Hipped roof: design features of the truss system, do-it-yourself device, video instruction, photo

In this article, a hipped roof will be considered - the design, calculation and arrangement of the truss system.

The hipped roof is a four-pitched structure, the base of which is a quadrilateral, from which four isosceles triangles converge to the upper central point. Such a roof device allows you to save on building materials, since it does not require the arrangement of gables. At the same time, the appearance of the roof remains quite attractive and aesthetic.

A hipped roof structure can be made independently regardless of the type of building, although the best option is a building with a square base.

The device of a hipped roof is a rather complex system and requires the developer to have certain knowledge and skills. Before you begin the construction of such a roof, you should carefully and competently perform all the necessary calculations.

Content

Hip roof calculation

The hipped roof includes four slopes, which are isosceles triangles in shape. If the base of the roof has a square shape, to calculate the area of \u200b\u200bthe roof, it is enough to calculate the area of one slope and multiply by four.

If the base is a rectangle, then the first step is to calculate the sum of the areas of two different rectangles, and then multiply it by two.

The area of the slope, which is an isosceles triangle, is calculated by the following formula:

S=2x(bxh),

where S is the area of the slope, b is the length of the base of the triangle, h is its height. After that, you should also calculate the area of the overhangs of the cornices, which are isosceles trapezoids. To do this, multiply the height of this figure by half the sum of the lengths of its bases.

At the same time, the hipped roof device provides for two options for performing calculations:

Using the height of the ridge, as well as the length of the entire base roofs;
Considering the length of the diagonal rafter leg and the length of the perimeter of the base.

In addition, you should also take into account various additional elements that a hipped roof includes:

Diagonal (sloping) rafters);
Spooks;
Racks;
Mauerlat;
Support bars;
Lie down, etc.

Here is an example of self-calculation of the hipped roof area, taking into account the above data:

The dimensions of the building are 6x6 meters;
The height of the ridge is 2.97 m;
The length of the diagonal leg of the rafter is 5.21 m;
The slope angle of the slopes is 35 °;
The width of the overhang of the cornice is 60 centimeters.

According to the first calculation option, we calculate the length of the height of the triangle: for this, the Pythagorean theorem is used:

h² = a² – (b/2)² = (5,21)² – (6/2)² = (4,24)² m,

where h is the height of the triangle, a is the length of the slope, b is the width of the base. Further, using the formula, you can calculate the area of \u200b\u200bone slope in the shape of a triangle, which will be equal to 12.72 square meters.

Due to the fact that the base on which the hipped roof is erected is a square, the side of which is 6 meters, the resulting area should be multiplied by 4, as a result we get a total area of \u200b\u200bthe slopes, which is 50.88 square meters.

Next, you should calculate the area of \u200b\u200bthe overhang of the eaves. The length of the smaller base of the trapezoid is already known, it is six meters. The calculation of the length of the second base is done using fairly simple formulas used for trapezoids.

As a result of the calculations, the length value was obtained, which is 7.04 m, and the area will be equal to 4.76 m². To calculate the total area of overhangs, as in the case of the roof itself, the resulting area should be multiplied by four.

The total area of the hipped roof is calculated by adding the resulting areas and is equal to 50.88 + 4.76x4 = 69.91 m².

truss system

After performing the calculation of the roof area, we proceed to the calculation of the structural elements that make up the truss roof system.

Here it should be borne in mind that for hipped roofs two variants of the rafter system can be used - hanging and inclined, selected depending on the type of fastening:

Self-assembly of a hanging system is a rather complicated procedure, and its repair with your own hands can take quite a long time.
This type of construction is most often used if the building does not have internal walls and support points. rafters located only on the load-bearing walls of the building.
The second option, used when a hipped roof is being built, is a rafter system., characterized by a simpler installation procedure and low manufacturing cost.
For the construction of such a structure, a medium load-bearing wall and intermediate columnar supports installed on a reinforced concrete base are required.
This system is most widely used in the construction of hipped roofs, the slope of which exceeds 40 °.

Let us consider in more detail the main elements that include hipped roofs erected independently:

Slanted rafters directed from the side of the corners of the walls - rafters resting at one end on the Mauerlat, and at the other - on the legs of the rafters.
This element carries a rather significant load, since the sparrows rely on it;
The sprockets and the roof are shortened multi-span legs of the rafters;
Racks and struts used as a support for rafter legs;
Crossbars used in case of legs resting against each other in the area of \u200b\u200bthe ridge;
Beds laid on an inner wall or on special brick posts and serving as a support for racks and struts;

Important: the minimum cross-section of the columns for supporting the beds is 10x15 cm, and waterproofing (rolled) must be laid under the beds themselves.

Runs - beams located parallel to the Mauerlat, the installation of which depends on which design is chosen for floors and walls, i.e. on whether there is an opportunity to lean them on something;
Sprengels, which are additional supports for the construction of a hipped roof. Most often they are made of timber or logs.

Depending on what material is chosen for the construction of the house, its system of rafters under the hipped roof can be based on the following elements:

In wooden frame buildings - the upper trim;
In stone and brick houses - Mauerlat;
In the case of log cabins - the upper crowns.

The choice of roof dimensions and the manufacture of rafters

Elements such as racks, rafter systems, struts, crossbars and others that carry significant weight are made from the highest quality wood possible, on which there should be no knots.

The tree must be properly dried, making sure that there are no cracks on it, the depth of which exceeds 1/4 of the length of the whole beam.

Useful: it is most advisable to use coniferous wood for the installation of these elements, which has sufficient strength and resistance to various dynamic and mechanical effects on the roof.

The rafters on which the hipped roof is erected can be composite or paired:

Composite rafters include two boards that are moved apart by a distance equal to the thickness of the liner (1-2 board heights).
In this case, it should be taken into account that the distance between individual liners can reach seven times the height of the board itself, and a single wooden board can be installed in the upper part.
Paired rafters made of boards, between which there should be no gaps. Typically, this type of rafter is used in the process of manufacturing diagonal slanting elements along with beams and logs.

The sections of individual rafters can be influenced by a number of factors:

Rafter step;
The angle of the roof;
Snow load;
Span size, etc.

Consider also the values of the main parameters used in the construction of a hipped roof:

The length of the legs of the rafters is less than 3 meters: the pitch of the rafters is from 110 to 135 cm, the thickness and width of the board are 10 and 8 cm, the diameter of the log is 10 cm;
The length of the legs of the rafters is from 3 to 4 meters. The pitch of the rafters is from 140 to 170 cm, the thickness and width of the board is 9 and 10 cm, the diameter of the logs is 15 cm;
The length of the legs of the rafters is from 4 to 5 meters. The pitch of the rafters is from 110 to 135 cm, the thickness and width of the board are 8 and 20 cm, the diameter of the logs is 20 cm;
The length of the legs of the rafters is up to 6.5 m. The pitch of the rafters is from 110 to 140 cm, the thickness and width of the board is 12 and 22 cm, the diameter of the log is 24 cm;
The dimensions of the material for the manufacture of runs: a log with a diameter of 16 cm or a bar with a section of 10x5 cm;
Dimensions of the material used for the manufacture of Mauerlat: log diameter - 12 cm, beam section - 10x5 cm;
The material used for struts, crossbars and racks: the diameter of the log is 12 cm, the cross section of the beam is 10x5 cm.

Important: at the same time, it is necessary to join the sprigs in a run, and the length of all rafter legs should be the same.

The angle of inclination of hipped roofs is most often 40-60 °, but depending on the chosen roofing material, the value may be slightly different:

The angle of inclination for tiles is 30-60°;
For sheet and asbestos-cement materials - 14-60 °;
When covered with roll materials - from 8 to 18 °.

The procedure for the construction of a hipped roof

Conventionally, the process of building a hipped roof can be divided into several main stages:

Roof design and calculation;
Selection and acquisition of the necessary materials with appropriate dimensions and characteristics;
Laying a support beam (Mauerlat) under the feet of the rafters or for the entire length of the house:

- In the case of a brick house, it is advisable to put a Mauerlat on the inner surface of the walls, and between it and the wall a waterproofing material is laid, for example, roofing material, and a grate is mounted to prevent sagging of the legs of the rafters;
- In the case of a wooden house, the role of the Mauerlat can be assigned to the upper part of the log house.

In the upper part of the truss structure, a run (support beam) supporting the rafters is placed parallel to the support beam.

Important: the distance between the power plate and the run should not exceed 4.5 m.

Braces, struts and diagonal braces are mounted in the slopes of a hipped roof to resist wind loads from the side of the gables;

Useful: diagonal ties are usually made from boards 25-45 cm and nailed to the base of the rafter legs.

The hipped roof is insulated by laying vapor and waterproofing, and then - roofing.

This article presents the design features, the main parameters and methods for calculating the hipped roof, as well as the values of the main indicators used in its construction. Using the knowledge gained from the article should greatly facilitate the process of building a hipped roof with your own hands.

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