Hinged roof system - construction and drawings
The rafter system is a combination of all the supporting elements that form the skeleton on which the roofing pie lies. The ability of the roof to withstand wind and snow loads and to protect the interior from water and cold depends on the strength and reliability of this foundation. In order not to resort to the expensive services of firms performing roofing work professionally, we will tell what the roof system of a four-pitch roof consists of, what materials are required for its manufacture and how to assemble it.
Types of hipped roofs
The name "chetyrehskatnaya" combines several types of roofs, consisting of four planes, slopes:
- Hip. Its design includes four slopes of two geometric shapes: two of them are in the form of a trapezium, two are triangular. Triangular slopes replace the gables of the structure. On the one hand, this is a plus, as it is possible to save on material for walls, and on the other, a minus, because the lack of gables does not allow for the installation of ordinary vertical windows.
- Gutter Dutch. In fact, it is referred to as dvuhskatnymi types of roofing, then to the slope. In confusion of roofers enter the truncated face slopes, hips. They do not replace the pediment, but modify it to a trapezoidal shape. The Dutch roof looks very original and is great for building in windy areas due to the reduced effect of windage.
- Half-hardened Danish. Hips of this type of roof do not cut off the upper part of the gable, but the lower part, forming a slope of usual length. And under the ridge with such a construction, a small pediment in the form of a triangle is left, which nevertheless allows saving on dormer windows and organizing more accessible vertical lighting.
- Tent. Hip roof is used for buildings that have a square shape. It consists of four skates, which are isosceles triangles and converge at one point, without forming a skate.
In spite of external differences, the truss systems of the four-sloped roof are made of the same elements, guided by the same rules.
Types of roof systems
The rafter roof system of the four-pitched type takes on a different appearance, depending on the initial conditions: the area of the house to be covered and the internal layout. There are three types:
- Висячая. Применяют для сооружений, в которых нет внутренних несущих перегородок, поэтому опора осуществляется лишь на внешние стены. Hanging railing system четырехскатной крыши испытывает нагрузки на изгиб, сжатие и распирание. Чтобы уравновесить воздействующие силы вводят дополнительные, уравновешивающие элементы – затяжки, ригели, бабки. Сложность конструкции заключается в обилии составных частей, высоком расходе материала и, как следствие, большом весе, выдержать который способен лишь основательный фундамент.
- Outrageous She settled in houses, in the middle or on the sides of which there are internal load-bearing walls. The rafter system in this case is supported not only on external, but also on internal walls. The rafter-reinforced truss system is more reliable and balanced, it is easier and cheaper to mount it.
- Combined. Consists of elements of naslonnogo and hanging truss system. It is used if not an internal wall, but columns or pillars are used as an additional support. Then the hanging rafters alternate with the nased, forming an openwork design with open floor beams.
A type of roof system is suitable for a particular house, determined during the design period, making calculations and drawing up drawings.
Calculation of slope slopes and height of the ridge
The drafting of the roof system of the four-slope roof begins with the calculations that determine the geometry of the future structure:
- Calculation of slope ramps. Professional designers perform a calculation based on trigonometric formulas that calculate the slope of the slope through the cosine of a triangle with a given base equal to the width of the house. But novice builders can use reference tables that provide recommended slope values for zones of various wind and snow loads, and various roofing materials. Among these factors determine the limiting, which will be optimal for this construction. Note that the angle of inclination from the cat in the range of 45-55 degrees is suitable for most projects. However, the steeper it is, the more materials are spent during construction.
- Расчет высоты конька. Его ставят на второе место потому, что для вычисления требуется известный угол наклона скатов. Для определения параметра также используют тригонометрические формулы, представляя стропильную ферму как треугольник с двумя рассчитанными углами и известным основанием. Важно учесть, что, если чердачное помещение будет использоваться не только для хранения, конек размещают, принимая во внимание желаемую высоту потолков мансарды. Hipped roof имеет коньковый узел, так как все стропила сходятся в одной точке.
Facilitate the process of designing a truss system chetyrekhskatnoy roof can special computer programs, calculators, which requires only the entry of the initial data: the size of the house, the number of ramps.
Load calculation
The next stage of design - determining the composition of the elements of the truss system and their section. To do this, perform the calculation of the loads, which is subjected to chetyrehskatny design. They are divided into three types:
- Permanent. Their hip roof is experiencing all the time. In this type include the weight of the roofing pie, truss system, attic floor, if you plan to use the attic as a living space. Do not forget that the snow drainers drainage system - this is also an additional load, which bears the roof.
- Temporary. The structure is not constantly subjected to the action of these loads, but only from time to time, in the remaining periods it is minimal. We are talking about snow and wind load, the weight of thawed and rainwater, the mass of a person performing repairs and maintenance of the roof.
- Special. This item is relevant to residents of areas with increased seismic or hurricane danger. The four-slope roof is designed with regard to possible extreme loads in order to secure the people under it.
Summing up the values of all loads, they determine the total, which, depending on the roofing material used, can reach 180-250 kg per square meter. Based on this figure, determine the number of elements of the truss system and their section, referring to the reference table. More complex systems are more convenient to calculate in special programs, the result of which is a ready-made diagram of a truss system of a four-rolled type roof.
Main elements
The rafter roof system consists of a plurality of component parts, mandatory and auxiliary:
- Mauerlat A beam section of 100x100 mm or 150x150 mm, evenly distributing the load around the perimeter of the load-bearing walls. The difference between the four-sided roof is that four power plates are required for its installation, and not two, as for a dual-sided roof.
- Sill. A bar that serves as a support for the pillars, which is used in a slanting truss system. He, like mauerlat, distributes the weight of the roof, but is located on the inner bearing wall.
- Rafter legs. Elements of boards with a section of 50x150 mm or 100x150 mm, which carry the roofing pie and set the geometry of the ramps. In the construction of four-pitched roofs use common, slat and floor rafters. Privates are arranged in pairs along the ridge girder, forming trapezoid slopes. Wicked, going from the ridge to the two corners of the house, form the end triangular slopes. And rafter rafters are based on the top of the slats and have different lengths.
- Ridge run. Timber, based on vertical racks, to which the rafters are attached. This is the highest point of the roof.
- Racks. Vertical props that set on the ground. They support the ridge girder or the middle of the truss foot.
- The struts. Bars, which are set at an angle to the rafter legs to prevent them from bending.
- Tightening and bolt. Horizontal jumpers made of wood or metal, connecting pairs of rafter legs, reducing the bursting load on the walls. The bolt is installed in the upper part of the rafter, in the tightening at the bottom, often using as floor beams.
- Sprengel farms. Sprengel - vertical riser for stitched rafters. If there is nothing to rest against it, set the tightness between the two adjacent sides of the house and use the metal corners to attach a Sprengel.
- Crate. The basis for the flooring of roofing material. If the boards are nailed without gaps, the design of the batten is called solid. And if the boards alternate with a small clearance - lattice. The sheathing scheme depends on the type of roofing material.
- Eaves. Part of the rafters, which is 40-50 cm in favor of the perimeter of the house, protecting it from moisture.
Build a truss system
With a drawing of the truss system in hand, you can begin assembly work. Since natural wood is mainly used as a material, it will not be superfluous to treat it with an antiseptic of deep penetration to protect against moisture and bacteria. Roof masters draw on a number of features that should be taken into account when installing the truss system of a hipped roof:
- It is difficult even for a very experienced worker to carry out work on assembling the roof alone due to the large length and weight of truss legs and pillars.
- Since some elements of the truss system are long, in particular diagonal rafters, standard sized sawn timber is not suitable for their manufacture. This problem is solved with the help of composite trusses of two or even three parts.
- If the lengths of the rafters are not enough to form the overhang, they are put in place by fillys made of boards of smaller section.
Competently calculated and well-assembled truss system is the basis of long-term operation of the four-slope roof, which will become a reliable weather protection, regardless of whether it is a tent roof or hip!