Installation of rafter system and sheathing. How to install a gable roof rafter system - a step-by-step guide. Features of installation of different types of roofs
While building your house, you will definitely encounter many difficulties. First you need to draw up a project, then prepare the material, and then begin building the structure. Each stage has its own characteristics and difficulties; if you do not get acquainted with them in advance, then construction can easily be delayed. For example, installation rafter system. The durability of the entire house depends on the correct execution of this stage. How to do it correctly?
First, about the design itself
Installation of the rafter system is carried out in a certain sequence. To know how to do the work, you must first become familiar with the structure itself. The roof truss system consists of the following main elements:
- The lowest “tier” of the rafter system is the mauerlat. It is a wooden beam located around the entire perimeter of the building. Mauerlat serves two purposes. Firstly, it evenly distributes the load from the rafter system onto the walls of the house. Secondly, the Mauerlat allows you to level the base horizontally;
- Rafter pairs are the main element of the entire system. It is he who takes on all the loads and also connects other components;
- Run. Represents wooden beam. Most often it is installed up at the ridge and connects the rafters. Also, in some cases, the purlin is installed from below. In this case, it serves as an additional fastening element for the rafter legs;
- Puff. It is required to be used in. The tightening fastens the lower ends of each pair together. In some cases, the element may be located in the upper part of the rafter triangle;
- Struts, racks. The elements serve as additional support for the rafter legs;
- Filly. Additional element. Installation of the filly is necessary in order for the overhang.
- . Such rafter systems are used in cases where the house has a small width. The span length should not exceed six meters. Hanging system implies that the rafters rest only on the mauerlat or directly on the walls. From above, the pairs are simply connected to each other; there is no ridge run. From below, the rafters are additionally attached to each other, in pairs, by guy wires;
- . This rafter system is used if there is a passage in the middle of the house. bearing wall or column. They serve as a support for installing the ridge girder. The layered rafter system is used in the construction of wide houses.
The rafter system has both mandatory and optional components. For example, Mauerlat. It is used almost always, with the exception of houses from wooden beam. Here you can do without an element. In this case, the role of the Mauerlat will be played by the upper beam.
Some experts also include sheathing in the rafter system. This structure serves as a support for the roofing material. In some cases, a continuous sheathing is required, and in others, a thin sheathing is required. The first option is used for soft roofing. 
Types of system
Rafters are the basis of the entire roof structure. They are the ones who take on all the loads and transfer them to the walls. If we are talking about a gable roof, and this is the option that is used most often, then the rafter system itself can be made in two main versions:
It is often used combined option. For example, it is used in the construction of a gable roof. In this case, extensions extend from the main building at right angles. Main house covered with a roof using a layered rafter system. Side extensions, since they are usually not wide, can be “covered” with a hanging structure. 
Installation procedure
Correct installation of the rafter system is carried out in a certain sequence. A lot depends on the characteristics and type of roof. The simplest option is flat roof. In this case, no special skills are required. It is enough just to lay the beams, creating the necessary slope, and install the sheathing and roofing materials.
The second most difficult is considered to be a gable roof. This is exactly what we will talk about. Knowing the sequence in the case of a gable roof, you can easily navigate other options.
The sequence of actions when installing the rafter system is as follows:
At the end of the installation of the rafter system, the sheathing is installed. Should be laid first waterproofing material. If this is not done, then wooden elements get wet and quickly fail. 
There are some features of installing a rafter system on a house built of wood. Firstly, in this case the Mauerlat is not used. Secondly, the rafters themselves are necessarily attached to the upper crown of the walls using a sliding method. This is necessary due to the nature of wood. It begins to dry out over time. If the rafters are fixed in a rigid way, then the entire system will definitely fail and the roof will simply collapse.
Features of installation of different types of roofs
There are a lot of roofing options. Each owner chooses according to his preferences and tastes, and the features of the house itself are also taken into account. Depending on the type of roof, the installation of the rafter system is carried out with some differences, namely:
Gable and pitched roof you can build it yourself. To install a rafter system, you need some carpentry skills and clear calculations and planning of your actions. All calculations can be easily done using special programs on the Internet. There you can also find installation instructions.
For other roofing options, quite a lot of experience is required. That is why their construction is most often trusted to professionals. Of course, in this case the cost of the roof will increase significantly. But you will have a guarantee that everything is done correctly. This means that the house will be reliably protected from external influences and will last for decades.
Construction of the base for roofing covering is considered the smallest part of the work in the list of main construction activities. The foundation, construction of walls and partitions usually require a lot of effort and material investment. Nevertheless, the roof is the most important component in the design of any building, so this activity should be approached responsibly. Loads in the form of precipitation, gusts of wind and other mechanical influences can disrupt the tightness and integrity of the roof. Therefore, you should carefully approach the creation of the foundation on which the roof will be fixed in the future. The installation of rafters and sheathing is considered by experts as the most significant stage on which the reliability of the roofing depends. There are different approaches to installing this part of the structure, the choice of which is largely determined by the characteristics of the final flooring.
Installation of rafter system
Even a well-installed sheathing will not provide the necessary load-bearing function if it was installed on a weak one. Therefore, it is important to install it correctly.
First of all, the mauerlat is attached - beams that will act as the basis for the sections of the structure. The best option involves the use of a solid Mauerlat, secured. Then they are secured to the installed elements. Then you can begin assembling the sections. The choice of configuration for their location and fastening to each other is determined by how the roof sheathing of the house will be installed.
Based on the general plan, a drawing is drawn up, after which the structure is assembled on the ground. Ready system must be lifted onto the roof - usually this is done using a winch. When one of the sides is pressed as closely as possible to the base of the building, it can be freed from the cables and secured with ties and crossbars. The basis of the fastening will be the corners with bolts, which will allow you to securely fasten the rafters to the Mauerlat.
Laying the under-roof membrane
A common mistake made by many inexperienced roofers is to ignore insulation measures. The tightness of the roof, the absence of dampness in the attic and the overall comfort in the premises depend on the quality of this stage. After installing the rafters, you can begin laying the appropriate protective materials. Regardless of the technique used to install the sheathing, the structure can be insulated in the lower part using this layer to ensure vapor permeability and waterproofing. But it may not be the only under-roofing material - sometimes membranes are supplemented with insulation. The process of laying such a coating is not particularly difficult. The membrane is supplied in the form of rolls, which are spread at the workplace and laid over the entire area of the rafters. The strips can be laid overlapping and fixed with glue or special hardware.
The nuances of choosing wood for sheathing
To the selection of materials for load-bearing structure You should approach the roofing area carefully, and this is especially true for wood. It is advisable that the installation of the sheathing be made of coniferous material, for example, spruce and pine. This is an easy-to-work wood that will provide flexibility and strength during the operation of the roof. It is important to consider the type of material. Of course, the first category would be the ideal choice, but if financial possibilities exclude such a purchase, then you can limit yourself to the second category. However, such structural elements should first be treated with antiseptics.
Another significant selection parameter is humidity. If protection is expected from the inside in the form of a plasterboard coating, then you can use wood with a moisture content of no more than 20%. If you plan to install sheathing, part of which will have direct access to air, then the use of wood with a moisture content of more than 20% cannot be ruled out.
Installation of sheathing under siding
For installation of siding panels you should prefer wooden sheathing. This choice is justified by the flexibility of the material, which will not allow the outer coating to deform. During the installation of elements, it is important to maintain uniformity, that is, all slats must be in the same plane. The fastening itself is carried out with hanging brackets or ordinary nails. If the base has unevenness, then the position of the frame can be adjusted using wedges. As a rule, the installation of sheathing under siding is carried out with an element increment of 20-30 cm. But in each case, this distance should be calculated individually. The larger the working area, the longer the indentation - this is the basic rule that guides roofers in such design.
Installation of lathing under metal tiles
The complexity of constructing a frame for metal tiles is due to the fact that the profiles can have different corrugations and standard sizes. By the way, siding in this sense is more standardized. If planned continuous lathing, then it is better to use boards with parameters 3.2 x 10 cm or bars 5 x 5 cm. Fixation is carried out close to the base in increments of 10 cm. Such a short indentation is due to the fact that corrugated sheeting is one of the heaviest roofing materials. Accordingly, the installation of sheathing under metal tiles should take into account high loads on the design. For fastening, you can use nails 3 mm thick, and their length should be twice the cross-section of the board. A special feature of installing a frame under metal tiles is the wide presence of metal fittings for fastening. Various brackets and corners, which act as an additional means of fastening, are most common in large-area roofs. If a standard gable system For small house, then it is quite possible to get by with slats, which are fastened at frequent intervals using nails.
Installation of sheathing under a soft roof
The installation of a soft roof can be called the most demanding and even capricious type of such work. This material is laid on a flat, continuous flooring, so the lathing will be carried out in two stages. First of all, the frame is mounted. Its features will be a frequent rack pitch and extreme accuracy. Next, a smooth protective covering, which will subsequently fall on soft roof. If the installation of roof sheathing can be done using the same bars and slats, then chipboard, plywood or other wood-based material with similar characteristics should be used as additional flooring. The main thing is that the rafter structure is initially well insulated. In addition, the ends of the base must be rounded to ensure a smooth transition of the decorative roof.
Features of installation of plastic sheathing
Metal is usually considered as an alternative material for sheathing. Wood does not always achieve the required strength, so it is replaced profile elements. However, in some cases it is also possible plastic sheathing, the installation of which involves some differences, but in general the fastening technique remains the same. Fixation is carried out through special holes in elements using bolts or self-tapping screws. But the peculiarity of plastic panels for sheathing is that their design allows for more reliable fastening to the rafters using a system of grooves. Exist different models such elements that should be selected specifically for the needs of a particular roof.
Installation of counter-lattice
In design, this type of sheathing is in many ways reminiscent of a traditional frame formed by slats or boards. Its fundamental difference lies in the additional strengthening of the system due to insulation with roofing felt. It has already been noted that the design must include insulation and a vapor-tight membrane. But in this case, the function of protective roof barriers is enhanced. That is, roofing felt or other material with similar properties is first laid, and then the sheathing is installed on the rafters on top of the insulating flooring. The configuration of the arrangement of elements can be either sparse or continuous. The main thing is to provide sufficient space under the roof to prevent the formation of condensation. This is especially important when fixing, which is damaged by accumulating moisture.
Conclusion
The variety of materials for creating roofing determines the requirements for both the rafter system and the supporting frame. In turn, the installation of the lathing cannot be carried out without taking into account the operational requirements for the final coating. For example, metal decks require a higher degree of structural reinforcement. In this case, it is important to provide quality material to create sheathing that can withstand weather conditions. For siding - on the contrary, physical strength is not so important, but the flexibility of the frame comes to the fore, which is ensured by correctly selected slats.
The gable roof is one of the most popular in individual construction. It is quite simple to erect, it takes little material, and it provides good protection from rain, snow and wind. The construction of a roof can be considered as a separate stage, consisting of its design, calculation necessary materials, installation of the rafter system, insulation, and laying of roofing material.
The rafter system is the skeleton of the roof, and only with its correct calculation and fastening is it possible long service the entire roof, without distortions, leaks and collapses. It is best to entrust the installation of rafters to a team of professionals, but if this is not possible, it is realistic to do it yourself, but in any case, you cannot do it without assistants.
Material for rafters
To most accurately calculate required amount material, it is worth drawing (on your own or in a special program) a plan of the rafter system and its layout. Considering the length of the boards and beams, the elements can be arranged in such a way that the amount of waste will be minimal.
For the manufacture of rafter beams, wood of the highest category is used - without knots and cracks. Standard sizes material 50 * 150 mm with a length of up to 6 m, but if the beams must be more than 6 m, then boards 180 mm wide are needed to avoid sagging.
Attention should be paid not only to the quality of the wood, but also to the fastening elements. Self-tapping screws for fastening the structure must be from a trusted manufacturer, with spacers of 2 mm or more. You also need to take into account the need for antiseptic and fireproofing of wood.
When erecting rafters you will need the following tools:
- measuring instruments - an accurate and long tape measure (preferably 6 m or more), a level, a cord for plumb lines, a pencil for marks,
- hammers and nails, nail puller,
- carpenter's knife, hacksaw, saw (or chainsaw),
- drill, screwdriver and screws,
- axe,
- templates for fastening rafter structure elements at the correct angle,
- stop for installing rafters – a 6*6 cm beam with a 40*40 mm corner attached on both sides,
- cables for lifting rafters.
Types of rafter structures and its elements
The rafter system for large and small roofs will be slightly different in design, and its design also depends on the presence of a support beam and its location, and the angle of the slopes.
Main elements of the rafter system:
- Mauerlat – support beam 150*150 mm thick, for more even distribution of the load on the walls,
- rafter leg,
- rafter leg, or crossbar,
- rack,
- purlin - a 50*200 mm board to which the rafter legs are attached at the top,
- sill.
Rafters can be hanging or layered. Hanging ones are attached at their ends to the walls of the house and the ridge of the roof; if they are long, it is necessary to compensate for bending and compression loads with ties connecting the rafter legs. Layered rafters can be erected in houses that have load-bearing walls inside and you can use a support beam on which the rack is attached. The ends of the rafters rest on this post and on the external walls of the house, the middle part is supported by supports. It is optimal if the structure has both hanging and layered rafters, this makes the roof more durable.
Installation of rafters
Stage 1 - installation of the Mauerlat
First of all, the Mauerlat is attached to the external walls using anchor bolts. It is desirable that it be solid or with a minimum of connections, this will increase the strength of the structure. The Mauerlat must be positioned absolutely level, since the accuracy of the installation of the entire roof depends on this. If necessary, gaskets can be inserted under it and the protruding parts are pressed together. In the future, rafter legs will be attached to the mauerlat.
Stage 2 - run
Using a rafter design with a purlin increases the reliability of the roof and simplifies assembly, since each pair of rafters can be mounted separately. The purlin is installed at the highest points of the front walls and secured using metal corners and anchor bolts. Its ends must be waterproofed.
Stage 3 - assembly of rafter sections
Before assembling the rafters, blanks are cut, trying to use the material so that the amount of waste is minimal. If necessary, the boards can be lengthened, paying attention to the reliability of the connection, for example, using overlays or overlaps. It should be located at least a meter from any of the edges. It is better not to place the connection exactly in the middle, since load bearing capacity legs drops, optimal location- a third of the total length.
The rafters are assembled according to the drawings; templates (angles at which the elements should be positioned to each other) greatly simplify this work. The easiest way is to assemble the rafter sections on the ground, then lift them up. However, this may require a winch or several helpers.
First, all elements are laid out relative to each other as they will be located in the finished section. Angles and gaps are carefully adjusted. Then the linings are attached to the top of the rafters with nails, and the legs are connected in the middle with ties. At least 5 nails must be driven into each nail joint. Temporary slats are screwed to the bottom of the legs.
Stage 4 - installation of the rafter system
The rafters are raised gradually. First at 30 degrees, then with the help of insurance and cables up to 60. At this stage, reverse side The crossbars and ties are nailed to the structure secured with cables. Then the section is raised to a vertical position, which is checked using a level and the structure is fixed with bolts and angles to the purlin and to the Mauerlat.
There are two ways to set the rafters:
During the first, the first and last sections are installed, a cord is pulled between them and all other parts are mounted along it.
In the second case, the rafter sections are installed above one half of the house, and the second half of the structure hangs on the purlin and leans against them. Next, the first section is mounted with opposite side, and gradually the rest, this process resembles closing curtains and ends in the middle of the roof.
After installing the rafter system, you can begin making sheathing, vapor barrier and insulation.
Construction own home– this is always an expense: starting from the project and ending with its implementation, you can’t do it anywhere without the help of professionals. But is this really so? Isn't it possible to do most DIY work? You can if you use the tips from our website!
There is a lot on the resource, like reliable basis any building. But, in addition to a stable foundation, the coziness and comfort of staying in the house is influenced by the fact that it does not leak and helps to maintain heat in the room.
Any roof structure cannot do without high-strength rafters, and their assembly is one of the most labor-intensive tasks when building a monolithic or private house. Frame for new roof You can buy it at the nearest woodworking sawmill, and you can install it yourself, observing all the technological requirements and features of the different configurations. Next, we will consider the main elements and methods of installing rafters on the roof of a private house.
Elements of the truss structure
Mauerlat- the main component of the entire system, a kind of foundation that is installed along the perimeter of the walls and creates an optimal load balance, protecting the structure from involuntary movement during strong winds or heavy rainfall. The Mauerlat can be made from planed timber; in some houses it can be replaced by the top frame of the walls.
Rafter legs – designed to hold a kind of sandwich. A sheet of sealant is laid between the load-bearing rafters, and a sheathing is placed on top of it.
Runs– solid beams that are laid level along the roof. Used to secure rafter legs. They are divided into several types: ridge girder (located in the upper part of the roof), side girder (located in the center of the supporting legs of the rafters).
Racks– take on little weight of the structure. Used to strengthen rafter and ridge stops.
Struts– are installed specifically to hold rafter legs. Mounted in an inclined position. Gives the structure additional strength.
Installation of the rafter system
To get started installation work on the construction of the roof of a private house, it is advisable to familiarize yourself with the theoretical part, from which you can learn how to correctly install rafters on brick or wooden walls. Let's consider the most common sequence of installation of rafter system elements.
Mauerlat installation
Before laying the Mauerlat on wooden walls, you can add one log around the entire perimeter to increase the height of the ceiling. It is advisable to place a binding wire under the top logs that will serve as the base, with the help of which it will be attached to the base of the wall. An easier way is to secure the base with large anchor bolts.
First comes the waterproofing film or roofing felt. Next, we lay out the finished workpiece along the entire perimeter of the walls. In some cases, the length of the beams may be shorter than the walls, in which case they need to be leveled.
How to connect the Mauerlat After installation, we check the geometry. A laser level is ideal for this operation.
This operation should not be neglected - the slightest inaccuracy of 1-2 cm threatens poor-quality assembly of the entire rafter system, which can lead to unplanned roof repairs as early as next year.
Good to know. The most in a simple way The test is considered to be a rope or fishing line. With their help, you can measure the distance of one diagonal (from one corner to the opposite), record it and compare it with the other, and if the result matches, then everything was done correctly.
We fix the corners of the Mauerlat.
We secure the entire structure with wire, anchor bolts or studs. For fastening with studs and anchors, holes should be made in advance. A low-speed electric drill can easily handle this. It is better to screw in the bolts in several stages, alternately on each side.
We do the correct installation of rafters
Rafters Before proceeding with the installation of rafters, it is advisable to decide on the type; there are only two of them - hanging installation of roof rafters and inclined. Their main task is to fasten and hold all elements, and the difference is the number of supports.
Inclined ones have 2 or 3 pieces. For small buildings with small spans, an inclined installation system is used lean-to rafters. Gable roofs are used for domestic or public premises, which are equipped with additional load-bearing partitions and columns.
In the area of the base of the beam, the rafter legs should fit snugly against the mauerlat, and at the top - into the ridge girder, which is attached to racks mounted on the lower girder. It is better to make the connection on pre-prepared notches using metal clamps or staples.
Hanging ones rest on load-bearing walls in two places; additional supports are not used.
Therefore, if the planned slope is less than 45 degrees, horizontal pressure there will be more vertical, which means it’s worth thinking about emergency reinforcement. Therefore, before starting work, it is necessary to carry out all the calculations and decide how to install the rafters in your case.
Rafter system for the future attic The most common method of fastening is metal or metal ties. wooden structures. The location of their installation is selected individually and directly depends on the desired functionality attic space. For example, if the roof will be used as a roof, the screed location should be at the base of the rafters.
Installation of load-bearing rafters for a gable roof
To create reliable fastening the entire roof, which can withstand heavy loads, must use a combined installation method, i.e. The rafters will be installed using two technologies - inclined and hanging.
High-quality beams with antiseptic treatment are best suited for installation. The most common size is 49.9*149*5000 mm. If the length of the beam is greater than specified, it is advisable to increase the height of the supporting beam to 180 mm. The installation of the rafter system should be carried out in a parallel manner, that is, having mounted the rafters on one side, we immediately install them on the opposite side.
Preliminary marking and drilling of holes for fastenings is best done on the ground.
In order for the supports to be as stable as possible, it is advisable to make lower grooves along the diameter of the Mauerlat.
Having selected the upper section of the intersection, we proceed in the same way and make an insert equal to half the diameter of the beam.
When fastening with an overlap, the upper fastening should be obtained without additional protrusions.
In order for all the grooves to be the same diameter, it is necessary to prepare a mortise template. The most common material for its manufacture is plywood or thick cardboard. According to a previously drawn up drawing, a model is cut out of plywood in two copies, nailed to the beam on both sides and outlined with a pencil. The insert made according to this principle will be dense and as even as possible.
It is advisable to make the cuts as simple as possible, since intricately cut connections can be absolutely unreliable.
If possible, the mounted planes should be perpendicular to the load forces that may occur along the wooden elements.
After creating the structure, it should be securely fastened to the Mauerlat. Regular nails or special anchors are suitable for this. The next step is to determine the minimum distance of the rafters from each other.
To determine it, look at the table.
| Rafter leg length, m | Distance between adjacent rafters, cm | |||||||
| 110 | 140 | 175 | 213 | |||||
| Thickness of the rafter leg, cm | ||||||||
| Bruschi | Logs | Bruschi | Logs | Bruschi | Logs | Bruschi | Logs | |
| Less than 3 | 8 * 10 | Ø 10 | 8 * 13 | Ø 13 | 9 *10 | Ø 10 | 9 * 16 | Ø 16 |
| From 3 to 3.5 | 8 * 13 | Ø 13 | 8 * 16 | Ø 16 | 8 *18 | Ø 18 | 9 *18 | Ø 18 |
| From 3.6 to 4.2 | 8 * 16 | Ø 16 | 8 * 18 | Ø 18 | 9 *18 | Ø 18 | 10 *20 | Ø 18 |
| From 4.2 to 4.9 | 8 * 18 | Ø 18 | 8 * 20 | Ø 20 | 10 *20 | Ø 20 | – | Ø – |
| From 4.9 to 5.7 | 8 * 20 | Ø 20 | 10 * 20 | Ø 20 | – | Ø – | – | Ø – |
| From 5.7 to 6.2 | 10 * 20 | Ø 20 | 12 *22 | Ø 22 | – | Ø – | – | Ø – |
Trying on rafter legs
Below we consider the main aspects that will influence the choice of the cross-section of the rafter leg:
- We find out what constant pressure will be on the bars.
- The covering material used in a particular application.
- The desired angle of inclination of a pitched or gable roof, which is easy to calculate if you use the tips from.
- Dimensions of the house and the expected complexity of installation.
- Climatic conditions of your area. The calculation takes into account the level of precipitation in summer and winter.
- The material and quality of the rafters themselves. The most the best option there will be bars obtained from coniferous species trees. But sometimes you can stumble upon a fake, so it is better to select higher quality varieties so that the natural origin of the material can be determined by the wood.
The main characteristic of the wood used is its moisture content. An appropriate level should be within 22 percent. If you are wondering how to install rafters with high humidity? The answer is no way! They need to dry thoroughly. The whole reason is that excessive moisture will evaporate over time, and the wood will shrink, which will lead to its deformation and change in size, and this can lead to more Negative consequences, for example - a violation of tightness.
Let's move on to trying on the legs. There are several reliable fastenings in use today. They can be used for any type of roof. The reliability and correctness of connecting the rafters to the Mauerlat will depend on their execution:
- Sliding;
- Hard.
For both cases, a varied combination of hanging and sloping rafters can be used.
The hard way used for standard structures that are installed without turns or bends. To use it, it is advisable to apply marks on the bars in advance and make appropriate cuts, followed by attaching the rafter leg to the mauerlat.
sliding(very often called free fastening) has several stages of fastening. This is done in order to leave a certain margin for the frame to settle; it can be used in conjunction with poorly dried rafters.
It's hard to overestimate the importance correct installation rafters for the stability and durability of the roof.
Thus, by applying the basic knowledge gained from this article, you can not only control the process, which is led by professionals, but also carry out most of the work yourself, while significantly reducing costs and saving time and nerves.
Good luck with your construction!
Roofs today country houses can have almost any shape. Moreover, almost all of them can be created with your own hands, but they have one thing in common: similar designs and the fact that installation of the rafter system is a mandatory part of the work. This issue raises many difficulties, so in this article we will present the design features of the roof truss system, indicate the rules and nuances of implementation full list work on its construction.
Mauerlat is the first thing you should think about when planning to install rafters. It is the base to which part of the load is transferred by the rafter legs. In addition, this design is designed to evenly distribute the weight of the roof over the top of the walls of the house.
As a rule, the Mauerlat is a log or beam that is laid around the perimeter external walls. It is worth saying that this is not the only option for constructing bases for rafter legs, but other methods turn out to be much more expensive.
When installing the rafter system, it is the Mauerlat that allows you to achieve required parameters roof bases with minimal costs, therefore this technology has become widespread in suburban construction.
Mauerlat can be treated with various impregnations, but moisture ingress can still cause a decrease in its service life. To prevent such a situation from arising, waterproofing is used, which is usually made of roofing material laid under the timber in a couple of layers.
Before installing the rafter system, you need to prepare a place for installing the Mauerlat. Usually the basis for it is reinforced belt, having a small indentation from the wall of the house. As a mauerlat, you can use timber impregnated with antiseptics, with a cross-section of 10x15 cm. It is better if the wood is hardwood.
The timber is first laid out along the perimeter of the roof between the gables. Here you need to make sure that all elements of the roof base lie at the same distance, and check their position by level.
Roof raftering can only be done after the timber base is securely fixed. Several methods can be used for this today, but the most popular are anchor bolts, which are strengthened into a reinforced belt during its pouring. For installation, holes are drilled in the timber to allow the Mauerlat to be secured to the anchors using nuts and washers.
At self-construction It is not easy to achieve verticality of anchors poured with concrete. This problem can be solved simply: when installing the rafter system, it is necessary to lay a long board along the group of bolts, and set their position using a square.
After the concrete has gained the proper strength, the Mauerlat is installed. In order to avoid distortions during this procedure, it is recommended to use stands made of small planks located under the entire beam. They are taken out one at a time.
What types of rafters are there?
Before the installation of rafters begins, you must already decide on their type. In fact, there are only two options - layered and hanging. The task of the rafters is to hold all the elements of the roof. If we are talking about a small building, then it is enough to use simple rafters, however, to cover extended rooms they are already using roof trusses, which are formed through the use of various additional elements.
The installation of the rafter system is carried out in accordance with the slope of the roof, the expected load from snow and wind, and also takes into account the type of roofing and the functions of the attic.
Hanging rafters are a structure that rests on only two points, for example, on the walls of a building, and no intermediate supports are used. Obviously, in the case when the angle of inclination of the slopes is less than 45 degrees, the horizontal component of the force transmitted to the walls will be greater than the vertical, which means that certain measures will need to be taken. Usually, a way to neutralize such an impact is developed even before installing the rafters. Most simple option are the ties that connect the rafter legs. These can be wooden elements or metal structures. The location of such amplifiers depends on the purpose of the attic space. For example, if it is necessary to create an attic, then the tie rods are located at the base of the rafters, and in other cases they may be higher.
The higher the tie is located, the stronger it should be. The same point must be taken into account when choosing a method of connection to the rafters.
When installing a layered rafter system, a third point of support is required, which is usually a rack mounted under the ridge. The peculiarity of this design is that it can only be used where there is a central load-bearing wall or some reliable supports passing under the ridge. Otherwise, its use is inappropriate.
Pre-installation process
Before making rafters, you need to stock up on everything necessary to perform work at height. Of course, someone will say that 3-5 meters separating the roof country house from the ground - this is not the most a big problem, however, it is worth considering that you will need to lift and store tools and structural elements. Best suited for this purpose scaffolding, but we must not forget about individual insurance, especially when the roof of a two-story house is being raftered.
During preparation, you need to take care of creating drawings of the roof structure. Even if the plan is only gable roof for small country house, the drawing will avoid any mistakes. It goes without saying that even a team of professionals will not undertake to build more massive and complex structures without a design.
Making rafters
For the role of rafters, timber with a cross section of 50x200 is usually chosen, but before the installation of the rafter system is carried out, a number of calculations must be made. First of all, you will need to calculate the degree of influence of wind load, estimate the possible amount of snow on the roof in winter and also include it in the calculations.
The installation technology is quite simple and includes the following steps:
- Climb. With the help of scaffolding, the prepared timber is lifted onto the roof.
- The lower ends of the legs are cut so as to turn the mauerlat into a stable support. Each element is marked with a marker so that there is no confusion during the installation process.
- The lower ends are set in place and secured with nails.
- The connection of the rafters in the ridge is carried out so that their parts overlap, forming a single plane. To do this, you need to trim and then fix the structure with nails.
Trimming at the junction of the upper part of the rafters is carried out as follows:
- First, the elements are applied to each other, after which markings are made. Then half the thickness of the timber is cut along the marked contour.
- The next stage is carried out on the ground, for which a template is created based on one pair, which allows you to connect the remaining rafters in the same way.
- When all the elements are prepared, the two outer pairs are mounted, after which a thread is stretched between them, allowing the selected level to be maintained.
- Before making the rafters, the Mauerlat is marked, which allows you to keep the distance between the structural elements constant. Typically, the system pitch is selected within 1 m.
- In the event that there is a deviation in height from that specified by the tensioned thread, it is better to regulate it by placing small flat boards under the rafter legs.
- In order for the resulting “triangles” to be located vertically, it is necessary between them upper parts maintain the same distance as between the lower ones. To do this, it is enough to use a board on which the marks made on the Mauerlat are transferred.
- If the installation of rafters hanging type If done with a significant distance between the walls, it is recommended to use tie-downs. Lightly loaded structures can be connected by a jumper near the top. The resulting element is called a ridge knot.
The tightening can be made from several boards connected to each other. Such a jumper turns out to be quite strong, and also has required length. Installation of the rafter system can be done using nails, studs and bolts. The distance between the puffs is controlled in the same way as between the upper parts of the rafters.
A long tie can bend under its own weight, so it is necessary to use a board to connect this element and the ridge of the rafter pair.
Creating eaves overhangs
Cornice light is very important element any roof, but it is performed after the installation of the rafters is completed. To obtain an overhang, you will need to extend the rafter leg by using a board (filly).
In order for the eaves overhang to divert melt and rainwater from the house and protected the walls from getting wet, a projection of at least 40 cm will be required, and the best option would be more than half a meter in length. A filly is a board that can be even thinner than a rafter leg. It is fixed with a small gap on the nails, and it is better to bend the ends protruding from the other side.
If possible, consider creating eaves overhang necessary before making rafters. In this case, it becomes possible to implement another option - to use a longer beam for the rafter legs, which will make it possible to carry it out as a cornice overhang.
The rafter legs, which were fixed with nails, after completion of all work can be transferred not to temporary, but to permanent fastening. For this, a so-called shank, which is a strip of metal, is suitable. You can wrap it around the timber and secure the ends with screws or nails. This fastening will help keep the roof in place even when the wind is very strong.
Anyone who knows how to install rafters correctly can recommend another method. This is a wire fixed with inside walls Typically, for such purposes, steel wire with a diameter of 4..6 mm is used, tied to metal pipes driven into the wall.
Log rafters
Creation truss structures This type is made from debarked wood with a diameter of 18 cm. It is desirable that the logs themselves are smooth, without curvature, rot and wormholes. Minor irregularities are eliminated by working with an ax along the cord.
The advantage of this approach is that there is no need to splice the rafters along the length, since the size of the logs is usually sufficient. Maximum length round timber can reach 6.5 m. When the spans are large, the tightening is carried out by a team of several logs. Struts and racks are made from scraps, but short logs can also serve this role. It is better to mark using a template made of metal or plywood. When the marking is completed, cutting points are created, which must be cleaned with an ax.
Calculation of rafter cross-section
Splicing rafters along the length is not the only difficult point, since even their cross-section will need to be calculated. IN general case There are three reasons that influence the cross-section of the beam:
- Load. Here we are talking about the weight of the future roof and the mass of the snow cap.
- Span size. The longer the span, the more durable the timber will be required.
- The angle of inclination of the slopes.
Before making rafters, you need to carefully analyze information about the construction and climatic conditions in the region, since the classic option may not always be suitable. The most common situation is to use a slope of at least 30 degrees and a pitch of more than 1.2 m.
This article described how to make a rafter system, and also discussed those points that cause the greatest difficulties. If necessary, it can be used as a support material.
