly fixed to the Mauerlate, but mounted on sliding fasteners, the system will be able to small displacements when shrinking the structure.

This diagram shows a variant using a combined version of the Mauerlat consisting of a wooden beam and a pipe extending beyond the bearing walls along their length. This design feature allows you to immediately make the basis for a protective visor on the front of the roof.

Basic ways of installing the Mauerlat

wall. Having chosen the material for making the base for the rafters, you need to decide whether the reinforcement belt will be poured over the top of the wall. This element of the construction is reinforcing and is provided, as a rule, on block, brick or backfilling walls, giving the roof a reliable foundation. If the walls are monolithic, or the brickwork is made in several rows in thickness, then from the reinforcing belt they refuse to simplify the work, save money and facilitate the whole construction of the house.

Thus, there are two types of arrangement of the base under the Mauerlat - with the filling of the reinforcing belt and without it.

To ensure good ventilation of the attic space and to avoid rotting of the wooden elements of the structure, it is recommended to fix the Mauerlat 300-500 mm above the beams of the attic floor.

The mounting of the Mauerlate to the walls can be made in various ways, depending on the existing base:

• The Mauerlat bar is rigidly bound throughout the perimeter of the structure in a single frame. Since lumber usually has a standard length of 6 m, the mauerlat is assembled from several lengths of timber. They are joined together by an oblique prirub or half-tree, and the junction is additionally fastened with screws, screws or wooden nadges.

The corner units of the frame are fastened with metal plates or staples. The frame can be additionally fixed by brackets and to the wall. One side of this element is driven into the Mauerlatt, and the other to the wall. In the presented scheme of fixing the Mauerlat, this option of fixation is shown on the left side.

The connection to the half-tree can be done with a stud welded into the wall in advance, or with anchor bolts driven into the through holes of the joint parts of the bar.

This kind of fixation of the Mauerlatt to the walls is possible without a reinforcing belt.

• The right side of the above diagram shows the installation of a bar on a reinforced concrete belt, into which studs are fixed for a fixed distance to fix the Mauerlate on them.

. This method of installation is used for light filling walls or for erected from foam concrete and gas silicate blocks. In such a construction, the main load from the rafter system falls on the reinforcing belt, and the mauerlat evenly distributes it along the entire perimeter.

Let's consider both cases - with reinforcing belt and without it, in more detail

Installation of Mauerlate on the wall without reinforcing belt

Basic installation and fastening options

There are four variants of installing Mauerlat on a brick wall without reinforcingbelt The simplest and therefore the most common, when the cantilever is fixed from above the walls to the waterproofing material:

- The entire thickness of the wall surface, when the walls have tIn one brick.

- At the level of the inner surface of the wall, in which a wooden plug with a depth of ¼ of brick is embedded below the upper end. In this case, the staple is driven into the mauerlat and the cork.

- At the level of the inner surface of the wall, on the upper edge of which, before the Mauerlate, a smaller wooden block-cork in the cross section, treated with a bitumen primer, is fastened from its outer side.

- At the level of the inner surface of the wall, over the previously fixed on it board-cork, which has a brick height.

The installation of wooden mauerlates on the wall is thought out in advance, taking into account the preparatory stage, which is carried out even during the masonry:

• The masonry rises above the joists on three or four brick rows. The surface of the wall must be level. Then another row of bricks is laid, but on the inner side of the wall, instead of a brick, a treated cork-plug is installed, having a thickness equal to the height of the brick.

Then another brick row is laid on top, overlapping the auxiliary wooden element.

Next, along the inner edge of the wall is laid waterproofing material, on top of which is laid a cantilever beam. On the remaining surface of the wall width, next to the Mauerlate, another brick row is laid, this will protect the wooden part from external moisture. From this horizontal side, the beam should also be separated from the brick by a layer of waterproofing

. Once the solution has completely cured in the brickwork, a bracket is fixed into the mauerlat and the auxiliary cork block fixing the wooden base on the wall.

• In the second case, the wall masonry is made entirely of bricks to the required height. When laying the next row, approximately in the middle of the thickness of the wall, wooden plugs, treated with bitumen, are mounted, and on the inside, a "shelf" for the Mauerlat is left. On the outside, next to the cork, is placed a brick. Further, a waterproofing spreads over the surface, and a Mauerlat is fixed on top of it, which is fixed with clamps to the plugs.
• In the third variant, all work is carried out in the same way as the second, but the masonry ends in two rows to the desired height. Then, at the level of the inner edge of the end of the wall, plugs impregnated with bitumen, having a width greater than the width of the Mauerlate, approximately 50-60 mm, and a height equal to the height of the brick, are embedded. Near them a row of bricks is placed on the width of the wall or with a ledge outward. At the top of the wooden cork, having retreated from its inner edge 10 ÷ 15 mm, the Mauerlat is laid, which is covered from the outside by one row of bricks.

Masonry is made with a shift of bricks outward to 30 ÷ 50 mm, thus forming a stepped ledge. Due to the fact that the outer brick row rises above the level of fastening of the Mauerlat, additional thermal insulation of the structure is provided, which is not observed in the simplest form of fastening, when the wooden beam is simply installed on the waterproofed upper wall end.

It is worth to focus on waterproofing. This material is laid in such a way that it separates the untreated wood from the brick or other masonry material. For waterproofing, not only a roofing material, but also a linocut, a technonikol or a hydroisol can be used.

Fasteners

Mauerlat can be permanently fixed to the wall in various ways - staples, wire, threaded studs or anchor bolts. How this is done - will be discussed below.

Wire twisting

If it is planned to fix the Mauerlate to wire twisted, it is laid along the inner edge of the wall, and the outside is brickwork.

For work you will need steel wire - "wire rod", having a diameter of 5 ÷ 6 mm. It is laid at the stage of erection of the wall for 4 ÷ 5 rows of masonry up to the top, usually doubling. The free length of the ends of the wire on both sides of the wall should be kept so that it is enough to twist on the inner edge of the installed mauerlat.

The twisting itself is carried out with the help of mounting or scrap.

Another option for securing the Mauerlat with twisting - the ends of the pre-embossed wire are passed through through holes drilled through the beam.

In this case, the wire from both sides is lifted to the edge of the wall, then it is bent and passed through the through holes of the Mauerlate from below, and then twisted so that the beam is firmly pressed against the upper surface of the wall. Fastening by means of twisting is made with a step equal to a step of installation of rafters - connecting knots appear between adjacent rafter legs.

Fastening with clamps

As already mentioned above, in some cases wooden fittings are embedded in the brickwork, which have a width and height equal to the size of the brick. Sometimes they practice a cork made of a bar, running along the entire wall parallel to the mauerlat.

The plugs must be carefully treated with a bitumen primer, in order to prevent the wood from absorbing atmospheric moisture. The insert of the wooden plugs has already been described above, and it remains only to consider fixing the Mauerlat to them with the help of staples.

In order for the clamp to go into the wood gently, without splitting it in two, it is recommended to drill holes equal to the ends of the staple in the markings by the markings. Then the bracket is installed in the intended holes and is hammered into them with a hammer.

Mounting the flywheel on the studs

Another option for fastening the Mauerlat is to attach it to metal threaded studs or to reinforcing bars, embedded in the masonry. This method of anchoring is used in the event that the walls of the building will have a high load. Hairpins are usually placed between the rafters at a distance equal to the step of setting the rafter feet. This distance can sometimes be increased, but in any case it should not exceed 1500 mm.

The fastening is carried out in the following order:

• The pieces of reinforcement are prepared, bent at the bottom in the form of the letter G, or studs with a diameter of 10 ÷ 14 mm, in the lower part of which a horizontalA piece having a length equal to the length of the brick. This form of hairpin is necessary for a more rigid installation of the element in the masonry.
• If a L-shaped variant of a stud or armature is chosen, it will be enough to deepen it into a masonry in three rows, that is, approximately 200 mm. If the flat hairpins are installed, they are recommended to be embeded to 350-400 mm.
• The next step on the upper row of masonry is laid waterproofing material. In order for the waterproofing to lie flat on the surface of the wall, in the places where the hairpins leave the surface, holes are cut in the web material.
• Further, a marking for holes is made on the bar of the Mauerlat, through which it will be put on the studs. This process can be done quite simply, even without a ruler and a pencil. For this, the bar is installed from above, onto the protruding studs, and it is taped from above with a hammer in the areas of the fasteners. On the bar there must remain dents, through which through holes will be drilled. The diameter of the holes must exceed the diameter of the hairpin by 2 ÷ 3 mm, so that the beam can easily be mounted on the fasteners, without any distortion.
• If the cantilever is mounted on studs with threads in the upper part, then they put on a wide washer and tighten the nut. If the Mauerlatt is mounted on the armature, its free end must be bent at right angles and fixed to the surface of the beam with powerful nails, which are clogged and then bent.

Anchorage fasteners

This type of mounting is suitable for the Mauerlat, which will have both a small and a high load. The main difference between the anchoring of the timber to the wall is that it does not require any pre-embedded elements.

Illustration	Brief description of the operation
	The first step for pouring the reinforcing belt is the formwork. It can be made of different materials. Most often, for the installation of this box, boards are used, and for their fastening - bars. This is the most affordable material, which after hardening of the belt can be removed and used again. It is possible to use third-grade sawn timber. To ensure that the grouted solution does not seep into the gaps between the boards and in the joints between them and the wall, it is necessary to fix a dense polyethylene from inside on the wooden walls, which can be removed after the concrete has hardened.
	Another formwork consists of two layers - a plywood having a thickness of at least 10 mm, fixed to the wall from the outside, and a heat insulation material installed from inside the structure and pressed against the sides of the plywood.
	It is desirable to install a heater on the waterproofing sealant, and also glue with its corner joints of the material, and then wait for it to dry. Then poured into the formwork solution, completely remains inside the formwork.
	Another option is a fixed formwork made of expanded polystyrene. It is a hollow block, which is assembled into a single structure, and it is also desirable to fix them on the wall with a waterproof sealant. This design is simultaneously a formwork and thermal insulation layer that will reduce the impact of a powerful cold bridge through the concrete belt, will keep heat in the attic. However, using foam blocks or an inner layer of thermal insulation on the formwork makes sense if the roofing system itself is completely insulated. From whatever material the formwork is built, its upper edge must be carefully aligned horizontally with the help of a level.
	The next step is to build a reinforcement structure. Along the inner walls of the formwork, along the upper and lower edges, with an indent from the top and bottom of 15 ÷ 20 mm, reinforcement is installed.
	The reinforcement is tied with a thinner wire, and the shape of the carcass should generally repeat the shape of the inner space of the formwork.
	The individual parts of the reinforcement are fastened together by wire twisting.
	In order to create the necessary clearance between the inner walls and the reinforcing system, and at the same time the structure was fixed in one position, special fasteners are installed on the armature bars.
	The asterisk is often used to create a gap between the formwork wall and the reinforcement, which must necessarily be filled with a layer of concrete. Clamps are produced under different numbers, which determine the thickness of the concrete layer that will divide the reinforcement and, in this case, the insulation, and in other cases the outer edge of the wall or formwork to be poured. That is, the reinforcement structure is completely hidden inside the concrete and will be there in complete safety against corrosion. The distance can be from 15 to 75 mm. Clamps are installed in steps of 500 ÷ 750 mm.
	After finishing the reinforcement of the formwork, at a distance equal to the step between the rafters, the studs are installed, since in this version they are placed in the reinforcing building of the belt. At the bottom, the hairpin must be L-shaped. This bend is installed on the bottom of the formwork, in the middle part of the reinforcement structure, and rigidly fixed with wire twists in two places - on the horizontal lower and upper jumper. Studs should stand strictly upright and on the same line, and rise above the future belt by the thickness of the Mauerlat, plus 50 ÷ 80 mm.
	The next step is to fill the formwork with concrete mortar, the surface of which is leveled on the walls of the box. Align the surface of the reinforced belt with a rule or a flat board.

An anchorage consists of two elements - the most spread anchor, installed in a hole drilled for it in the wall and beam, and the screw that is inserted into it, and on which the nut is screwed. When the nut is tightened, the screw moves upwards, together with the conical head, which spreads the "petals" and ensures a reliable fixation of the fastening element.

Installation work on the installation of Mauerlat in this way is carried out in the following order:

• The wall is covered with waterproofing material.
• On top of it is laid a cantilever beam.
• Next, a marking is made, through which through holes will be drilled.
• Anchors should have a diameter of 10 ÷ 15 mm, respectively drill holes drill bits of 12 ÷ 17 mm. The drill must pass through the bar and go deeper into the wall at least 180 ÷ 200 mm.
• The next step in the holes drive in the anchors with the screw part, which is then tightened with a nut nut, under which is placed a wide washer.

Fastening the Mauerlatt to the reinforcement belt

The reinforcement belt for the rafter system will never be superfluous, even if the walls of the structure are strong enough, since fastening the Mauerlat to it is as reliable and durable as possible. For some buildings reinforcing belt is simply necessary, for example, it concerns filling or built of aerocrete blocks of walls. Aerated concrete is fragile enough to hold fasteners very poorly.

Creation of reinforcing belt

Reinforcing belt for installation of Mauerlat can be done without helpers. Of course, if the work is carried out by one person, it will go much more slowly, but the main thing in this case is the opportunity to save money.

The reinforcing belt is a concrete belt, inside of which is a metal frame made of reinforcement. The width of the belt should correspond to the width of the wall, its height is 200 ÷ 250 mm, and it runs along the entire perimeter of the structure. It is very important to provide that the number of fasteners should be equal to the number of rafter legs. Therefore, calculating the number of rafters in the roof structure, the step of the location of the fixing embedded parts is calculated.

In order for the belt to be strong and not crumbled, M400 ÷ 500 cement is used to prepare the mortar, and the ready-made concrete is poured into the formwork in one run.

The solution for pouring reinforcing belt is made of cement, crushed stone and sand, in proportions of 1: 3: 3.Sometimes plasticizers are added to the mixture, which allow the solution to be dried to dry out evenly, reduce the amount of water used when it is kneaded.

Briefly, the casting belt is shown in the table below:

After the reinforcing belt has solidified( at least 15-18 days or more depending on its thickness), you can proceed with the installation of the Mauerlat. This process will not be any different from the analogous operation, when the studs were embedded in the brickwork.

Video: the original solution to the question of creating a reinforced belt under the Mauerlat on the aerated concrete wall

Other ways of installing the fasteners for the Mauerlat

In addition to the above, there are other ways to fasten the studs to reinforced belt concrete for installing the Mauerlat.

A. Formwork is installed according to the same principle - from boards, plywood or foam plastic non-removable blocks. In addition, the walls of the formwork can even be made of ordinary or aerated concrete bricks.

• The reinforcement structure is also installed inside the formwork, but the studs are mounted differently before pouring into the formwork of the mortar.
• The wooden walls of the formwork are fastened together by bridges, set at the same distance from each other - it must correspond to the step of fastening the rafters. On the slats the middle is determined, at the found point a hole is drilled with a diameter of 2 ÷ 2.5 mm larger than the diameter of the stud.
• Next, a pin is installed in the hole, having a height of 100-150 mm greater than the height of the belt and the Mauerlat. From the bottom on the pin is screwed into the nut - in the place of emphasis in the bottom of the formwork, that is, to the end of the wall of the house. In addition, it is desirable to fix the pin with two nuts on the jumper itself, in order to install it strictly vertically. The upper nut will then be easily removed during the removal of the formwork. In the same way, all the other studs are installed.
• When all the embedded elements are installed, a concrete mortar is poured into the formwork and leveled to the level of the walls.

If this way the studs will be installed in a formwork laid out of brick or aerated concrete, then the wooden pads with a hole for the stud can be simply installed without even attaching them to the walls.

Concrete mortar in the formwork should freeze and gain strength also for at least 15 days. Forming is only permitted after concrete has attained at least 70 ÷ 75% of brand strength.

B. Mauerlat can be anchored to the reinforcement belt in the same way as to walls built from other materials.

B. If it is decided to fix the wooden beam with a wire, then it is screwed to the fitting, prudently installed inside the formwork and protruding from both sides of the belt.

Waterproofing layer for Mauerlat

Waterproofing on the end of the wall or on a concrete belt is laid to preserve the bar of the Mauerlate from penetration into the wood of the capillary from the building structures and, accordingly, to prevent decomposition processes. Waterproofing is recommended to be laid on the entire width of the wall, and for better adherence of the material to the wall material, it is fixed to bitumen mastic, which in itself is a good waterproofing.

In the waterproofing material holes are cut if it is mounted on top of the studded studs. The material must be stretched, as there should not be wrinkles or gaps between it and the concrete belt.

With mastic it is necessary to work neatly so as not to spoil the external side of the walls, especially if it is not covered with finishing material.

A few words about fixing the rafters on the Mauerlat

As mentioned above, the purpose of the Mauerlatt is to distribute the load evenly from the truss system over the entire surface of the wall. And from the way it performs its function, it will depend on how the whole roof structure behaves when additional loads are applied to it in the form of wind or snow drifts.

There are two ways to fasten the rafters to the Mauerlat - hard and slippery, and which one to choose - first of all depends on which roofing system is chosen for the roof installation - nylon or hanging.

• Rigid fastening

Rigid fastening assumes complete elimination of any system parts offsets. It is most often used for gable roofing system rafters, which has additional support in the form of a capital partition inside the building.

For mounting a rigid structure, several types of fastening are used:

- Support beam and metal corners.

- Cutting of the rafter's foot into the Mauerlat and additional corner brackets. The cut in the rafters should not be more than ⅓ its width.

- Fixing of a rafter leg with the help of puffs and a metal corner.

- Cutting with a notch in the Mauerlate and staples driven into the rafters and mauerlat.

- Additionally, the notched moorlat on the rafters is often fastened with nails driven at an angle.

Here it should be noted that if a house is built from a log or a beam, the role of the Mauerlata is most often performed by the upper log, on which the truss legs are fixed.

• Sliding fastening

Sliding fastening is most often used in a gable hanging system where the rafters rest only on external load-bearing walls and do not have additional intermediate support. Sliding elements fixed on rafters and mauerlat allow the construction to shift when shrinking the house or when the external loads on it increase.

Especially this design is important for wooden log houses, since after construction, shrinkage is inevitable, sometimes reaching up to 15%, and, as a rule, it is uneven.

The deformation processes of the elements of the rafter system can also affect the period of its operation. So, in rainy time wood can swell from moisture, as it is hygroscopic enough, and in winter frosts and in extreme heat - shrink.

The sliding fastenings help to maintain the integrity of the structure, because when settling, its individual parts can move after the wall.

In addition to the sliding fastenings of the rafter legs on the Mauerlat, the hinge from the movable plates can also be installed as a ridge connection. This kind of fastening of the elements also helps the roof structure to remain intact when its geometry changes during periods of shrinkage or other fluctuations.

In order for the roof to be reliable in all situations, before starting the installation it is necessary to draw up its drawing and calculate all the parameters. If the process of erecting the truss system is performed for the first time, the best option is still to seek the help of specialists, since the strength of this design depends on many of the nuances that are simply unknown to the novice for inexperience.

In conclusion of the publication - another interesting video story - the home master shares the experience of installing the Mauerlat on a monolithic wall.

Video: installation of the Mauerlat with your own hands