Feet for roofs

Mikhail Skvortsov Rafter system, based on the load-bearing walls, which in turn transmits the load foundation, complete skeleton of the building. The choice of the rafters to a large extent determined by the type of roof, and the differences here, as the cost can be very serious. As a rule, truss system is not visible. Like the human skeleton. However, hardly anyone would deny the importance of the original frame, which imparts to the human body strength and stability. Likewise, the roof rafters create a skeleton from which also requires stability, strength and durability. Moreover, these qualities must be provided regardless of the roofing material. Tile is on the roof, evroshifer or galvanized iron - in any case, the roof shall be securely protected from the weather and is guaranteed to keep the property in the event of any force majeure. In the first place - to keep the mechanical strength: it is impossible to roof, as they say, fell on his head. On the other hand, should take into account the nuances of the device truss system in the case of different roofing materials. Even a layman will tell you that roofing and natural tiles are different materials, at least in the mass. From this conclusion suggests itself: truss system in each case arranged in their own way, and the criteria here - the feasibility and cost of materials. Device roof system depends not only on the roofing material, but also on its configuration, namely the slope. As you know, the roof may have different slopes from zero (flat roof) to 45 degrees or more. It would seem, what's the difference? The difference is, because the same snow mass on different roofs behave differently: with a steeple, it easily slips on the same plane is delayed. And because the bias is not just a significant and very significant. Naturally, there are certain regulatory burden, which must withstand the roof and, accordingly, truss system. In our region, this load varies from 70 to 200 kilograms per square meter of horizontal projection of the coating. In addition to a constant load of dead weight truss system to withstand temporary load of snow cover, wind pressure on the windward side and vacuum on the leeward side, and the stresses arising during the operation (for example, when repairing or cleaning the snow from the roof). Nuances of the device, most projects is a gable roof cottage, in this case, the butt ends of vertical wall of the triangular shape and design of trusses is relatively simple. One question that arises in the course of devices such roof - is to determine the optimal height of the attic floor. The decision is influenced by many factors, but there are here and even desirable and mandatory conditions. For starters, that the truss system relies on a board, mounted on top of a bearing wall and called mauerlatom. So that's one of the requirements is to ensure the free passage of fire height of at least 1.6 m along the entire room, so that in the lowest places in the exterior walls remained on top of filling the attic floor is not less than 0,4 m to mauerlata . This would allow for periodic inspection and repair of the lower parts of the rafters, the most exposed to freezing and moisture, and provide fire safety. Bearing part of the roof, usually formed by a system of slanted wooden rafters - rafters. They are set at an angle equal to the slope of roof slope, and are based on the lower ends of the exterior brick or block wall through mauerlat - a special timber that is attached to the upper edge wall and serves to evenly distribute the load. Between the wall and mauerlatom laid two layers of roofing material. The upper ends of the rafters rest on podkonkovy bar or on the intermediate runs, transferring the load on the internal load-bearing walls through the racks. The overall stability of the roof system is provided by braces, braces and diagonal connections. Rafters are placed every 0,8-2,0 m, depending on their cross-sections, roofing material and other features. The lower ends of rafters through one should be secured to the wall from twisting the wire to keep the roof from a possible collapse in high winds. Twisting perpetuate a crutch or a ruff, scored in the seam laying on the 250-300 mm below mauerlata. For hipped roof (hip, two slope which is a trapezium, and two others, by the end walls, - triangles, which are called hips) the construction of roof system is somewhat more complicated. Bond elements in the wooden rafters produced staples, nails or screws. In homes with timbered walls or rafters are joined bruschatymi straps with the second upper crown. In order to access mauerlatov and lower ends of the rafters for the inspection and repair them have a 35-40 cm from the floor. In cases where the rafters are based only on two exterior walls (if there are no intermediate supports), they are called the hanging and represent the simplest type of truss, which is suspended (if any), the attic floor. In the roof rafters with spans of 6 m between the upper ends of rafters clamped suspended head (vertical bar). To avoid sagging construction to the lower end of the headstock is suspended by straps of flat steel and horizontal tightening of the run for supporting beams of the attic floor. With spans up to 12 m in the design of truss struts introduced, reducing the estimated length of the rafters. Stand under the beams are installed on the interior walls every 3-4 m, with a rack stacked boards (sleepers) and the strip of roofing or roofing. On the steeple roof slope exceeds 45 degrees, the snow will not actually detained, and hence the load on the rafters will be weaker. Therefore, the step of rafters can be without much fear of increase to 1.2 and even up to five feet. If the slope of the roof, on the contrary, a small risk of a snowdrift increases, therefore, step up to the rafters to reduce 0,8-0,6 meters. A more accurate calculation will help to make the specialist. That would be important section of the rafters, and the distance between support bearing structure - struts, braces and ridge girder. Average spacing of rafters is about one meter. The type of roof Naturally, the cost of roof system is primarily determined by the value of the material. The longer and thicker rafters, the more often they are used, the greater the need the more expensive material and therefore cost truss system. So if your choice was on the ceramic tiles, you'll need the rafters of a large cross-section and, consequently, more expensive than necessary under the asphalt roof. Complication roof system due to structural limitations or additional requirements for the roof of some types of roofing. For example, a square meter of ordinary shingles weighs about 50 pounds, so when using this material truss system should be designed for maximum load. Consumption of sawn timber and the cost of the roof in this case would increase by 15-20 percent. Soft ceramic tile is easier to five times, but for her need solid crate of boards or plywood and small slopes lining carpets, which also requires additional costs. Building regulations prescribe for severe types of the roof (of the same tile) used as a rafter beams 70 to 150 mm. In this step the rafters should be minimal - about half a meter. If, however, apply a light roofing material (roll, shingles, etc.), a bar should be smaller section - 50 to 150 mm, and the step is allowed to increase up to two meters. The difference in the cost of the material here can be substantial. Roofing material directly to the rafters do not fit - need to do crate. For a start along the rafters, repeating their pattern mounted kontrobreshetka then nailed across the rafters directly lathing, and the plank on which the roofing material. The presence of crates and kontrobreshetki gives the opportunity to make a solid carpet of the selected roofing material, but also provides structural strength. Because of these structural elements in the future on the roof, you can safely climb, walk on it, cleared of snow or repair the roof. In addition, due to being ensured normal humidity conditions: underlay the space ventilated, and all the excess moisture removed with a current of air. Kind of depends on the type of roof sheathing. For metal, for example, crates are assembled from bars 50 x 50 or 60 x 60 mm, rolled roofing materials make a solid flooring of thin boards or waterproof plywood. Wood furring should be dried, otherwise the design can deform and cause rapid deterioration of the roof. Most often the material for the roof systems of country houses is wood. This is a relatively lightweight material, it can be lifted up without the use of heavy machinery. If the walls are built not on a par, wooden rafters easy to adjust the size, took a superfluous or, alternatively, build, and directly on the roof. Elements of wood construction are easily mounted in many different ways, and roofing plank of wood is not difficult. Part of the roof system staple nails - this quickly and cheaply. Over time, however, when the tree dries out, such a compound shattered. Reliable connection with the bolts, and the most durable straps and clips provided. Only in exceptional cases, the rafters are using concrete or metal structures, which are used in this capacity in urban environments has long surprise nobody. There are several reasons, and home - a large mass, which causes strengthening walls, foundations, use heavy lifting equipment, etc. Recently, however, the tree in this area is already a worthy competitor - light steel structures, and no longer only imports but also domestic. Taking into account our mentality, but we can assume that the rafters of solid wood will go down in history not soon. It seems that as a competitor to the most prospects for laminated veneer lumber. It's very expensive stuff, but he has strength of metal and wood easily. A beam of it suitable for covering a very wide openings. In conclusion, we say that the "feet" for the roof can be installed on site (this is still more common) and use the ready - the factory. The second option has its advantages, in particular, higher dimensional accuracy of the rafters and other elements of the system. In this case, there is no need to fit - "legs" is guaranteed to stand up for their assigned seats. Prefabrication also implies a stronger version of combining the elements of truss system, and hence increases the reliability of the roof, and increases longevity.