Roof truss system for metal tiles. Rafter pitch for metal tiles: do the installation correctly

Metal tiles are a lightweight, durable, effective roofing material, ideal problem solver low-rise construction. Its steel endurance is perfectly combined with undeniable technological advantages. Laying large-sized sheets is done tens of times faster compared to piece-meal competitors. It lasts a long time and does not require a powerful base.

You can install the roof and build a simple frame for installation with your own hands. There will be no difficulties in your work if you know how a gable roof is structured - the rafter system for metal tiles and the installation process must take into account the technical and technological features of the coating.

Metal tiles belong to the class of rolled products. In essence, it is the old familiar sheet steel, profiled in two mutually perpendicular directions. The longitudinal and transverse waves give the sheets a similarity to the ceramic roofing prototype. The outer side is equipped with a colored polymer film that performs protective and decorative functions.

Disadvantages of the material and ways to eliminate them

The ability to imitate roofing ceramics did not rid the material of the standard disadvantages of metal. Thin sheets quickly heat up under sun rays and quickly say goodbye to heat at the slightest drop in ambient temperature. There is no insulation: heat and sound waves easily penetrate inside the steel roof and go outside unhindered. The list of disadvantages is significantly supplemented by the ability to collect condensate due to the difference in the thermal properties of the coating itself and the rafter frame elements in contact with it.

Low insulation performance and condensation are two “scourges” of a metal roof. You can get rid of them by arming yourself with information about the proper construction of a frame with a correctly laid roofing pie. If the device rafter system under metal tiles was carried out in accordance with all technological requirements; complications with laying the material and operating the structure will not arise.

To ensure that the traditional behavior of a steel roof does not bother owners and does not cause premature wear, it is necessary to correctly distribute the layers of the roofing cake. Responsibility for distribution lies with the rafter system, the list of responsibilities of which includes:

• Retention of the components of the roofing pie, which are laid on top, below and between the rafters.
• Formation of air channels that eliminate condensation, and often the possibility of its occurrence.
• Preparation of a number of supports aligned in one plane for the installation of future slopes by laying profiled sheets.

If we figuratively compare the roofing system with a living organism, then let’s say this: the “patient” will only live and function normally with a healthy supporting apparatus. In our case with a rafter frame. The method of dealing with the shortcomings of a steel coating lies precisely in choosing and strictly following an impeccably suitable installation scheme for the rafter system for the subsequent installation of metal tiles.

Types of rafter systems for metal roofing

Roofs with metal tile covering are erected over permanent and temporary residences. Gazebos, verandas, and bathhouses covered with metal “scales” look interesting. Depending on the purpose of the structure and the conditions of its operation, roofs with metal tiles are installed with or without insulation. The presence of thermal insulation is closely related to the structure of the rafter frame:

• For insulated roofs, a system is constructed that includes three insulating layers and one or two ventilation circuits.
• For cold roofs, a system with one insulating layer and one ventilation circuit is installed.

Insulated roof structures are erected if planned all year round actively use the attic. Rafter frames warm roofs calculated so that they are located in the space between the rafters. Analogs without insulation are installed on small dachas and buildings intended for temporary residence.

A roof without thermal insulation is also constructed in the case of insulation attic floor. For example, above a bathhouse or residential building with a low attic space that is clearly not intended for use, it is more reasonable to lay insulation between ceiling beams or above them.

In the construction of rafter frames, rolled metal and lumber are used for laying profiled sheets. Hardware properties are closer to coatings, but wood is more suitable for the tasks of private construction. It is easier to work with it for an independent owner who has decided to build and cover the roof with his own hands.

It’s easy to make all the frame elements yourself from lumber, assemble and connect them into a rafter system. Wood is warmer and more attractive in terms of environmental aspects.

Advantages of a gable design

The most simple option In the construction of a rafter system for laying metal tiles, a design with two slopes is rightfully recognized. Its rectangular planes are ideal for laying sheets of similar shape. The hip or one will require much more effort with diligence. Many owners are depressed by the increased consumption of large-sheet material for roofing structures with full-length and shortened hips, and are not happy with the complexity of cutting.

Manufacturers claim that the optimal design for laying metal tiles will be a design with a slope angle of 12 to 15º. Structures of lesser steepness must be equipped with a reinforced waterproofing carpet. On steeper roofs, the number of fasteners increases and the installation step decreases. In both situations, the budget for arrangement will be increased by purchasing additional insulating materials and hardware products.

Depending on the size of the metal tile and the dimensions of the structure being installed, the sheets are laid in one, two or more rows. Laying in one row is a priority, because transverse seams reduce insulation parameters and are potentially dangerous for leaks. Best length Manufacturers consider 4-4.5 m of sheets for arranging the roofs of private houses. Among the offers of most suppliers of metal tiles there is a very popular service for cutting sheets to size, which is incredibly convenient for laying on slopes with individual sizes. The length of the sheet is equal to the sum of the length of the slope and the length of the overhang, which is 0.4-0.6 m, depending on the architectural solution.

The metal tiles are mounted on the sheathing, which in turn is attached to the rafter system. The lines of all structural parts of a gable roof are strictly vertical and horizontal, which significantly facilitates the process of laying profiled sheets with similar edges. If the rafter system is built without flaws, then there will be no problems with installing the sheathing and roofing.

Construction of the rafter system

We found out that the rafter system works in tandem with the roofing pie. The layout of the rafter frame is directly related to the number of “cake” layers. Let's analyze the most complex insulated design option and find out which components we do not need to build a cold roof.

The rafter structure of a gable roof is a series of alternately installed pairs of rafter legs, design features which depend on the architectural data of the box being equipped. Manufactured and produced in accordance with the rules regulated by:

• Layered technology, requiring two specific supports for the top and bottom of each rafter leg. It is used if the building has an internal load-bearing wall or rather powerful columns are installed instead. The use of the layered method is allowed if the ridge girder racks can be installed on the floor beams with a high bearing capacity or if the ceiling is made of reinforced concrete slabs.
• Hanging technology, requiring support only for the bottom of the rafter legs. The top of the elements of the hanging rafter system rests against each other in pairs. Used if the box does not have an inner load-bearing wall and the ability to install supports under the ridge girder.

Option #1 - rafter frame for a warm roof

The use of insulation forces one to resort to technological tricks, thanks to which the layer important for the structure can retain its insulating qualities. And they will inevitably shrink when wet, because... The water that appears in the body of the material will facilitate the passage of heat waves.

Water appears in thermal insulation in three situations:

• Penetration of household fumes attacking thermal insulation from inside the structure being used.
• Formation of condensation due to the difference in temperature outside the building and in the attic.
• Leaks observed during snowmelt and heavy precipitation, resulting from non-compliance with technology and operational errors.

A properly laid roofing pie, correctly distributed and securely fixed by the rafter system, is simply required to eliminate the listed misfortunes. In addition, the duties truss structure includes the formation of ventilation channels through which air flows wash the thermal insulation and inner surface metal tiles.

Ventilation channels created by installing lathing and counter-lattice create conditions for regular ventilation and removal of condensate from the space under the roof, thereby prolonging life cycle the roof itself and the wooden parts of the rafter system.

If we imagine a conventional cut of a warm roofing pie with a rafter system from the inside of an already finished structure, then the sequence of layers and ventilation ducts will be as follows:

• Lining, plasterboard panels or similar material used for interior decoration attic space.
• Internal lathing designed to secure the vapor barrier layer to the rafters.
• Vapor barrier that prevents household fumes from penetrating into the insulation.
• Rafters between which insulation is laid. Width rafter leg should be 3-4 cm greater than the thickness of the thermal insulation. In other words, the specified gap for ventilation must remain between the upper plane formed by adjacent rafters and the outer surface of the insulation. If the thickness of the insulation is equal to the width of the rafters, i.e. The thermal insulation lies flush with the conventional plane of the slope; a lathing made of timber with a side of 30 or 40 mm is nailed to the rafter legs. This will create the required gap.
• Waterproofing, which is laid either on the rafters, if there was no need to install a counter-lattice, or on a counter-lattice. Classic polyethylene waterproofing film is prohibited from contacting the insulation so that moisture does not appear in its body. Waterproofing materials of the class of polymer diffuse membranes are allowed to lie directly on the insulation, because they are able to let excess moisture out without letting it in. Therefore, when using polymer membranes, create ventilation duct There is no need between hydro- and thermal insulation.
• External sheathing that performs three simultaneously significant functions. It is used for fastening waterproofing, to form another air gap between the waterproofing and the metal covering and serves as the basis for installing sheets of metal tiles.
• Finish coating.

As a waterproofing roofing systems bitumen varieties cannot be used under metal tiles and corrugated sheets roll materials. When heated, the insulation and roofing will release substances that destroy each other's structure.

Let's summarize. A standard roofing pie for an insulated roof has three layers and two ventilation circuits, if classic waterproofing was used in construction. There are three layers and one ventilation channel in a cake with polymer diffuse waterproofing. All components are attached to the rafter system, which must withstand the weight of the materials and the snow load. For domestic middle zone the total load is approximately 200 kg/m².

Most often, the rafter legs under metal roofs made from boards with a cross-section of 50×100 or 50×150mm, if the rafter installation pitch recommended by the material manufacturer has been followed. If the distances between the rafter legs are greater than the recommended value, the cross-section of the outer sheathing should be increased.

Option #2 - truss structure for a cold roof

Scheme roofing structure without insulation clearly confirms that there is no thermal insulation layer in it. This means that there is also no need to install all types of insulation protection from getting wet. However, waterproofing is still needed to protect the wooden rafter system in case of leaks. And ventilation between the water-repellent material and metal coatings should also be built.

A cross-section of a cold roofing cake for metal tiles looks like this:

• Rafter legs, the cross-section of which is calculated without taking into account the weight of the insulation and related components.
• A waterproofing layer laid over the rafters.
• Lathing designed to provide a ventilation gap, fix waterproofing and fasten sheets of metal tiles.

The sheathing for both types of rafter systems is laid in a special way. The step of its installation is determined by the distance between adjacent transverse steps of the metal tile sheet. Distance depends on brand roofing, on average is 300, 350 and 400mm.

The dimensions of the starting lath should be different from the subsequent ordinary bars. For example, if all ordinary laths are made of a block with a cross-section of 30x50mm, then to make the very first element from the eaves line you need to take a block of 50x50mm. The distance between the starting block and the cornice line is always less than the step between the row laths. So it is necessary that the first transverse step of the sheet lies exactly on the base.

Video instructions for installation work

The video will clearly introduce you to the process of constructing a rafter system and installing metal tiles:

The diagrams for the construction of rafter systems with insulated and cold roofing pies, disassembled “on the shelves,” represent a general guide to the actions of an independent roofer. In fact, designs are modernized and adapted to the real conditions of a particular facility. However, they may well serve as the basis for your own development.

The gable roof design for private houses is most often chosen, since it is the best option in terms of ease of installation and ease of use, strength and reliability, as well as style solutions. A gable roof is also called a gable roof and has two slopes, which can be located in relation to each other at the same or different angles, that is, the front can be an isosceles or scalene triangle. Last option can be increasingly found among new buildings, as it becomes a fashionable style solution. And, in addition to originality, such a roof has some positive features that simplify its operation.

This type of rafter system can be used for all types roofing materials, but the sheathing attached to the rafters has its own parameters for each of the coverings.

Gable roof: the rafter system for metal tiles, which has its own characteristics, must be carefully studied and calculated in advance, before purchasing materials and installing it. Let's try to understand these issues.

Types of gable roof designs

• 1 Types of designs gable roofs
• 2 The main components of a gable rafter system
• 3 Types of gable roof rafter systems
  • 3.1 Layered rafter system
  • 3.2 Hanging rafter system
• 4 How to calculate the parameters of a gable rafter system
  • 4.1 Loads on the rafter system
  • 4.2 Angle of slope of the rafter system and height of the ridge
    • 4.2.1 Ridge height calculator
  • 4.3 Length of rafter legs
    • 4.3.1 Calculator for calculating the length of the rafter leg
  • 4.4 Calculation of the pitch and cross-section of rafters
    • 4.4.1 Calculator for calculating the distributed load on the rafter leg
  • 4.5 Parameters of other lumber
• 5 Sequence of installation of the rafter system for metal tiles and roofing
  • 5.1 Video: erection of a gable truss structure under a metal tile roof

First, you need to understand what types of gable roof designs there are, since you will have to choose the most suitable one for a particular building.

• Simple equilateral gable design

This version of the gable design can be called traditional and the most used, since it is easy to install and maintain, and is also durable and reliable.

Symmetry in this system helps to achieve uniform load on the mauerlat and load-bearing walls. At making the right choice beam sections for arranging the rafter system and the Mauerlat, these parts will provide the safety margin necessary for long-term operation of the roof. Additional reliability of the structure will be provided by correctly installed racks, struts and tightening.

The disadvantage of this system for arranging rooms inside the attic space is that after installing the walls and ceiling, a large area is occupied by blind areas in the corner areas of the structure, which remain unused.

• Simple asymmetrical gable design

The asymmetrical gable design differs from the traditional system in that its slopes are located at different angles. So, one of them is usually more than 45 degrees, which allows you to increase usable area attic space, in which it is quite possible to arrange a living space, of course, with proper insulation.

Another important advantage of such a design may be a smaller slope, which is recommended to be planned on the leeward side of the building, where a large amount of snow always accumulates on the roof. A slope that is small in size but has a great steepness will not retain large snowdrifts on its surface.

The disadvantage of an asymmetrical structure is its more complex calculation to achieve uniform distribution of the load on the walls of the house.

• Broken gable structure

This gable rafter system can be called a rarity, although due to this arrangement of the slopes in attic space sufficiently formed a large room, which can be used for residential or commercial premises.

In addition to such a rafter system, a broken gable structure can also include an attic option for installing rafters.

An attic broken rafter system can provide a building with a full second floor with spacious rooms, and with enhanced insulation they can be used at any time of the year.

The main components of a gable rafter system

Now let's look at the main structural elements of the gable roof rafter system

The roof structure is one of the main enclosing elements of the building, to quality characteristics which has quite stringent requirements.

One of the most common roof sheathing materials is metal shingles, which are made from thin sheets of steel, aluminum or copper.

The elements are equipped on top polymer coating, which protects metal from aggressive external influences.

Externally, metal tiles are similar to ceramic ones, but they are more durable. This material is used for coating pitched roofs, the slope of which must be at least 14 degrees.

This is a national team frame construction roofs, consisting of many wooden or metal parts. She rests on load-bearing walls, which are a reliable basis for all overlying elements. The rafter system serves as a kind of skeleton on the basis of which the roof is made, as well as the laying of the roofing finishing layer.

Rafter system

Components rafter roof, and their main characteristics:

• Mauerlat. Timber from coniferous, which is the connecting element between the rafters and the underlying structures. It has a square cross-section with a side of 100 or 150 mm. The Mauerlat is laid along the load-bearing wall along its entire length. With the help of a Mauerlat, the loads from the roof are evenly distributed throughout the building.
• Sill. A beam having a square cross-section similar to a mauerlat. It is laid transversely to load-bearing walls, as it serves to redistribute the load from the roof racks.
• Rafter leg. From these elements, the main triangular roof structure is created, which experiences the full brunt of external atmospheric influences (rain, wind, snow, hail, etc.).
• Rack. Vertical connecting elements that distribute compressive loads from the ridge unit over the entire area of ​​the load-bearing walls. They are made from square beams, the length of the edges of which is determined by calculation.
• Puff. It is the final horizontal element of the triangle of rafter legs, preventing them from creeping away under the pressure of external loads and the roof’s own weight. Used in systems with hanging rafters.
• Struts. They perceive and redistribute bending loads from the ridge unit.
• Lathing. Consists of boards, bars or plywood sheets (in case of subsequent installation bitumen shingles), which are located at a right angle relative to the rafter legs, being an additional rigidity element.
• . The junction of two roof slopes.
• Overhang. Roofing element, protruding beyond the load-bearing wall structures at a distance of about 0.4 m. Its purpose is to limit the penetration of moisture to the walls.
• Fillies. These elements are attached to the ends of the rafters if they are not long enough to create an overhang.

Types of pitched roofs

Depending on the number of inclined planes, roofing structures can be divided into:

In private housing construction, the option most often used is gable roof, since he has a number of advantages. These include:

1. Practicality. Gable roof has a significant angle of inclination, due to which rainwater does not accumulate on its surface, but snow and wind load distributed most optimally.
2. Simplicity of device and operation. The assembly and joining of two pitched elements is much simpler than that of complex roofing structures. In addition, repairing such a roof will also be simple.
3. Aesthetics. Roof with gable construction fits seamlessly into the surrounding infrastructure.
4. Reliability(if done correctly).
5. Democratic price constituent materials.

Types of pitched roofs

Gable roof - rafter system for metal tiles

Frame made of rafters under a gable roof made of metal tiles no significant differences from structures with other covering roofing materials.

But, due to the fact that thin metal sheets have small specific gravity , the rafters will experience less constant load.

This makes it possible to reduce their value cross section, due to which you will be able to save a lot on the purchase of wooden materials.

Optimal for roofing under metal tiles The tilt angle must be at least 14 degrees.

For a roof with two pitched elements, the following are used: Frame arrangement options:

Layered rafters for metal tiles.

In this case, 2 load-bearing rafter legs are fastened together using bed(horizontally) and racks(vertical). The beam is laid parallel to the Mauerlat element, while taking on some of the force influences. The rafter system for metal tiles takes on itself bending loads only, which significantly affects the selection of the design cross section. This system can be used for buildings with large and small spans.

Types of rafters

Hanging rafters.

Unlike layered systems, this option has two rafter legs are fastened together only in the ridge knot. In this case, significant pushing forces arise on the load-bearing elements, which limits the use hanging rafters only for buildings with a span of no more than 6 m. In some cases, it is possible to install an additional connecting element - a tie, which takes on part of the thrust loads.

They can be made of wood or metal, and can also be installed at the bottom (acting as a load-bearing beam) or at the top of a triangular structure. It is worth considering that the higher the tightening is located, the greater the force it will absorb.

NOTE!

To provide quality work tightening must be taken care of about the reliability of fastening with load-bearing rafter legs.

Combined option

Used to create an original roofing structure. Includes elements of both hanging and layered systems.

How to calculate the angle of rafters?

To implement a gable roof you need to know a few geometric values ​​of the building, namely:

• Half span width - L;
• The distance from the load-bearing wall to the roof ridge (or the height of the support post) – H.

Standard formula: α = arctan(L/H)

Where α is the desired roof inclination angle.

Knowing this value, you can calculate the length of the load-bearing rafter leg:

l = H/sinα.

Where l is the length of the rafter element.

Rafter angle

How to calculate the load?

To implement correct selection roof frame parts required calculate temporary and permanent load values, acting on its structural elements.

The constant load includes the weight of all elements, as well as the mass of the load-bearing elements themselves and the sheathing.

Temporary loading options include force effects from wind, snow cover, rain masses, as well as the weight of a person (to take into account options for subsequent repairs).

Dead load calculation

Weight of the roofing pie.

It is determined by adding the masses of all its elements, namely steam, hydro and thermal insulation, as well as metal roofing. In this case, the weight of one linear meter (can be found in the regulatory documentation) is multiplied by the value of its length.

Weight of the rafter system.

Determined by adding the weight values ​​of the sheathing, rough flooring, and supporting frame. The mass of each element is calculated by the formula:

M = V * p,

Where V is the volume of the element, calculated depending on geometric characteristics cross-section and length elements;

P – Density of wood used (depending on the species).

Total constant load = weight of the rafter system + weight of the roofing pie.

Live Load Calculation

Conducted in accordance with regulatory documentation (SNiP 2.01.07-85 “Loads and impacts” or Eurocode “Actions on structures” part 1-4).

To determine the value of wind exposure, the roof structure is conventionally divided by height into several parts. For each of them, the wind load value is calculated. To obtain the total wind pressure they must be summed.

Formula for calculation:

Wm=Wo×k×c,

Where Wm is the value of the wind load;

Wo – normative meaning wind pressure determined from zoning maps;

k – wind pressure coefficient (determined depending on the height according to regulatory documentation);

c – aerodynamic coefficient (for a gable roof – 0.8).

Determined by the formula:

S = µ×So;

Where So is the standard value of the snow load, determined from the zoning map.

µ is a coefficient that is determined depending on the angle of inclination of the roof:

• For α≤30 deg. — µ=1
• For α≥60 deg. — µ=0
• For 30≤α≤60 deg. — µ=0.033×(60-α)

Snow load areas

How to choose timber and calculate the pitch of rafters for metal tiles?

Determining the cross-sectional value of the beam of the rafter element is carried out in several stages.

Calculation of the load distributed on each linear meter designs:

Qр = L×Q;

L – Rafter pitch.

The L value is calculated as follows:

The length of the roof slope is divided by the expected pitch of the structures (for convenience, it is most often taken equal to 1). Then 1 is added to the resulting value. The resulting value reflects the number of rafters that need to be installed on one pitched roof surface. On last stage the value of the axial distance between rafter elements, by dividing the length of the roof slope by the number of rafters.

The distance between the rafters for metal tiles is a standard step of 0.6-0.95 m.

Rafter pitch

Then we determine the maximum working area of ​​the rafter leg (Lmax). Let's move on to calculating the cross section. To do this, we find its height using the formula:

H ≥ 8.6*lmax * sqrt(Qp/(b*r)), with roof slope α<30 град;

H ≥ 9.5*lmax * sqrt(Qp/(b*r)), with roof slope α≥30 degrees;

Where b is the width of the cross section,

r – the value of the standard resistance of wood to bending loads (determined according to regulatory documentation depending on the type of wood).

To simplify calculations, you need to use the standardization table for rafter elements (GOST 24454-80 “Softwood lumber. Dimensions").

If the inequality is not met, it is necessary to increase the value of the geometric characteristics of the section and repeat the calculation.

What is the difference between the rafter system for cold and warm roofs?

The main difference between these two roofs is the system of supporting the rafter elements. In the case of a warm attic, the main supporting element is the mauerlat, as well as the supporting beam system. In a cold roof, rafters are installed directly onto load-bearing walls.

Installation of rafters under metal tiles

All roofing installation work is carried out at a fairly high altitude. To minimize the risk of falls and make working at heights much easier, you can assemble the frame of the supporting rafter system on the ground.

To do this, you need to create a template from the boards, according to which further assembly will be carried out.

It is produced in several stages:

• The boards are lifted above the walls of the building, leveled, and then are fastened using a nail.
• Level the angle of the boards in accordance with the project, by lowering and raising them. The elements are fixed.
• The result should be a structure resembling the shape of the future rafter system, made in accordance with the calculated geometric dimensions of the roof.
• The template is lowered to the ground, according to which the finishing elements are fixed together. More details in the video below.

Then you should take care of installing the supporting element - the Mauerlat. As mentioned earlier, it is laid on load-bearing walls in the longitudinal direction. Fastening is done using studs (on an armored belt or masonry) or using wire rod (for buildings with a small roof height).

CAREFULLY!

When using a pin connection, the connecting elements no need to wall up tightly into the wall. They should protrude from the wall by 30-40 mm, since the nut will be screwed onto the studs.

The next step is to create ridge girder, serving as a supporting part for the entire structure of the gable roof. It is made from timber or hewn logs. If the span of the building is no more than 6 m, it can be supported without additional supporting elements. Otherwise, construction trusses must be used for installation.

Installation. Part 1

After installing these elements, you can lift and install the main rafter element assembled according to the template. Fastening to the Mauerlat can be done in 2 ways:

Rigid connection. This is done using corners and beams. Less commonly used are fastenings by sawing on rafter legs, followed by fixation with nails or staples.

Features: in addition to the main connection, it is necessary to tie the rafters to the wall using anchors or a wire structure.

Sliding. It is based on the creation of a hinged connection. It is made by joining elements using cuts. The elements are connected by a metal embedded part with holes for bolts, or 2 nails, which must be driven in at an angle.

Wooden trusses must be installed in a certain sequence. First, the outer trusses located at the ends of the building are installed. Then a cord or rope is stretched between them, with the help of which the verticality of their installation is checked. Next, under the cord, further installation of rafter structures is carried out in accordance with the specified design step.

Installation. Part 2

Creating a roof from metal tiles is a rather labor-intensive process that requires certain skills and a trained hand. Therefore, to carry out proper installation, you must at least work under the supervision of a competent specialist.

Useful video

Video instructions for self-installation of rafter legs:

Each of the individual developers knows that the roof of any house is one of its most important structural elements. The roof protects the building from the effects of various adverse atmospheric phenomena, such as snow, rain, scorching sun rays, and also helps to retain heat in the home. Therefore, in order for the roof to effectively cope with the functions assigned to it, it must have adequate reliability and high strength.
As you know, the basis of any durable roof is its frame or rafter system. The reliability and strength of the roof, as well as the service life of the entire building, depend on how competently the rafter system of the building is designed and subsequently correctly assembled.
It is worth recalling once again that the reliability of the roofing structure depends on the thoroughness of the preliminary calculations, or more precisely, on the correct choice of the pitch between the rafters of the roof, which will subsequently be covered with metal tiles.
If, during preliminary calculations, the loads acting on the roof are incorrectly determined, or the parameters of the rafters are incorrectly assessed, during subsequent operation the roof may become deformed or even completely destroyed.
When calculating the design of the rafter system, it is necessary to correctly calculate the distance between the rafters. This part of the calculation does not present any particular difficulty if standard calculation methods used by specialists are used for this purpose.
The design features of the rafter system depend on the type of roofing (in our case, metal tiles), as well as on the loads acting on the roof. These loads can be either temporary or permanent.

The category of temporary loads includes the following impacts:

• pressure created by wind flows;
• the mass of snow lying on the roof;
• the mass of moisture falling in the form of rain;
• loads arising during the performance of certain repair work.

The category of permanent loads includes the following factors:

• weight of the roof covering;
• a lot of materials intended for roof insulation;
• mass of finishing and facing materials (if there is an attic);
• weight of the sheathing and rafter structure.

When designing a frame structure, first of all, you need to decide on its type, which directly depends on the method of installing the rafters. Rafters can be inclined, hanging or combined. The number of rafters to be designed, their cross-section and the distance between them are chosen depending on the type of attic. The attic can be either attic or non-residential.
To manufacture the structure of the rafter system, coniferous wood with a moisture content of no more than 20% is used. The wood chosen for rafters should not have blue stains or rot. The lumber selected for manufacturing is carefully treated with fire retardants and antiseptics.

Preparatory stage

Creating a roof for any building begins with choosing the type and material used as a roofing covering. Currently, most individual developers choose metal tiles as roofing for their homes. A roof created using this material is strong, durable, highly attractive in appearance, the material itself is not expensive and is easy to install. At the same time, metal tiles are much lighter than their counterparts - ceramic tiles.
Externally, a roof created using metal tiles has the same attractive appearance as a roof using clay tiles. However, if we compare metal and clay tiles, it is necessary to note the advantages that metal tiles have in comparison with their clay counterpart:

• metal sheet tiles are a more technologically advanced material, as a result of which the creation of a roofing covering does not take much time and other resources;
• metal tiles have less weight than their clay counterparts, the numerical value of which can be determined from the ratio: (weight of 1 m² of clay tiles) – (weight of 1 m² of metal tiles) = 35 kg.

Calculation of the number of rafters and the step of their installation

Table depending on the length of the rafters on the pitch between them and the cross-section of the timber used

To calculate the required number of rafters, you need to perform the following operations sequentially:

1. Measure the length of the roof slope. Then divide the resulting value by the step length between adjacent rafters.
2. Add one to the value obtained in the calculations under point No. 1. Round the resulting value to the nearest whole number. Using a similar method, calculate the number of rafter legs for the roof slope.
3. Next, the length of the slope should be divided by the numerical value of the number of rafters, and then the axes of their installation should be determined.
4. The pitch of the rafters is directly dependent on the type of roofing, as well as on the angle of inclination of the roof slope.

For example. The length of the slope is 18 meters. The step size between the rafters is 0.8 m. Therefore, 18/0.8+1=23.5≈24. So, to create a roof frame you will need 24 rafters.

Installation of rafters

It should be noted that rafter systems created for various types of roofing have minor differences. The difference depends on the size of the sheets of material used, as well as their own weight. To create the design of the rafter system, you will need to prepare the following materials and tools:

• hacksaw for working with wood;
• chainsaw;
• chisel;
• carpenter's axe;
• construction stapler;
• plumb line and building level;
• screwdriver;
• electric drill;
• hammer;
• self-tapping screws;
• nails;
• metal elements intended for fastening rafters;
• board 50x150 mm, intended for rafters;
• timber 150x150 mm, used to create a Mauerlat;
• board 25x100 mm, intended for the construction of sheathing;
• timber 30x50 mm, used during the construction of the counter-lattice.

After all the required calculations have been completed and the appropriate tools and materials have been prepared, you can begin assembling the structure of the rafter system, on which the metal tiles will subsequently be laid.

The procedure for constructing the rafter system structure:

1. First of all, it is necessary to install a mauerlat from timber of the appropriate cross-section. The Mauerlat is the base of the roof structure, which takes on the load from the rafter legs. The timber selected for this purpose must be laid along the perimeter of the walls, within the pre-prepared reinforcement belt, and then secured with anchor bolts. A layer of waterproofing in the form of a strip of roofing material of the required size must be laid under the timber.
2. On a horizontal, flat surface, in accordance with the data from previously prepared sketches, it is necessary to create a template using flat boards. The template is used for the subsequent production of roof trusses. In the ridge they must be secured with nails or metal plates.
3. In the timber from which the Mauerlat was previously made, at pre-calculated distances, recesses of the appropriate size are made, intended for the subsequent installation of rafter legs.
4. The previously made trusses are lifted onto the roof and installed on the timber. In this case, it is necessary to attach the outer blocks first. The verticality of their installation must be checked using a plumb line.
5. Next, a cord should be pulled between the two outer trusses along which the remaining elements will be installed. The rafter legs must be attached to the Mauerlat beam using self-tapping screws and metal corners.
6. Horizontal wooden lintels should be installed at the top of the trusses.
7. In the lower area of ​​the rafter legs, it is necessary to install a cornice overhang, the projection of which from the vertical plane of the house wall must be at least 50 cm. For this purpose, a board or beam of the appropriate size should be installed in the appropriate place on the wall, at the level of the ends of the lower part of the rafters. The end of the rafter leg must be secured on one side with a short board, which is called a “filly,” and on the other side it must be attached to the wall.

Processing of structural elements of the rafter system

During its subsequent operation, the roof truss system will be exposed to a number of unfavorable factors, therefore, during its construction, it is necessary to ensure that the wooden parts of the structure are impregnated, thus creating the following types of protection:

Preparing the frame for laying the roof

For subsequent installation of metal tiles, the rafter structure must be prepared. To this end, the following activities should be performed in the specified order:

1. On the surface of the wooden rafters, on which the metal tiles will subsequently be laid, it is necessary to unroll a special film designed to protect against moisture and secure it to the bars of the structure using a stapler. During installation of the film, it is necessary to ensure an overlap between adjacent strips of at least 150 mm; the joints between adjacent strips must be taped with adhesive tape. The sag of the film should be about 20 mm.
2. It is necessary to install a counter-lattice on top of the installed waterproofing film. For this purpose, wooden blocks with a cross section of 30x50 mm are used. The counter-lattice will provide the roof with the necessary ventilation gap.
3. Next, boards with a section of 100x25 mm must be secured to the mounted counter-lattice. At the same time, they must be laid so that the first board from the bottom is twice as thick as the next boards. The pitch of the sheathing should be in the range of 350 - 450 mm.
4. The roof drainage system fittings should be installed on the frame prepared in this way.
5. Upon completion of the work described above, the roof rafter system can be considered fully prepared for the subsequent installation of metal tiles.

In the vast majority of cases, when repairing a roof, the choice falls on metal tiles.

In addition to the long list of economic and operational advantages, this material is also interesting for its suitability for self-installation.

In this case, even the basic skills of a home craftsman will be enough to ensure that the roof is not only durable and practical, but also attractive in appearance.

Advantages of metal tiles

The widespread use of metal tiles is due to the combination of the following advantages in this type of roofing material:

• Economic expediency.
  Compared to most other roofing coverings, metal tiles have a relatively low cost.
  What makes purchasing such a roof even more profitable is the ability to avoid hiring builders to install it, as well as its long service life.
• Light weight.
  With an average weight of 1 sq. m of material is about 6 kg, the total mass of the roof is relatively small. This allows you to do without the use of a powerful and expensive rafter system. In addition, a lightweight roof does not require the installation of continuous sheathing, which simplifies the calculation of the roof and reduces the cost of work.
• Resistance against external factors. Protection is provided by the use of several security words in the design of the roofing sheet. Therefore, the metal base of the canvas is not afraid of prolonged exposure to moisture, direct sunlight, or damage during installation or hail.
• Aesthetics. The production technology of metal tiles allows you to create absolutely any texture. Accordingly, on the market you can easily choose an option suitable for the overall exterior of the building. The range is further expanded by the possibility of painting sheets in all shades of the palette.
• Fire safety. The basis of the metal tile is a sheet of galvanized steel. This material is completely non-flammable, making it absolutely fireproof.

The indicated advantages of metal roofing make it the most practical, affordable and attractive externally a roofing option.

Materials and tools

To install metal tile sheets, you will need a set of traditional tools for finishing work:

• electric screwdriver;
• jigsaw or circular saw;
• marker;
• construction stapler with staples;
• metal scissors;
• scotch;
• laser plane builder or building level;
• roulette.

Important! To cut sheets of metal tiles, you cannot use grinders with abrasive discs operating at high speeds. Their use will lead to overheating of the steel base, melting and destruction of the polymer protective coating. Such damage greatly reduces the service life of the roof.

Of the materials, in addition to the metal tile itself and its accessories, you will need the following:

• bars 50 x 50 mm;
• boards 100 wide and 25–35 mm thick;
• sheet waterproofing material;
• wooden slats;
• galvanized screws, nails.

You will also need personal protective equipment and auxiliary equipment: a ladder, scaffolding, a brush for sweeping away debris, etc.

Find out more about laying corrugated sheets on a gable roof:

Structure of the roofing “pie”

The basis for creating a roof made of metal tiles is rafter system. In a gable (or gable, as it is more often called in everyday life) roof, the rafter system has the most convenient configuration for installation work, since it forms only two planes.

A layer of waterproofing material (3) is laid on top of the rafter system. Without it, moisture condensing on a metal roofing sheet will be absorbed into the wooden structures under the roof, destroying them. Waterproofing also helps in cases where the roof begins to leak.

Vertical slats - counter-lattice (4) - are attached to the waterproofing material along the rafters. Their purpose is to organize a ventilated space between the waterproofing and the sheathing.

In addition, the roof structure contains frontal boards (8) and eaves strips (10). The first ones are stuffed onto the end part of the rafters (1) and protect from moisture falling with the wind. The latter serve to remove moisture flowing down the waterproofing layer.

Installation procedure

On gable roofs metal tiles are laid first on one slope, and then on the other.

Laying sheets of metal tiles should begin with lower slope angle.

All installation work on roofing is carried out in several stages:

Checking the geometry of load-bearing roof elements

At this stage, the diagonals of the roof slopes are measured and compared using a tape measure. If they coincide, then the roof has a rectangular shape suitable for laying metal tiles.

In addition, you need to use a level or builder to make sure that the ridge and both cornices are strictly horizontal. The flatness of the slopes must also be checked. Emergency sections of the rafter system are being repaired.

Installation of the frontal board and filing of the roof overhang

The place where the front board is attached (8) is the end (bottom) part of the rafters (1). This roofing element is fixed with galvanized nails.

Front boards should not completely isolate the under-roof space from the street. To ensure free passage of air, ventilation gaps must remain between them.

A horizontal sheathing is installed on the reverse side of the front board under the roof overhang. As such, you can use perforated plastic panels. This option is convenient because it allows you to use fastening j-straps for plastic, nailed to the front board from behind. If boards are used, ventilation slots should be left between them.

Installation of gutter hooks

Hooks(9) should be placed in a straight line with a slope towards the planned drainage. Reliable drainage will be ensured by the slope angle from 5 mm per meter of gutter.


The most practical and easy to install are hooks of extended length. They are sewn to the bottom of the rafters on top of the front board. To ensure the vertical position of the hook, grooves of the required depth are cut in the board and the bottom of the rafters.

First of all, the upper part of the hook is nailed or screwed to the top of the rafters. Then it is bent to the required position and fixed on the end of the rafters. If the drainage system is installed after laying the metal tiles, then short hooks are used, the upper part of which does not go under the roofing.

Laying waterproofing material

Rolled water-repellent materials (films) are used for the roofing “pie”. As it moves onto the rafters, the roll unfolds horizontally along the eaves. You should start from the bottom of the roof. Each subsequent strip is laid with an overlap on the bottom one. The amount of overlap is 15 cm.

The waterproofing sheets (3) should be fixed with a construction stapler. The material is allowed to sag up to 2 cm. The joints are taped with tape. The top and bottom of the film are determined by the factory markers applied to it.

Along the rafters on top of the waterproofing they are stuffed vertical(4) and horizontal(6) laths made of wooden strips. They are nailed along the central part of the rafter beams.

Attention! Metal roofing and bitumen waterproofing are incompatible materials. When the roof heats up under the sun, the bitumen will melt and the canvas will lose its ability to repel moisture.

Find out how to make a gable roof gable with your own hands:

Installation of sheathing

The bars or boards of the horizontal sheathing begin to be packed from below, from the eaves. The first beam of the sheathing must have a cross-section larger than the cross-section of the remaining beams. When installing it, it is necessary to control strict parallelism to the cornice. Installation of metal tile sheets begins with fixation on the lower beam of the sheathing. Therefore, the appearance of the entire roof will largely depend on the accuracy of its installation.

The pitch of the sheathing beams depends on the distance between the horizontal waves on the metal tile sheet and must coincide with it. Most often the pitch is 300, 350 or 400 mm. The only exception is the step up to the second beam of the sheathing. Here it should be reduced by 70 mm.


The topmost beams of the sheathing are also stuffed with decrease step, right up to nailing the beams tightly. This will facilitate the installation of ridge elements and add strength the entire structure. Around roof and dormer windows, chimneys, ventilation ducts and other additional elements(bridges, snow guards, etc.) the sheathing should also be strengthened by stuffing a continuous web of beams.

Installation of curtain rods

The planks are attached along the entire cornice using galvanized self-tapping screws. The fastening pitch is 300 mm. If the length of one bar is not enough, then it is increased. In this case, the planks are laid overlapping with overlaps of 50–100 mm.

The eaves strip is attached with a slight tension, then the roofing material will be more resistant to gusts of wind and less noisy.

Installation of the lower valley

Where the roof planes (for example, the slope of the roof of a house and the slope of the roof of a dormer window) form intersections at a slight angle, the installation of a special strip is required - the lower valley (20b).

A continuous plank sheathing (7) is placed under it. Boards with a cross section of 150 x 25 mm are applied as lathing material.

Under the lower valley you will need a continuous strip of sheathing about 300 mm wide.

The position of the lower valley is selected so that its edge in the overhang area passes over the cornice board. The sheet of metal tiles and the lower valley strip are not directly fastened together, but are laid with porous insulation.

Installing a chimney outlet bypass

For a brick pipe, the procedure will be as follows:

• A layer of waterproofing is applied around the perimeter with an overlap of 50 mm on the pipe. For fixation, you can use heat-resistant tape;
• bypass strips (28) are installed;
• A groove about 15 mm deep is cut along the pipe, into which the upper edges of the bypass strip are inserted. You can only tap on solid bricks; it is prohibited to do this on masonry joints;
• The drainage bar organizes the drainage of water, which either drains into the nearest valley or is directed to the eaves.

The decorative pipe surround is not installed at this stage of the work; metal tiles are laid first. For round chimneys, the lining is made of sealing tape. To ensure a tight fit to the pipe, the tape will need to be cut along the top edge in several places before gluing.

Installation of metal tile sheets

If it is possible to lay sheets along the entire roof slope in one row, the installation order will be as follows:

• the outermost sheet is applied and its position is verified relative to the eaves and side section of the roof;
• the first sheet is fixed in the upper part with one self-tapping screw;
• the next sheet is laid with an overlap in the wave and aligned vertically;
• the sheets are sewn together with self-tapping screws, but the threads should not be screwed into the beams;
• the following sheets are mounted in the same way;
• the resulting assembly is once again verified relative to the ridge and cornice;
• screws are screwed into the sheathing.

If the height of the sheet is less than the length of the slope and you have to lay the metal tiles in several rows, the procedure will be as follows:

• the first two sheets are laid according to the same pattern as for single-row installation;
• the third sheet is placed on top of the first with a horizontal offset of 150 mm, after which these two sheets are fastened together;
• the next sheet is placed above the second and attached to it horizontally. With the third sheet, fastening is carried out on the vertical side;
• four fastened sheets are aligned together and fixed to the sheathing by tightening the screws.

At the final stage fixation produced at the bottom of each wave by bottom cut sheets. In places where vertical overlap, screws are screwed into crest waves. Distance between self-tapping screws should be chosen with this calculation: there should be 6–8 pieces per square meter.

For detailed instructions on installing metal roofing, see this video:

Dormer window device (“cuckoo”)

The location of the "cuckoo" is determined early. When laying sheets of metal tiles, areas corresponding to configurations dormer window.

Roofing pie under the window neatly sawed out. By perimeter windows are being installed additional sheathing beams.

Gaps between the timber and the sheet of metal tiles are sealed. To drain water, install valleys the top and bottom of the dormer window.

Installing the end strip

The purpose of this slats(29) – protection from precipitation and sharp gusts of wind penetrating under the metal tiles. In addition, the end strip also performs decorative function: when installed correctly, its upper edge overlaps crest waves of metal tiles. Screw The end strip starts from the side of the cornice. If it is necessary to build up, provide an overlap in 100 mm.

Installation of the upper valley

The purpose of this element is to drain water, in addition, upper valley(20a) makes roof joints more aesthetically pleasing.

For installation, use self-tapping screws, screwing them in so that don't disturb waterproofing layer. Between the upper valley panel and the surface of the metal tile, a self-expanding insulation.

Installation of junction strips

These planks allow you to organize careful And sealed transition from the roof surface to adjacent walls and other structural elements of the building and roof.

The connection to the wall is arranged according to the same principle as the connection to the chimney.

Installation of ridge strips and external corners

Before installation ridge strip you should make sure that the gap between the waterproofing sheets of adjacent roof slopes is not less than 20 cm. On top of the top continuous sheathing you can lay additional a layer of waterproofing material in a strip of 150 mm.

Fastening is carried out with self-tapping screws screwed into sheathing through the covering wave. To increase the ridge strip, organized overlaps, serving as additional ribs rigidity.

End parts of the ridge are closed with external corners fixed with self-tapping screws. Between the metal tile and the ridge strip is laid insulation made of elastic material.

Installation of stairs, walkway, roof railing and snow guard

Roofing accessories made of metal tiles are mounted on top of the roofing.

Their places placement are determined in advance and are intensifying additional beams and sheathing boards.

Particular attention is paid to installation snow guard(21). It is fixed to the rafters complete reinforced screws.

Installation of a drainage system

When installing water drainage systems The following rules should be followed from the roof:

• to one drain pipe it is forbidden install more than 10 meters of drainage gutter;
• Part gutters above the funnel should be cut at an angle with sides in 100–110 mm;
• funnel should be located under the gutter at a distance of 150 mm.

All elements of the drainage system, including plugs, funnels, etc., have a fixation system among themselves. However, after installation work is completed, they should be further processed. silicone sealant.

Attention! Drainpipes are installed with the crimp down, otherwise leaks cannot be avoided.

Roof grounding with a separate bus

Since metal tiles have the ability to conduct electricity, then for safety reasons it should be provided with a system grounding.

Grounding is done by connecting electrical wires large section with one end to the roof (through a self-tapping screw). The second end is securely attached to metal structure buried in the ground depth at least a meter.

Post-installation processing

Metal tiles require periodic inspection(semiannually). From the roof and drainage system clean up debris and leaves, and the surface cleanse with a soft brush.
The canvas in problem areas can be tint, this will increase its corrosion resistance.

Installing counter battens under the rafters

The system of counter-battens under the rafters allows you to insulation roofs. They are used as counter rails wooden beams or planks nailed.
Further into the space between rafters a layer of insulating material is placed behind the counter-trikes, which additionally reduces noise metal roofing.

Laying vapor barrier and fastening with slats

Leave insulation open is unacceptable, since moisture can get on it and negate the entire insulating effect. To prevent this, apply to the insulation vapor barrier film(16). This material does not allow moisture to pass through, but effectively allows water vapor to pass through, leaving the insulation dry

Wooden slats are placed on top of the vapor barrier for fixing whole pie.

Safety precautions

Work on installing the roof of gable roofs refers to work with high level of danger, and the more slope stingrays, the stricter the safety requirements. Don't neglect them, take care of yours health:

• be sure to wear safety belt, tied with a strong rope to a strong part of the building;
• work in shoes that have good clutch with surface;
• stairs And forests securely fasten to the walls of the house;
• roof protect scaffolding, scaffolding, mesh or sides with a height of at least 1 m.

When working with metal tiles the following rules should be adhered to:

• always use mittens;
• to not allow applying excessive force to metal;
• take into account the strength of the wind and windage sheets of metal tiles.

In addition, it will not be superfluous to use all available devices that make work easier. Eg, inclined guides from long boards will not only increase safety when rise sheets, but will also ensure the safety of the material.

In general, installation of metal tiles on gable roof does not pose a serious problem. It is enough to follow safety rules and follow all recommendations to get reliable And beautiful roofing at the lowest possible cost.

The following describes the safety rules that must be followed when working with metal tiles: video: