When constructing a roof for an attic, it is sometimes impossible to ensure its normal height with the same angle of inclination throughout the ramp. In this case, the broken roof of the house comes to the rescue, the rafter system of which is slightly more complicated than that of a conventional gable roof. Before you build such a structure, you need to understand its basic elements and nodes.
What is a sloping roof?
It is typical for houses with the attic. It has two slopes on two sides. A ramp that is closer to the cornice has a greater angle of inclination than one that is closer to the ridge.
A device of this design is technologically more complicated than a conventional gable roof, but it allows you to win at the height of the room. Instead of an attic with a sloping ceiling, the owner gets full rooms. This is achieved by the fact that slopes with a large angle of inclination play the role of continuing the vertical walls, and with a smaller one, the ceiling.
The main elements of the system
Before you make a sloping roof, you need to understand its basic elements. The design consists of:
- rafter legs, which form a steeper slope (layered rafters - inclined beams resting on two sides, from below - to the Mauerlat, and from above - to the crossbar);
- hanging rafters, which form a gentle slope (spacer structure, bearing only occurs from below, the spacer is perceived as a scrum);
- Mauerlata - beams, which is laid on the inner edge of the outer wall and allows you to evenly distribute the load from the rafters.
- runs (crossbars), there can be 2 or 3 of them in a sloping roof (there are always two, they serve as the upper support for the rafters, in some cases they provide a third run in the ridge, in this case all the inclined beams of the system become layered, there are no hanging rafters);
- racks for runs, which will serve as a frame for the longitudinal walls of the attic (can be installed with a step under the insulation, which will facilitate its installation);
- strut systems the design allows you to unload the rafters;
- ties (contractions, puffs), the device of which is provided at the level of the kink of the slope (serves to perceive the thrust from the hanging rafters and as a frame for the attic ceiling);
- pendants (headstock), which is provided for a long length of the contractions and prevents sagging.
Material selection
To build a reliable attic roof, it is necessary to carefully control the quality of the materials used. For structural elements, it is worth choosing wood of the first or second grade. Quality is also affected by the time and place of harvesting. The best option is a material with the following characteristics:
- Origin - conifers. Due to the resin content, they are more resistant to decay and destruction. One of the best building materials can be called larch, then pine and spruce take their positions.
- The place of growth is the northern regions. The harsher the tree’s growth conditions, the slower it grows. In this case, the annual rings are located as close as possible to each other, increasing strength.
- Felling time is the end of winter, the beginning of spring. Again, the completion of growth in winter conditions creates a more durable material for construction.
In addition to high-quality wood, roofing is impossible without antiseptic treatment of all elements.
If necessary, the structure is also treated with flame retardants, which increase resistance to fire.
Production technology
The rafter system of a sloping roof is described step by step. This makes it easier to understand the upcoming work. The mansard roof is built in the following order:
- Installing Mauerlat on the walls. The fixing method depends on the material of the walls. On a brick or concrete beam, it is laid on a previously prepared layer of waterproofing. You can use roofing (obsolete version), roofing material, linocrom, hydroisol or other bitumen roll materials. Fastening is carried out on the anchor previously laid in the wall. For wooden houses, you can consider mounting on staples. On average, the Mauerlat section is taken 100x100 or 150x150 mm.
- Installation of runs and racks under them. Depending on the design of the building, the drains should be based either on floor beams or on load-bearing walls. Installation on a span of reinforced concrete floors is not allowed. The device depends on the insulation used: for mineral wool, it is better to put racks in increments of 0.58 m, for expanded polystyrene - 0.6 m, for polyurethane foam, the step of the racks is not of great importance. The cross section is most often used for the crossbar as for the Mauerlat, the stand can be of the same cross section as the crossbar (100x100, 150x150 mm).
- Stacked rafters. Mounting to the Mauerlat and the crossbar is made by a notch. For fixing, nails or steel corners with self-tapping screws are used. Additionally, on each or through one rafter leg, fastening to the outer walls is performed. To do this, lay a ruff in the wall. From an inclined beam to a ruff a twist of double wire with a diameter of 3-4 mm is drawn. In a wooden house, instead of twisting and a ruff, you can use staples. The cross section of the rafters is taken depending on their pitch and the material of the roofing.
- Set struts. To attach the strut to the leg using nails and a thrust bar.
- Installation of farms. The farm consists of hanging rafters, scrum and suspension. The structure can be assembled directly on the roof or on the ground. The legs are fastened together at the upper point by means of overlays on both sides. The fight can also be double (on the board on each side). All fastenings are made on nails, bolts or studs. Studs or bolts are accepted with a diameter of 10 to 14 mm on average.
- Laying a waterproofing layer.
- Upper crate.
- Installation of insulation.
- Vapor barrier and bottom crate.
- Laying roofing material.
- Sheathing of the gable frame.
- Hemming and attic finishes.
Wood treatment with antiseptics and flame retardants can be carried out both before and after the assembly of the roof structure. It’s best to complete this activity immediately after purchasing the material.
Space lighting
The attic device involves two lighting methods:
- dormers;
- roof windows.
A sloping roof with your own hands complicates the installation of skylights, since most often the role of the walls of the room is performed by the racks.
In this case, the space is limited by the casing for racks and contractions. There is no space left for installing skylights. In this case, provide windows in the gables and dormer. The auditory window of the simplest design is a “birdhouse”. It has walls and slopes based on them.
If you do not plan to sheathe the space on the racks, then you can install skylights. They will give the room a special cosiness.
Proper installation of elements will allow you to get reliable protection of the interior for a long time.