To protect the interior of the house can be used in a variety of types of roofs. For example, they look very nice, for example, four-slope, hip, multi-forceps. However, most often, owners of private houses erect the usual gable roofs. This shape of the roof is popular primarily because of the ease of assembly, as well as because of reliability. In addition, under the roof of this variety there is enough space for a large attic or attic.
Design features
Installation of the rafter system of the gable roof, like any other, is carried out on the Mauerlat. Also, the design of such a roof may include:
rafters;
racks, runs, beds;
horse;
crate.
To protect the rafter system from moisture, hydro and vapor isolators are used. They are usually installed on top of the insulation. This material is necessary to protect the attic or attic from the cold. Of course, at the final stage, the frame of the house is sheathed with roofing material.
Mauerlat for a gable roof: installation features
This structural element of the roof frame is usually assembled from a very thick beam (section 150-200 mm). After all, it is he who serves as the main support of the roof. Mauerlat is laid on top of the walls of the house. If the latter are assembled from gas or foam concrete blocks, a reinforced concrete belt is pre-equipped. To fasten the Mauerlat, anchor bolts are poured into it. Under the gable roof, the Mauerlat is usually laid only on two walls - parallel long. On block, log and panel houses this element is not used. In this case, the upper crown or harness serves as a Mauerlat.
Roof rafters
This is one of the most important elements of the roof. The rafter system is assembled in most cases using a material such as a bar 100 * 100 mm or 150 * 150 mm. Also, a board of 100 * 150 mm can be used under it. Before the erection of the rafter system, the material is cut so that at the top the legs adjoin each other or to the ridge as tightly as possible (cut at a certain angle). Also sometimes landing nests in the lower legs are chosen. This allows you to build a more reliable roof.
Wooden rafters can be attached to the Mauerlat, upper rim or harness in different ways. Sometimes they are fixed with a “knot” on three nails and a thick wire. But more often all the same, the legs are mounted on galvanized steel corners on both sides. This greatly facilitates assembly. At the top of the rafters are fastened to each other with metal jumpers or to the ridge to the corners.
On wooden chopped buildings, a beam (100 * 100 mm, 150 * 150 mm or 100 * 150 mm) is fixed by means of special additional elements - a "slide". This provides the mobility of the rafters. It is justified to use such fasteners primarily by the fact that when drying, the walls of the houses are able to sit down. Therefore, it is impossible to rigidly fix the rafter system (on nails or corners) in this case. Otherwise, it can simply lead.
Rafters of a gable roof: varieties
Sometimes the inclined beam of the roof frame can be attached only below - to the Mauerlat and above - to each other or to the ridge run. Such rafters are called hanging. But another type of frame is often used. In this case, an additional support is installed under the legs (along the entire length) in the middle of the ramp. As a result, the roof is "broken." Such gable roofs are called mansard roofs, and their rafters are called layered. This is the most practical type of roof of a country house. The distance between the rafters - both layered and hanging - is determined based on the thickness of the selected beam, the length of the slopes, etc. Usually, the step is 60-80 cm.
Subframe frame system
On houses of a large area, in addition to Mauerlat, an inclined roof beam can be based on girders, racks and lodges. The first are installed horizontally, the second - vertically. Lumber is called a beam laid along the beams of the ceiling. They are attached to it with a certain step along the entire length of the rack roof. Next, they set the ridge run. For this element, a 100x150 mm beam is usually used.
Skating run
Installation of the rafter system of a gable roof using this element is done quite often. And this is despite the fact that the roof in this case is more expensive. The fact is that the roof frame with the run is more reliable and better resists all sorts of loads.
This element must be installed in compliance with all applicable technologies. The accuracy of the roof geometry depends on how carefully it is mounted. When assembling a roof with a ridge run, first extreme racks are installed (along the gables). Next, an inelastic cord is pulled between them and verified according to level. Then, focusing on it, install all the intermediate racks. In this case, the ridge run fixed to them in the subsequent will be located absolutely horizontally.
Crate
It is also a very important structural element of any roof. The board for the crate is usually quite thick. Depending on the roofing material used, an option of 2.5-5 cm can be used. Too narrow or wide rail for the crate is not taken. In the first case, the boards can warp, in the second - crack. The optimum width of the material for the crate is 20 cm.
The step between the boards, as well as their thickness, depends on the type of skin chosen. Such a rarefied crate is arranged only under hard sheets. Under the roofing material and very thin metal mount solid. For such a crate, usually not a board, but sheets of thick plywood or OSB.
Thermal insulation layer and waterproofing
The design of the gable roof is such that absolutely any modern material can be used to protect its interior from cold. Most often, mineral wool is used to warm the attic or attic. Sometimes polystyrene foam is also used. In very rare cases, roofs are isolated by spraying polyurethane foam.
As a support under the mineral wool and polystyrene, the wire is pulled from the attic side. The sheets or plates themselves are installed directly between the rafters. Mineral wool is mounted simply by surprise. The cracks between the polystyrene foam sheets and the beam are sealed with special mounting foam and glued with tape. Steam and water insulators are fixed with a slight sag (2 cm) in a horizontal position at the final stage of assembly of the rafter system.
Roofing material
For roof sheathing, metal tiles, slate, ondulin, profiled sheet can be used. Sometimes roofs are equipped with roofing material. The roofs of expensive large cottages are often covered with clay tiles. In general, there are simply a huge number of types of roofing materials. Metal sheets are fixed on the slopes using self-tapping screws. Roofing material is glued to a continuous crate using bitumen mastic. She also missed the seams. Clay tiles are also attached to the roof with self-tapping screws through the holes in it.
Rules for the selection of lumber
Installation of the rafter system of a gable roof should be carried out using only the highest quality lumber. When buying them, you should adhere to certain recommendations. Lumber intended for the assembly of the roof frame must be dry. The permissible percentage of its moisture is 18%. Usually, woodworking shops sell material that does not meet this requirement. Therefore, before assembling the roof, it is advisable to dry the tree under a canopy for at least six months.
It is possible to erect a roof immediately after purchasing a timber and a board only if they are made from a "winter" forest. The fact is that in the cold season in the tree trunks sap flow stops. As a result, lumber made from such logs initially does not contain too much water.
When choosing boards and timber, in addition to their humidity, it is, of course, worth paying attention to their quality. The fewer knots in lumber - the better. As for the type of wood, most often pine is used to assemble roofs.
Another parameter that should be considered when buying timber and boards is their geometry. Materials should be perfectly straight. Use for the assembly of the roof "twisted" boards or timber is not allowed. Also, the material should not have too many cracks.
Rafter system protection
The construction of a gable roof is a procedure involving the use of various kinds of materials designed to prevent moisture in the beam and water entering the subroofing space. The most commonly used waterproofing material is a technical plastic film. Sometimes a special membrane is also used. Such material is much more expensive than polyethylene, but it also lasts much longer. Films of this variety can trap moisture entering from the outside, and at the same time pass through themselves the vapors coming from inside the house. This contributes to the fact that the heat insulator and lumber inside the roofing “pie” always remain dry. Which, of course, significantly extends the life of the roof itself.
Under the sheathing material inside the attic or attic, a special film is mounted, which is called vapor barrier. Sometimes special foil sheets can also be used instead. They cost more than the film, but, among other things, contribute to the preservation of heat in the attic or attic, creating a "thermos effect".
After the installation of the rafter system of the gable roof will be completed, proceed with its sheathing. Roofing material should be selected as carefully as possible. Indeed, the reliability of the roof depends on its quality directly. Therefore, when buying, first of all, you should pay attention to the reputation of both the manufacturer and the supplier.
Roof calculation: tilt angle
Of course, in order for the roof to turn out to be absolutely symmetrical and maximally durable, it is imperative to draw up a detailed project before assembling it. To this document it is worth attaching the drawings of the roof in frontal and profile projection, as well as the plan (top view).
The gable roof shape is also good because it is not difficult to calculate it. To do this, you need to determine the angle of the rafters, the cross-section of the material and its quantity. The first parameter is determined based on which roofing material is supposed to be used for cladding. So, for example, for a metal tile, the minimum figure is 12 grams. Ruberoid can be used on roofs with a slope angle of slopes of up to 15 gr. In this case, four of its layers are applied. When gluing the roof at 40 degrees, 3 layers are laid, and over 45 gr. - two. Ceramic tiles can be used on roofs with a slope angle of slopes from 22 to 45 gr.
If the roof is too flat, it can bend or even collapse under the weight of the snow cover. Very steep slopes are exposed to strong wind loads. Therefore, when choosing the angle of inclination should take into account the climatic features of a particular area. That is, the maximum wind and snow load in your region.
Which slope angle to choose when building a house with a gable roof in a particular area of the country, you can find out using the information from special tables. But in most regions of Russia, the optimal indicator is considered to be 35-45 grams. Mansard gable roofs are equipped in such a way that the angle of inclination of the upper rafters with respect to the horizon does not exceed 30 g.
Material calculation
Thus, it is not difficult to determine the optimal angle of inclination of the slopes. Once this option is selected, you can begin to calculate the roof frame. The first step is to calculate the required rafter length. Knowing the angle and length of the short wall of the house, it will not be difficult to perform this operation using the corresponding trigonometric function. To the resulting figure, add 20-40 cm to the eaves overhang.
Knowing the length and distance between the rafters (and their number), it is easy to determine how much timber should be purchased. To calculate the boards of the crate, you need to know the step between them. It should be borne in mind that on the ledge and at the ridge, two rows of material are stuffed solid. To calculate the number of sheets of heat insulator, film and sheets for cladding, you just need to determine the total area of the slopes. To the figure you need to add 10% for losses.
How much will the roof cost
In addition to the drawings, a cost estimate for the materials must be attached to the project. Having calculated their required number, you can calculate the total cost of the roof. For 2016, the approximate cost of materials for the roof is:
pine board 25x200x6000 mm (for lathing) - about 500-550 rubles / pc.;
timber 200x200 mm (Mauerlat for a gable roof) - about 1200-1500 rubles / pc. (6 m);
technical polyethylene film (80 microns) - 990-1 000 rubles. per roll (3x10 m);
vapor barrier - 400-500 rubles. per roll;
mineral wool "Ursa" - 1,500 rubles. (packing 2x9000 x 1200x50).
From roofing materials, the cheapest option is roofing material. A roll costs about 350-400 rubles. But most often, the owners of country houses cover the roof with metal tiles. The cost of this material is about 300 rubles. per sheet.
What tools are needed
To install the rafter system, you will need a hacksaw (or electric saw), a screwdriver and a hammer. To cover the roof with metal sheets, among other things, you will need to prepare sharp scissors for metal. It is impossible to cut the material with a polymer coating with a grinder, otherwise the upper, protective layer of the sheets may be damaged. As a result, the roof sheathing will begin to rust very quickly.
If it is decided to cover the roof with roofing material, it is worthwhile to prepare a barrel for melting bitumen and a stick with a thick rag wound on it. You will also need several buckets.
Of course, for the installation of the roof you will need a reliable staircase, and possibly bridges brought down from the boards. To install the metal tile, it is advisable to also prepare shoes with soft, but non-slippery soles.