Roof frame: installation technology

When erecting a roof, the “first violin” in the entire structure is played by the roof frame. It is on the frame that the main mechanical load falls, which means that the requirements for the strength, reliability and durability of the frame are the highest. Roofing material, insulation and waterproofing can be very different, but if the frame is built with flaws - write wasted: such a roof will not last long.

Very often, the construction of a roof frame confuses novice craftsmen. However, if you figure it out, then there is nothing impossible in this task, you just need to choose one of the proposed house roof design and get down to business.

With the proper approach, correct calculation and good theoretical preparation, the frame part of the roof for a small house can be erected even alone.

At the same time, you will not only significantly save financial resources that would inevitably be spent on wages for hired craftsmen, but you will also be able to control the process of erecting the frame.

And this, in turn, means that the design of your roof will not give you unpleasant surprises at the most inopportune moment.

In this article we will tell you how to make a roof frame yourself, using only the most common tools and materials.

For example, we will take the frame of the most common gable type roof. But if you master this technology, then you can easily build roofs of a different design (hipped, broken, shed) - it will be enough just to take into account the features of a particular design.

Choosing the type of truss system

The first thing we need to decide is the type of truss system. Any rafter system consists of two rafter legs connected to each other at the top.

In the lower part, the legs are connected by a lower screed, which can also serve as the basis for an attic floor. However, in the structure of such a system, nuances are possible.

The frame of the roof of the house can be built on the basis of two types of truss systems: layered and hanging. Both layered and hanging rafter systems can be used in private construction.

How to choose a system for building a frame?

The choice of the truss system is mainly due to the design features of the building itself. If the distance between the external load-bearing walls does not exceed 6 m, you can install a hanging truss system.

The peculiarity of this system is that the rafter legs rest only on the side walls of the house - and with a large width of the building, a rather dangerous sagging of the building rafters occurs under its own weight.

A more reliable layered system is used when the distance between the external load-bearing walls exceeds 6 m, but in the room itself there is an internal load-bearing wall located in the center of the building.

In this case, you can get away from sagging rafters by installing an additional support.

Choosing materials for the frame

What do we need for the self-construction of a gable roof frame.

Rafters - the key node of the frame - we will build from wood. To do this, we need to purchase an edged board 50x150 mm, as well as a bar 150x150 mm.

It is optimal if the wood is coniferous, winter harvesting, and one from which resin has not been previously drained (resinous substances in the composition of wood significantly extend its service life, acting as a natural antiseptic). Also very important are the conditions in which the tree was stored before purchase, and the degree of its drying.

When examining boards and beams, it is necessary to pay attention to the possible marriage of wood: delamination, cracks, traces of damage by woodworms.

Materials on which these signs are found should be rejected - their use in the construction of the roof frame is unacceptable.

Note! Roof frames can be made not only from lumber, but also from a metal channel or reinforced concrete structures. But in this case, the roof turns out to be quite heavy, and we are no longer talking about its independent construction.

In addition to the rafter legs, girders and racks that make up the rafter system, the attic floor is included in the roof frame structure, as well as the counter-lattice and crate.

If the attic space will be used for its intended purpose (i.e. as an attic or warehouse), then a 50x150 mm board is sufficient for the construction of an attic floor.

If the attic space will act as an attic (i.e. living space), then the floor should be more durable: for its installation, we need a 150x150 mm timber, which is laid directly on the Mauerlat. The use of such a beam allows you to achieve sufficient strength from the attic floor.

For battens and counter battens, we use a thinner beam. A square bar 40x40 or 50x50 mm is quite suitable. Beams of this thickness are strong enough to support the weight of almost any roofing material.

When choosing beams for lathing, you need to strictly monitor their straightness, because the slightest deviation from a straight line can significantly complicate roofing work.

Also, a perforated profile made of galvanized iron can be used for the construction of battens and counter battens.

In addition to materials for the construction of rafters, ceilings and battens, we will need:

• Threaded metal studs for fastening the Mauerlat (support beam)
• Staples and brackets for attaching rafter legs to the Mauerlat
• Fasteners (wood screws, studs with a diameter of 8 and 10 mm) for connecting the rafters to each other
• Galvanized nails

The set of tools required for the construction of the roof frame is quite standard: you will need hammers of different sizes, a drill for drilling holes, a saw (or a grinder) for cutting the rafters to size and giving them the desired shape, a carpenter's ax, planers - in general, everything which is likely to be found in your tool cabinet anyway.

Particular attention should be paid to the measuring tool, because without an accurate level, plumb line and tape measure, you are unlikely to be able to set the rafters evenly at a sufficiently large distance.

Frame wood protection

Before proceeding with the construction of the truss system, it is necessary to ensure that all wooden parts of the roof frame are protected from fire and decay.

To do this, all the details of the rafters, floors and battens must be processed with two compositions:

• Antipyretic - a composition that reduces the combustibility of wood and protects the wooden part of the roof frame from fire
• Antiseptic - a substance that kills bacteria and prevents the occurrence of putrefactive processes in the wood of rafters and ceilings.

To apply protective compounds, it is recommended to use a brush, since it is difficult to achieve high-quality and deep impregnation when processing wood with a sprayer. We apply the composition in several layers, waiting for the drying of each previous layer.

Note! Some wood preservatives are quite toxic.Therefore, they should only be applied in a well-ventilated area or outdoors, and personal protective equipment (goggles and a respirator) should be used.

Protection of the roof frame is also possible after its construction. In this case, we process an already installed structure with a fire retardant and antibacterial composition, paying special attention to the impregnation of wood at the junctions of the beams of the truss system.

So, the type of truss system is selected, the materials are purchased and treated with a protective compound. It's time to start building the truss system.

Installing Mauerlat

The support for the frame of our future roof is a Mauerlat - a wooden beam that is laid on the load-bearing walls of the house. The main function of the mauerlat is to transfer and distribute the weight of the roof and the resulting loads (wind, snow, etc.) to the supporting structures.

Mauerlat is the basis for almost any truss system. An exception can only be the roof of a house made of timber or the roof of a frame house - when building a frame with your own hands, in these houses you will use the upper wall beam instead of the Mauerlat.

Most often (with the exception of the option that will be described below), a beam of 100x150 or 150x150 mm is used as a Mauerlat. It is optimal if the Mauerlat is laid “flush” with the inner surface of the wall of the building, and a brick barrier is erected outside the level of the Mauerlat.

To lay the Mauerlat along the perimeter of the building, we lay a monolithic concrete blind area.After the concrete is completely dry, we lay several layers of roofing material on it - it will provide a sufficient level of waterproofing, and will effectively prevent the wood from absorbing moisture from the concrete base.

Most often, the Mauerlat is laid according to the following technology:

• We install studs from a metal bar with a diameter of 10 mm or more into the concrete base. Studs can be installed both at the stage of erecting a concrete blind area, and later - by drilling holes in the concrete and fixing the studs in the holes with cement mortar. The first method is preferable, as it is less laborious.
• Mauerlat from a solid bar 150x150mm is laid along the blind area, and in places where the bar touches the studs, we make marks. According to the marks, we drill holes with a drill, the diameter of which corresponds to the diameter of the studs. We put the Mauerlat on the studs, while the studs should protrude from the timber by at least 10-15 mm.
• We fix the mauerlat on the studs with nuts, laying a wide flat washer between the beam and the nut to avoid damage to the wood when the nut is tightened strongly

Note! If you have a welding machine at hand and you have the skills to work with it, you can save on studs. Instead of studs, in this case we use reinforcing bars, and we simply weld the fixing nuts to them.

Another way of laying the Mauerlat allows you to somewhat facilitate the work.

Instead of timber, you can use two layers of boards 50x150 mm:

• We lay out the first row of boards along the perimeter of the walls, and fasten them with the help of anchor screws with a countersunk head and a metal sleeve. To drill holes in concrete or masonry, we use a hammer drill, having previously drilled the board with a drill with a conventional drill.
• We lay the second row of boards on top of the first row in such a way that the joints of the boards do not coincide, and in the corners we lay the boards “in dressing”
• We connect the rows with each other using 100 mm nails.

Such a fastening of the Mauerlat greatly facilitates the lifting of the material to a height - after all, the board is much lighter than the timber.

And the strength of the resulting structure is quite enough, especially if a relatively light roof of a frame house is being built.

Rafter installation

The next step in the construction of the roof frame is the installation of rafters. To make work easier (especially if you work alone), all processing of the rafters is done on the ground.

So it is more convenient to cut the bars to size, give them the desired shape using a template, cut out the necessary grooves and drill mounting holes. Only after that we lift the details of the rafters up and proceed to fixing.

The technology for manufacturing a roof frame with a hanging truss system is as follows:

• In the Mauerlat we make grooves for the installation of rafter legs. The distance between the rafter legs is determined at the stage of choosing the type of truss system, but in any case it should not exceed 1.5 m - otherwise the structure will have clearly insufficient rigidity.

Note! If you plan to insulate the roof, then it is advisable to coordinate the distance between the rafters with the dimensions of the insulation material. By laying whole sheets or pairs of sheets of insulation in the space between the rafters, you will significantly save time on trimming.

• We begin the installation of rafters from the gables - the end parts of the roof. Having installed the rafters at the ends, we stretch a cord between their skates, and we are guided by it when placing the intermediate rafters vertically.
• We insert the rafter legs into the grooves. To fix the rafter leg in the Mauerlat, we use complex fasteners: the transverse displacement of the rafter is limited by a steel bracket, and the longitudinal one is by a bracket with which the rafter is attached to the Mauerlat.
• When installing rafters, remember that the rafters must protrude beyond the perimeter of the building. The optimal value of this protrusion (it is called the overhang or the overhang of the rafters) is 40 cm - this is how the walls of the building are protected from water flowing down the roof. In addition to the protrusion of the rafter itself, the overhang can be equipped by building up the rafters with an additional thinner board - the so-called "filly". The "filly" is attached to the rafters with nails through a gasket - a short piece of board.

Note! The use of an additional board for arranging a roof overhang is not a design flaw: on the contrary, the use of a “filly” makes it easier and somewhat cheaper to design. It also makes it easier to repair the overhang - if necessary, it is enough to replace one or more "fillies", and not change the entire rafter beam.

• We fix the lower parts of the rafters with a strapping, which is used as the basis for the attic floor. The strapping bars are based on the Mauerlat.
• If necessary, build up the rafters (if their length is insufficient), we lay two beams overlaid with an overlap of at least a meter. To fix the bars, we use studs with a diameter of 8 to 12 mm.
• We connect the rafters to each other using studs, which we insert into pre-drilled holes. To prevent rotation of the rafters around the axis of the stud, each pair of rafters must be fastened with two studs.
• If the width of the roof is within 6 m, then we connect the hanging rafters with an additional transverse beam - a puff - in the shape of the letter "A". We make puffs from a board 50x100 or 50x150 mm, and fasten to the rafters with self-tapping screws. It is also possible to install a tightening of 3 x 30x100 mm boards located on both sides of the rafters.
• In the upper part, we fix the truss trusses with the help of a longitudinal ridge beam or ridge board.

• To strengthen the upper rafter assembly, you can connect the ridge beam with an additional puff of the board. This is done to avoid deflection of the puff with a large distance between the rafters.

Operations above roof rafters repeat for all rafter pairs. After all the rafters are installed, you can start arranging the crate.

crate

Roof lathing is of two types: solid and thinned. The choice of type of lathing is determined by the type of roofing material.

For the construction of a continuous crate, OSB boards or moisture-resistant plywood of sufficient thickness (10 mm or more) are used, the sheets of which are stuffed onto the rafters through the counter-rail. Solid lathing is suitable for laying soft and rolled roofing materials.

When erecting a thinned crate on do-it-yourself roof rafters bars or boards are stuffed, the distance between which depends on the dimensions of the roofing material used.

If austerity is required, an unedged board can be used instead of timber for this type of crate.

The thinned crate is stuffed onto the rafters from top to bottom. To increase the strength of the structure, we fill the first rows of the crate, starting from the ridge beam, without a gap.

After the crate is completed, you can begin work on the insulation of the roof, laying waterproofing and roofing.

Despite the complexity of the process, it is quite possible to build a roof frame with your own hands. And if you take up the work "fully armed", then you will invariably be successful.

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