Construction of houses

Diy pitched roof

In the construction of private houses, it is customary to use a pitched roof structure. This approach has many positive aspects. This is the possibility of arranging additional living quarters under the roof, and high-quality drainage of precipitation from its surface. But these advantages can be completely canceled if a high-quality pitched roof is not made. After all, it is the roof that is the shield that protects the roof structure from various atmospheric phenomena and prevents its destruction. Making a reliable pitched roof with your own hands is quite within the power of everyone who knows how to handle a tool, understands the structure of the roof, its nodes and materials.

Pitched roof structure

The creation of any building structure will be impossible without understanding what elements it consists of and how it is arranged. And the roof of a private house is no exception. In addition, knowing the design of the pitched roof, you can be sure of the correctness of the work performed, which will reduce possible errors to a minimum or completely eliminate them. In addition, knowledge of the design of the pitched roof will help to perform all the necessary calculations for the materials for its creation..

Pitched roof structure

The main nodes of the pitched roof are as follows:

  • rafter structure, consisting of a mauerlat, rafters, lathing and counter-lathing;
  • insulating layer consisting of steam, hydro and thermal insulation;
  • roof ventilation;
  • roofing material.

In the above photo, the entire roof structure is shown in more detail:

Rafter structure

Rafter structure

The main supporting element on which the entire multi-layer roofing cake is fixed are the rafters. The entire truss structure is being erected at the final stage of building the house box. The base and at the same time the connection with the walls of the house is the Mauerlat. The rafters are supported on it and fixed at a certain angle. In this case, the rafter structure can be for a gable roof, and then the angle of inclination is taken 20 – 30 degrees, for gable and hip roofs, the angle will be 25 – 45 degrees. But for the attic roof, two tilt angles will be used: for the lower part, 45 – 60 degrees, and for the upper part, 25 – 35. Wood is usually used as a material for the truss structure, less often metal.

Especially it is necessary to highlight the crate and counter-lattice. Since it is these two elements of the roof structure that are responsible for fastening all layers of the roofing cake, and also provide under-roof ventilation. In this case, the lathing can be ordinary and solid. Wooden planks with a section of 50×40 mm or 25×100 mm, or sheets of moisture-resistant plywood can act as a lathing. For counter-lattice, it is customary to use bars 30×50 mm. It is the presence of a counter-lattice that allows you to create a ventilation gap between the roofing material and the insulating layer of the roof..

Roof insulation

When arranging a pitched roof, special attention is paid to the creation of an insulating layer. This is due to a number of factors. Firstly, with the help of an insulating pie, the roof structure is protected from moisture. Secondly, high-quality roof insulation includes heat-insulating material, which protects the roof and internal premises from temperature extremes. Thirdly, a properly created insulating pie of a pitched roof allows you to remove excess moisture from the interior, which has a positive effect on the climate in the house and ensures the durability of the entire structure..

Roof insulation materials

The following materials are used for thermal insulation: mineral or glass wool, polystyrene, extruded polystyrene foam, polyurethane foam, foamed glass, ecowool. It is rather difficult to determine which thermal insulation material is the best from those presented. Someone prefers styrofoam, someone mineral wool. It should be chosen based on the requirements for the thermal insulation material. But the following point should be noted. When choosing, pay attention to the vapor transmission capacity of the thermal insulation. It depends on whether moisture accumulates under the roof, or it can freely go outside..

A superdiffusion membrane is used for the vapor and waterproofing layer that protects the thermal insulation. Its main advantage is one-way throughput to remove moisture without letting it back through. To protect against possible leaks, a polyethylene film, roofing material, or the same superdiffusion membrane is laid directly under the roofing material. What exactly will be stacked depends on personal preference and the allocated budget..

Pitched roof materials

Pitched roof materials

The roofing material protects the insulating cake and rafter structure from various atmospheric phenomena. There are many different roofing materials available. All of them are divided into several types: natural shingles, metal shingles, composite shingles, metal seam roofing, roofing slate, wave bituminous sheets, soft and roll roofing, asbestos-cement sheets, as well as various natural roofs. Each of these types has its own advantages and disadvantages, which should be considered when choosing a roofing material..

Requirements for materials and calculation of a pitched roof

As already noted, several groups of different materials are used to create a roof. Let us consider in more detail all the materials necessary to create a roofing pie, and also, using the example of a hip roof, we will calculate a pitched roof and all the necessary materials. It is worth noting the following: everything related to roofs, requirements and materials for them is regulated by the normative document SNiP II-26-2010. Below we will consider only the basic requirements for a pitched roof and its calculation..

Requirements for materials for pitched roof pie

Due to the fact that the roof of the house protects from various atmospheric conditions, the requirements for roofing materials are quite strict. Among all the requirements, the following must be highlighted:

  • materials must be strong and durable, capable of withstanding gusts of wind and snow pressure;
  • the roof covering must be waterproof;
  • roofing materials should not be afraid of temperature changes;
  • the roof covering must be resistant to various kinds of chemical influences;
  • low specific gravity of materials;
  • high vapor permeability;
  • fire safety and fire resistance of materials;
  • good performance of sound and noise absorption;
  • roofing materials should be easy to install and maintain;
  • environmental friendliness of materials.

The final choice of roofing depends on the angle of inclination of the rafters, as some materials have slope restrictions. The table below shows the main roofing materials and their slope angles..

Table 1.

Selection of roofing materials depending on the slope of the roof

Unfortunately, there are no materials with perfect performance. Each has its own drawbacks. But when creating a pitched roof pie, you can choose materials so that they complement each other..

Calculation of pitched roof

Calculations for a pitched roof are quite simple. It is enough to recall the school geometry course and know some of the features when calculating for different types of roofing. Consider the example of a hip (four-pitched) roof, the entire calculation algorithm.

First you need to calculate the total roof area. There are no particular difficulties here. The hip roof consists of two isosceles trapezoids and two isosceles triangles. Now, using Heron’s formula of area for a trapezoid and a triangle from the school geometry course, we calculate the total area.

Pitched roof calculation - trapezoid formulaPitched roof calculation - triangle formula

For example, for triangular slopes with sides of 3 m and a base of 4 m, the area will be 4.47 m2. For slopes in the form of a trapezoid with sides of 3 m, a base of 6 m and a top of 4 m, the area will be 14.14 m2. Now, adding the results obtained and multiplying them by 2, we get the total area of ​​the hip roof at 37.22 m2. The areas for other types of pitched roofs are calculated in a similar way. The only thing worth noting is the need for a 15 – 20% markup to the result. This is necessary for two reasons. Firstly, in the process of creating a roof, there may be unforeseen errors, and material replacement will be required. Secondly, many materials will overlap, which will hide part of their total area..

Calculation of a pitched roof made of metal tiles

But as already noted, different types of roofs have their own little tricks that must be taken into account in the calculations. So for a roof made of metal or ceramic tiles, it is necessary, in addition to the roof area, to take into account the total length of the ridge, the total length of the ridges and their number, the total length of the overhangs and their number, the total length of the valleys and their number, the total length of abutments. All this is necessary for the purchase of roofing sheets and related materials..

Calculation of a pitched roof from a soft roof

When calculating a soft roof, one should take into account the appearance of the elements of the soft roof, the method of laying the sheets, the useful and full width, overhangs and ridge floors, the size of the overlap, as well as the pattern alignment, if any..

For calculations of a sheet roof made of slate, corrugated board, copper sheets and galvanized sheets, the dimensions of the sheets, the configuration of the roof, overlaps and interlocks, overlap of ridge, overhangs, as well as all related materials for fasteners are taken into account.

With regard to insulating materials, then everything is somewhat simpler. For waterproofing and vapor control, the total roof area is used with a 20% overlap surcharge. But for thermal insulation, you will have to take several measurements of the openings between the rafters, since this is where the insulation will fit. But in the case when it is planned to make a double layer of insulation covering the rafters, it is necessary to measure the area of ​​the inner part of the roof.

Calculation of pitched roof - lathing step

Separately, it is necessary to highlight the materials for the lathing. As already noted, the lathing itself can be either solid or ordinary. For solid, either wide boards or moisture resistant plywood are used. The calculation of their number is carried out based on the total area of ​​the roof. But for an ordinary lathing and counter-lathing, everything is somewhat different. The calculation is based on the number of rows multiplied by the length of the roof. The step for it is selected based on the slope of the roof, as well as the material used for the roof. The table below shows the relationship of the pitch of the battens with respect to the slope of the roof.

As for the selection of the step of the crate, everything is quite simple. For materials such as corrugated board, ceramic tiles or slate, the step of the crate is taken such that the sheets with their edges lie on the crate.

Installation of pitched roof

The arrangement of the pitched roof is carried out in several stages: the creation of the lathing, the steam and waterproofing of the roof, the installation of heat-insulating material, the creation of the counter-lattice and the installation of the roof covering. For the most part, jobs do not require any special skills or abilities. Only the installation of roofing can require specialized knowledge and skills. The whole process of creating a roof, depending on the materials used, will require the coordinated work of two or three people. If the roofing work is performed by you for the first time, then the presence and help of a specialist will not be superfluous..

Pitched roof waterproofing

Moisture protection for a multi-layer roofing cake is of utmost importance. This is especially true of the insulating layer. Therefore, the first thing we start with the arrangement of the roof is waterproofing. All work is carried out after the installation of the rafters. The insulating material itself, namely the superdiffusion membrane, can be applied in two ways. The first – the material is laid on top of the rafters, the second – it is fixed on the inside of the rafters. It is preferable to choose the first one, since the rafters will also be protected from moisture.

Pitched roof waterproofing

When laying the superdiffusion membrane, make sure that it sags slightly between the rafters. This will protect it from damage during severe frosts, due to which the material becomes brittle and can tear from strong tension..

Super Diffusion Waterproofing Membrane

The membrane itself has a width of 1.5 m, therefore, in the process of its laying, the edges of the canvases are overlapped, and for a reliable connection they are glued with tape. In this case, the flooring is carried out along the roof, starting from the bottom. Thus, each next canvas will overlap the previous one, and moisture will simply roll off without getting inside. It is imperative to lay one canvas along the ridge to create a one-piece protection from moisture. Fastening of the membrane is carried out using an ordinary crate stuffed over.

Important! As already noted, when creating a pitched roof pie, several layers of waterproofing are laid. The above is the main one, all the others only supplement it..

Pitched roof insulation

After installing and securing the superdiffusion membrane, we proceed to the installation of the thermal insulation for the pitched roof. There are no particular difficulties in the works themselves. Depending on the insulation you choose, it fits between the rafters from the inside of the roof.

Insulation of a pitched roof with soft wadded insulation

There are several important points to note here. First, the material must fit tightly into the space between the rafters. Therefore, such heaters as mineral or glass wool are trimmed so that the mats are 5-10 mm larger. Then the material will enter tightly, will not hunch over and there will be no gaps. Secondly, if foam or extruded polystyrene foam, foamed glass was chosen, the plates are cut end-to-end. Again, so that they fit tightly, leaving no gaps. A layer of vapor barrier membrane is laid on top of the cotton wool. Fixation of the heat insulator and the membrane is carried out using the battens of the sheathing stuffed over them.

Insulation of a pitched roof with dense materials - foam

But if the cotton wool is quite soft and can easily deform, then certain difficulties can arise with hard materials. Often, when using such heat-insulating materials, small gaps remain between the rafters and the insulation itself, which are cold bridges. To eliminate this drawback, another layer of thermal insulation is laid on top of the already laid layer of thermal insulation. But this method is quite expensive. Therefore, when using insulation such as foam or EPS, a layer of thermal insulation is laid on top of the rafters..

Laying roofing

The final stage in creating a pitched roof is laying the roofing material. Depending on the material, the installation is carried out in different ways. The work itself begins with filling the counter-lattice. In this case, the following should be noted. For soft roofing materials, the counter battens are the basis and therefore will be continuous. For hard roofing materials such as slate, roof tiles or sheet metal, the counter battens are made of planks. Consider, using the example of laying bituminous tiles and slate, how roofing material for a pitched roof is laid.

Laying bitumen shingles on pitched roofs

The installation of bituminous shingles, like the installation of most soft roofing materials, is carried out as follows. Starting from the bottom of the roof, a layer of roofing material waterproofing is laid on the solid crate. The rolls are rolled along the roof and secured with special roofing nails. Then, on top of the roofing material, the tile itself is laid. All work is done from the bottom up. Tile sheets are overlapped to each other and fixed with the same nails for the roof. In this case, it is necessary to monitor compliance with the figure so that there are no distortions and empty spaces. Ridges, ridges and roof valleys are closed last, thereby creating a solid roof covering.

Laying slate on a pitched roof

The creation of a pitched roof from slate is fundamentally different from the roof of their soft materials. First of all, this concerns the counter-lattice. For it, bars are used that are stuffed over the lathing, thereby forming a gap for ventilation. In addition, a crutch is stuffed at the base of the overhang, on which the slate will rest. The very laying of slate is carried out with one or two assistants, since the sheets are quite heavy. All laying works are as follows. Having lifted up one or several sheets, they are laid out along the lower edge of the roof. Moreover, each sheet overlaps the previous one. Then they are nailed to the crate with special nails with a wide head. The next rows of slate are laid on top of the previous one with an overlap and immediately nailed to the crate. The work is quite dangerous, as it requires a certain skill and physical preparation. The ridge run, ridges and valleys are closed last. For them, use metal corner ebb or corner slate.

The work on the creation of a pitched roof can only at first glance show a simple task. But for those who have never done this, its arrangement will be a serious test. In addition, any beginner is not immune from mistakes that are not acceptable for the roof. The best way out in such a situation would be the help of professional roofers who can help with advice and deed..