In the construction of country houses and cottages, the use of a four-pitched roof, or, as it is sometimes called, a hip roof, is becoming increasingly popular. The main feature of this type of roof is the additional triangular slopes that form the hip rafters.
These rafters are joined to the ridges of the gable roof.
Features of a hipped (hip) roof
In principle, a hipped roof consists of two parts:
- gable roof, consisting of two trapezoidal slopes that do not completely cover the area of \u200b\u200bthe house in length;
- two triangular hips covering the uncovered areas of the house.
Currently, the hip type of roofs is the most economical in terms of the use of building materials, the construction of the hip system is considered the most labor-intensive. The main difficulty in the construction of a four-pitched hip roof is the accuracy in marking, since the slightest deviation can lead to the need to redo all the work.
Types of hip roofs
The following types of hipped roofs can be distinguished:
- hipped roof - such a roof is installed over a building, the base of which is a square. It includes four triangular-shaped slopes.
- Half hip (Danish roof) - the hips are not set to full height, that is, they do not reach the roof ridge, but are truncated from above.
- Semi-hipped mansard roof - in this case, the hips are also not installed at full height, but are truncated from below - small triangular hips are installed above the attic gables.
- Sloping pitched roof - such a roof has slopes of various steepness (one of the most complex types of hip roof in design).
Hip roof device
Consider the main elements of the truss system of a hipped roof, shown in the figure:
- Hip rafters (they are also called oblique or diagonal). They rest with one end on the ridge beam, and with the other on the walls of the house (or rather, on the Mauerlat, which is a beam laid along the perimeter of the walls).
- Short rafters that do not rest on the ridge beam, but on the rafters.
- Skate bar.
- Central rafters - are joined at the ends of the ridge beam with slanting rafters.
- Ordinary intermediates rafters - are joined with a ridge beam.
Roofing stages.
The first stage in the construction of the roof is the installation of load-bearing beams. Depending on the complexity of the roof structure, several types of load-bearing beams are installed. For simple structures, only the Mauerlat is installed, which we have already mentioned - this is a wooden beam along the perimeter of the walls, on which the rafters will rest.
In more complex structures, load-bearing beams are installed across the building (for example, on internal load-bearing walls), on which racks will be attached for mounting the ridge span. In this case, a skate is mounted on these beams.
When installing a ridge span, the most important thing is to maintain the dimensions in height, as well as the exact location of the ridge. In this case, the racks for the ridge span are fastened with special jibs.
Then comes the turn of the most crucial stage of the installation of the hip truss system - laying the rafters. In order to avoid problems in the future, you need an accurate marking of the rafters, including the need to determine their exact length.
As a rule, the length of the rafters is set so that their lower part extends beyond the edge of the wall, forming a cornice that will protect the walls of the house from rain and other precipitation. For proper protection, the protrusion must be at least 40 centimeters.
The length of the rafters can be calculated using the Pythagorean theorem. To do this, you need to measure the height of the ridge and the length of the projection of the rafter leg in the horizontal plane - from the corner of the wall to the projection of the end of the ridge beam.
Thus, we will get the lengths of the two legs of the rectangle and it will not be difficult to calculate the length of the hypotenuse. Naturally, the length of the overhang will need to be added to the resulting length.
Example: if the base of the triangle, that is, the width of the house with cornices (c), is 11 meters (10 m + outlet for cornices on both sides of 0.5 m), and the height of the roof (b) is 5 m, according to the Pythagorean theorem, the length rafter legs (a) will be: a \u003d √ (b² + (c / 2)²) \u003d √ (5² + (11/2)²) \u003d 7.43 m.
The installation of diagonal rafters is a very important stage in the construction of a hipped roof, since it is these rafters that form the planes of future roof slopes. It is necessary that all diagonal rafters are the same length, and the four roof slopes are perfectly flat planes.
It should be noted that the rafter leg is the longest and carries an increased load. That is why you need to think about strengthening it. For strengthening, you can lay a double diagonal rafter, or install special props.
If the rafter is sewn from two boards or beams, it is necessary to calculate the place of connection of the parts of the rafter leg so that it falls on the support post. If there is nothing to install supports on, it is possible to install a trussed truss or a trussed truss to strengthen the rafter.
The truss truss is installed at the corner, between adjacent walls.
When installing a hip truss system you need to pay attention to the insertion of various elements in the docking nodes. One of the most difficult docking nodes is the place where the ridge beam, two slanting rafter legs and three central rafters are joined.
After the diagonal and central rafters are mounted and fixed, intermediate rafters are installed.
Among them are:
- Ordinary intermediate rafters.
- Short (angular) rafters;
When installing conventional intermediate rafters, the most important thing is to determine the distance between them for uniform installation. In order to correctly determine this distance, you need to measure the length of the ridge, and then divide the resulting value by a number greater than the number of intermediate rafters by one unit.
This will be the correct distance between the rafters.
Example: if the length of the ridge (b) is 10 m, and the number of intermediate rafters (c) is 6, then the step of the rafters (a) will be a = b / ( c +1) = 10 / (6 + 1) = 1, 43 m
Corner (short) rafters are laid with their upper part on the rafters. The size of the corner rafters varies depending on their location. The closer such rafters are to the corner of the building, the shorter they are.
When installing corner rafters, it must be borne in mind that the corner rafters of the hip (triangle) and the corner rafters of the gable system (trapezium) must be connected in pairs. This is very important for the strength of the structure.
Features of the construction of a hip roof
There are several nuances that need to be considered when constructing a hipped roof. First of all, these are the dimensions of the house itself, which accordingly affect the dimensions of the roof. If a country house or cottage has a large width, then the possibility of sagging rafters must be taken into account.
This mainly concerns the diagonal and central intermediate rafters.Therefore, in the case of a large width of the house, it is necessary to carry out a set of additional works related to the strengthening of the roof truss system. To do this, racks are installed under all long rafters, which are then reinforced with jibs.
Also, sometimes another method of strengthening the rafters is used - several racks are installed along the entire length of the roof, on which a longitudinal beam is placed under the rafters. Such a beam is usually installed under the very center of the rafters and takes on the main load from the weight of the roof.
It should also be noted that when arranging a complex hipped roof, for example, when combining a hip structure with a mezzanine, the weak point of this design is the rafter leg of the groove, so measures must be taken to secure it.
Modern urban planning and architectural standards impose rather stringent requirements on the construction of roofs, so all wooden elements of the cottage roof should be treated with a special fire-fighting and antiseptic impregnation.
In conclusion, it should be noted that the hip rafter system is one of the most reliable, durable and aesthetic roof structures. Despite the fact that this form of roofs has been used for quite a long time, right now it has become the most popular in the construction of country houses and cottages.
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