The roof protects the building from the penetration of adverse atmospheric phenomena into the premises. To guarantee the reliability and strength of roof structures, it is necessary to choose the type of roof and know all its structural elements. The load from the cover and snow cover is borne by the rafter system. Most often, a hip roof becomes the most optimal option. But what is she like?
What is hip
The hip roof structure is a four-slope system. In the center of which is a ridge or just a junction point of the ramps. Roof slope - incline,
This type is best suited for covering buildings that are close to a square, that is, having a large width. When erecting, there are no gables, walls along the entire perimeter of the same height. The optimal value of the angle of inclination in degrees will be a value from 20 to 45.
Its main parts are:
- slopes (with a simple roof of a rectangular or square shape, 4 slopes are formed);
- ridge - the topmost part of the roof;
- cornice - the lower part of the roof.
Hip Roof Features
The device of the rafter system of the hip roof suggests the presence of the following elements:
- Rafter legs (rafters) - the main supporting structures (available only for rectangular hips), are inclined beams resting on one end on a Mauerlat and the other on a ridge bolt.
- Shakers - rafter legs, resting the upper and lower ends on the sloping legs. Mauerlat often acts as a lower support. These elements are the main structural parts of a square hip roof. With a rectangular shape, the buildings in the plan are used in conjunction with ordinary rafters, the pitch and cross section coincide.
- Sloping legs - diagonal rafters forming end slopes. At the bottom, they rest on the corner of the building. They usually have a larger cross section than ordinary rafter legs. They are supported by sprinklers.
- Ridge crossbar - a horizontal beam located in the central part of the building (absent with the square shape of the structure). The design of the hip roof assumes the presence of racks on it (with a gable roof, bearing occurs on the gables). It is the upper support for inclined beams.
- Mauerlat - a beam installed along the edge of the wall from the inside. Provides a lower support for rafters, evenly distributes the vertical component of the load on the walls and perceives the horizontal (spreader). In a timber or log house, the upper crown of the wall structure serves as a Mauerlat.
- Struts - inclined racks supporting the rafters, oblique legs or crossbar. Intermediate bearings can reduce the cross-section of the bearing elements. The rafter system of the hip roof involves the installation of struts at an angle of 60 or 45 degrees relative to the horizontal plane.
- Racks - vertical intermediate supports.
- Sprengels - horizontal beams diagonally stacked in the corner of the building. They provide support under the rack installed to support the oblique legs. This design transfers the load to the perpendicular walls and is used when it is not possible to install the rack on the ceiling. For example, in the middle of a reinforced concrete slab, it is impossible to install a support stand, since the slab can withstand a certain load, in which the main component is the mass of furniture, equipment and people.
- Scramble - the horizontal element that pulls together the rafters preventing them from dispersing can be located in the Mauerlat level or higher.
- Crate - boards or bars of a small cross-section, laid perpendicular to the rafters on top of them. They serve as the basis for roofing material. A hip roof with your own hands is often erected with the installation of a sparse crate (through one board), but you need to remember that in particularly critical places (valley, cornices), the crate is solid.
- Counter grill - bars or boards of small cross section. In the construction of the roof are not always used. They are installed on top of the rafters, parallel to them under the crate. They are needed to raise the crate above the insulation between the rafters, thereby providing the necessary ventilation gap.
- Mares - boards attached to the lower end of the rafters, providing the necessary overhang of the cornice.
Some of these elements are absent in the construction of a simple roof, mandatory structures for the hip are:
- spruces;
- sloping legs;
- Mauerlat;
- crate.
Preparatory work
Before you make a hip roof, you need to make several design decisions, namely:
- rafter pitch;
- section of rafters and oblique legs;
- roof pitch
The pitch of the rafters depends on the purpose of the roof space and the width of the building. The larger the span of the rafter leg, the less you will have to take a step. If the space under the roof will be used as an attic or a heated attic, additional insulation will be required.
Warming is carried out using three types of materials, depending on which the step is selected:
- rigid mineral wool slabs - rafter pitch 58 or 118 cm;
- polystyrene foam (polystyrene or extruded) - rafter pitch - 60 cm;
- polyurethane foam (foam) - any step.
These values are due to the convenience of workers. If we take a step of load-bearing structures of 58 cm when using mineral wool, then convenient installation of standard plates with a width of 60 cm will be ensured.
The manufacturer recommends that the thermal insulation material be several centimeters wider than the distance between the rafters clean, this will ensure the most tight fit and prevent the appearance of cracks and cold bridges. The purpose of the size of 118 cm provides for the laying of plates in two stripes in width.
When using expanded polystyrene with a standard width of 60 cm, installation with a spacer is not required. The material is held between the supporting structures due to glue, special nails and the lower lathing. The gaps between the wooden elements and the plates of the insulating material are filled with mounting foam or sealant.
Polyurethane foam in the form of foam removes the requirements for the rafter pitch. The material can take any form given to it, which ensures freedom of action in this matter.
If skylights are installed, their dimensions also need to be taken into account. The distance in the light between the inclined beams is 4-6 cm greater than the width of the window. If roof insulation is not provided, choose a convenient rafter pitch, usually 1 meter.
The cross section of the rafters is accepted by calculation, but in the general case, you can specify the following values:
- 5x15 cm for flights up to 3 m;
- 5x20 cm for flights up to 4 m;
- 7.5x17.5 for flights up to 5 m;
- 7.5x200 for flights up to 6 m.
Values are given for rafter pitch 0.9. With increasing distance, it is necessary to increase the cross section. The cross section of the legs is also taken a little more.
Mounting
A hip roof with your own hands is a feasible task, but you need to know the main nodes of the connection of structures.
The connection of the rafter legs at the top point depends on the type of rafters. They may be:
- layered;
- hanging.
Nomads on top are supported by a crossbar. To do this, a notch is made in a horizontal beam. Fastening is done with nails.
Hanging rafters provide for the absence of a crossbar. They are most often used if necessary, the organization of free planning and the absence of a central wall. In this case, there is no support under the junction. Inclined beams are fastened together on nails. Additionally, at the junction, they provide wooden linings with a thickness of 22-25 cm on both sides of the rafter legs. These pads are pulled together with studs or bolts.
To fix the rafters at the lower point, a notch is made in the Mauerlat. Inclined elements are mounted and secured with nails or metal corners. Scaffolds are attached to the nasal elements end-to-end, on the same level.
To resist the roof to wind loads trying to tear it off, twists of wire are provided that connect the lower end of the rafters to the wall. In the wall, the twist is fixed to a ruff (fixing device).
When constructing walls made of wooden materials, staples can be used instead of twists. Twists or staples are installed on each rafter leg or through one.
If you build the rafter system correctly with a competent selection of the cross-section and step of the rafters, the roof will last a long time.