The roof of any structure has one main function, and this is to protect the house from precipitation. This is its main purpose, except that it gives the building a certain style. Based on this, all calculations of this important structure are made. Of all the existing designs of modern layouts, the most popular are gable and multi-slope structures, if an attic house of a complex system is being built. In any case, the roof project is done according to typical rules, the main of which are determining the load on the house and the load on the rafter frame. The width, height, and angle of inclination of the slopes will depend on this.
Varieties of roofs
According to their use, houses are attic and non-attic. There are two types of construction. It is pitched and flat. But let's talk about everything in order. In modern construction, the question is very rarely asked how to make a flat roof. It's irrelevant todayas flat roofs are rarely used. The only drawback of a flat design is the small angle of inclination for rainwater drainage. They often leak and require constant maintenance and repair. Many houses with flat systems are converted to pitched houses, which have many advantages. These structures are easy to operate and do not require frequent repairs. They have a very wide variety. This is single-pitched, and double-pitched, and hip, and half-hip, tent and multi-gable, broken, conical and domed roofs. There are also combined ones in this list, in which several types are combined.
To have at least some idea about the types of roofs, you need to give a brief description of each:
- The name "gable" itself gives a reasonable explanation that in this design there are only two slopes.
- More complex in design is the hip and semi-hip roof, which already has four slopes. This configuration is used in the construction of attic rooms. The difference between them is that the first ones have side slopes in the form of full-width triangles, while the half-hip ones have only small sloped triangles that cover the gable walls.
- Shed roofs in housing construction are used only in small structures: it is relevant for garages, small country houses and other small structures.
- And the list of structures continues with a roof in the form of a tent with four slopes that converge at one point in the ridge part.
- And finally broken linespitched have a complex design. Only it, as it were, consists of two planes with one angle of inclination, and the other two - with another. The lower slopes are a continuation of the two upper ones. They are connected at the level of the attic floor. The lower slope continues the upper one, but only at a different angle.
Roof project
First of all, you need to pay attention to the climatic conditions and the loads that will act on the truss system, on the box of the house and on the foundation. Typically, design documentation is developed by design firms. How to make a roof in this case? The developer's task is only to convey to the designer his desires in choosing the configuration and provide him with geodetic, geological and climatic studies of the area on which the building will stand. The project gives the exact dimensions and design plan. All loads are determined and recommendations are given in the choice of materials for the house, and for the roof, and for roof insulation.
Also, the projects indicate all nodal connections and fastenings in the truss frame. Here are all its dimensions and the installation locations of the transverse and longitudinal beams. But, as usual, experienced craftsmen do not always refer to project documentation and do everything from their own considerations and experience. Therefore, to check the experience of the masters, they need to show the project documentation for reading it. Not all masters can read projects. This is how developers need to act on all issues, how to make a roof, so as not to fall into the trap of inexperienced craftsmen, so that later they do not have to repairyour home.
Configuration and dimensions
Roofing material is important, much depends on its weight and resistance to the elements, wind, frost, precipitation. The first parameter is the width, which is determined only by the dimensions of the house. This is determined by the architectural plan. And further parameters will be directly related to the width and climatic conditions.
The height and slope of the slopes - these indicators are interconnected and related to climatic conditions. If a house is being built in areas with high rainfall, then, accordingly, the question of how to make a roof with the desired slope and height will come first in order to provide the most effective protection from rain and snow. The height is calculated from the width and steepness.
It is clear that it is important to respect the proportions between the height, width and steepness of the ramps. Roofing material is selected from the slope and height, which is selected not only according to the configuration, but, above all, in relation to climatic conditions: precipitation, wind, frost and snow. Indeed, the lion's share of the loads of these elements falls on the roofing material. In his choice plays a role and weight, and resistance, and flexibility, and resistance to temperature extremes. This also applies to the wooden roof.
Layer system
The second step in determining the configuration will be the choice of the type of frame. For a gable design, there are two types: layered and hanging. The difference is small, but it is of great importance when calculating the loads on the house and on the truss system itself. Let's take the firstconstruction. This method involves a more secure fastening of the rafters. With such a system, the legs of the rafters lie on the longitudinal beams, the first of which lies on the strapping base, on the Mauerlat. The leg of the rafter rests on it and is connected by several fasteners. In the middle of the frame system, side runs are installed, against which the rafters lean. From this, the system is called layered. The third beam is a ridge beam, on which the rafters rest with their ends. At all docking nodes, they are reinforced with metal fasteners, corners, screws or nails.
Hanging design
There is no truss beam structure in this frame. The rafters are installed with their paw on the Mauerlat, and the ends are connected in the ridge part. It seems that they are hanging over the box at home, leaning on the beam only with their paws. Such a rafter roof system has a large tensile load on the rafter triangle. To fix it, the rafter leg is fastened with transverse beams, supports and slopes. This system is used for small houses. It cannot be said that it is less effective. Each configuration has its own advantages and disadvantages. To reinforce the fastening of the hanging rafter structure, transverse beams are used to connect the rafter legs at the base.
Roof width. Calculation
In the cornice part, the size is determined by summing the width of the house box and two cornice overhangs. Cornice overhangs may have differentsizes:
- So, for metal tiles, eaves overhangs are made within 40-50 cm.
- For slate, the value of the cornice overhang is 10 cm.
- Bitumen shingles - 30-40 cm.
- Profiling - 50 cm.
- Ceramic tiles - 50-60 cm.
If, for example, the width of the box becomes 4 m, then, accordingly, the width in the cornice part will be up to five meters when using metal tiles, the cornice overhangs of which are 40-50 cm. The calculation of the width in the cornice part is done due to the need for more reliable protecting the walls of the house from slanting rains. Therefore, an increase in the eaves width occurs due to the lengthening of the transverse logs of the strapping beam or brickwork.
Slope slope. How to make a payment
The angle of inclination of a pitched roof, including a pitched roof, depends on three factors:
- The first is the roofing material and the weight of the roof, along with the roofing cake.
- The second influence on the steepness of slopes is climatic conditions. In areas with abundant rain and snowfall, the degree of inclination will increase.
- The third indicator of the steepness of the slopes is the total weight of the truss system. And yet, the indicator depends on the number of joints of roofing sheets.
The more joints, the steeper the plane should be. The quality of the roofing material also has something to do with the slope. The harder the material, the more allowance is given for lowering the degree of inclination. Has an effect on the steepness and weight of the material. The heavier the roofing sheets, the moresteepness. The tilt angle is adjustable from 10 to 60 degrees.
The calculation of the angle of the roof, that is, the slope of the slope, is carried out according to the following formula:
- Tg (A)=h/c;
- Tg (A) - tangent of the angle;
- h - half the span of the house;
- c - the height of the rafter system, that is, the roof from the base to the ridge.
Take approximate dimensions. If the span of the house is 12 m, then half of it is 6 m. The height of the truss system is 3 m. We substitute these dimensions into the formula and get:
Tg (A)=3: 6=0, 5.
We got the tangent of the angle 3/6 or 1/2 (or 0, 5). We recall the geometry and, using the table of tangents, calculate how many degrees the tangent of the angle 0.5 has. In our example, it becomes 27 degrees.
Skate height. How to calculate
This parameter also has a certain dependence on the width, steepness and weight of the roofing system. The heavier the roof, the steeper the slopes should be. The steepness of the slopes also affects the height. In fact, in terms of fire safety, the top cannot be lower than 1.6 m. If the steepness is large, then the height will increase. In this case, in order to reduce the height while maintaining the steepness, a broken or cut structure is made. In the ridge part, it may have a flat end. Accordingly, a broken truss frame is also created under the broken system. In the upper part, the base of the sub-rafter system is constructed, on which the rafter legs lie. It is necessary to make a frame of a layered structure. Skate height is calculatedbehind the formula:
- H=L x A.
- H - the height of the skate.
- L - leg of a triangular truss.
- A is the tangent of the truss triangle.
Take, for example, the width of the house is 6 m. Divide the width of the house by 2 and get the leg of a triangular truss. In our example, the leg is equal to L=3. From the tables we write out the tangent of 40 degrees - 0.84.
Substitute the numbers into the formula and get the height of the skate. H \u003d L x A \u003d 3 x 0.84 \u003d 2.52 m. The height of the roof ridge is 2.52 meters.
Roof truss frame
Reliability is the strongest guarantee of the durability of any building. Therefore, the design and installation of all roof units should be given the same special attention as all other main parts of the house - its foundation, load-bearing walls and ceiling.
All structures use typical principles and rules, according to which the truss system of the building is built, and all nodes of the roof device are strengthened. The frame is installed on the basis of the upper crown, called the Mauerlat, which can be made of wooden beams, concrete or brick bases. If wooden beams are used, then the beams are mounted on bolts or threaded rods embedded in the upper part of the wall.
The logs are drilled for each reinforcing bolt, and the beam is mounted on them around the entire perimeter. In addition to the bolted connection, the longitudinal beams are strengthened with transverse mortise locks, which are cut out on the lower and upper beams. There are several designstruss frame. And in how to make the roof more economical and efficient, you need to know which system is most suitable in certain conditions.
To cover large spans, hanging rafters are used, which are reinforced with sliding supports. In addition to them, the hanging structure uses an upper transverse beam, which is installed closer to the ridge. The structure of the layered frame is created from rafters, which are fixed with several fasteners. These are vertical supports, and slopes, and nodal connections.
How to choose materials
Materials for the house, including for roof insulation, must be selected based on their quality indicators regarding elasticity, temperature changes and resistance to destruction under the influence of external factors. The modern construction industry has in its arsenal many types of roofs that have high quality indicators.
Starting building your own home presents the builder with a difficult choice of material. There are no exact rules here. But there are still some tips in choosing a roofing material. The first step is to pay attention to the cost and configuration of roofing elements. Each type has a number of components for installation. The second rule in choosing a coating is that the material is suitable for the building configuration, roof structure, slope and type. For example, low-slope roofs require a tougher material, metal tiles.
The choice of roofing material is also connectedwith climatic conditions. In areas with abundant rainfall, it is advisable to choose by quality and strength. But for a flat system, it is better to use durable PVC membranes.
Installation of the roof roof
To prepare the installation of roofing material and insulation, a truss frame is laid. A flooring made of wooden slats with a cross section of at least 40 mm is installed under the hard one.
For a soft covering of any configuration, including a shed roof, you need a solid flooring of wooden boards or plywood. In both cases, the flooring creates additional reinforcement of the truss frame and a flat surface for installing sheets. The next installation process is the laying of a waterproofing film, which is made on a wooden deck. To create a ventilation gap between the roofing layer, an additional crate with a wooden plank with a cross section of no more than 10 mm is installed along the waterproofing film.
The coating layer is installed on an additional crate according to the general rules, depending on the material used. After the flooring, insulation is made, which is installed from the side of the attic. The insulation layer is covered with a vapor-tight film and covered with a facing material. Thus, the roof roof consists of several layers that create reliable hydro and thermal insulation.
