In the industrial and civil construction practice of placement flat roofs, including a variety of private porches, commercial and ancillary buildings is common. The main functions of the flat roof, like any other, are the protection of building from rain and heat insulation. In addition, many flat roofs are provided to place sports ground, garden, terrace of house or public building, solarium.
Technology of installation of flat roofs with wooden frame has its own characteristics, so it deserves a detailed story.
INSTALLATION OF TOWERS
The beams are usually the towers for hard flooring of flat roofs. They are placed at intervals of 40, 45 or 60 cm (between the center lines). When spans are over 2.5 meters there is a need for diagonal or other connection stiffness to prevent deformation of the beams. Beams can be attached to roof beam or load-bearing walls or, in the case of extensions, can be hung on steel clamps (brackets) or fix in tank of common walls.
FORMATION OF INCLINATION
The slope of flat roof must match the ratio of 1:80 for smooth cover and 1:60 for cover with a rough surface. This inclination is required to remove the water. If it is insufficient, the puddles will be formed. Thermal transfers of flooring can lead to the rupture of surface and the water from these puddles will leak inside.
There are several ways to form the needed slope, for instance, by hammering tapered rails of crate to the upper surface of beams. You can also make a crate from nailed to the beams rails, the height of which gradually decreases in the direction of inclination. Another way is laying crate with wedge-shaped rails across the beams. Last of the following options provides improved ventilation. Slats of base flooring nailed across crate also improve the roof ventilation with internal insulation.
In order to put roof properly, we need flat basis. For this purpose thermo- and waterproof plywood or other kind of artificial materials for external use of wood are exploited. Old flat roofs were usually covered with matched boards (lining) of coniferous wood. Panels or sheets (usually 18 mm thick) are put across the beams with long side. Their ends are placed for towers in the middle of the beam along its thickness. These compounds should diverge from each other. Between the beams bolts or spacer elements for additional towers for long sides of the sheet can be installed (the need for their presence is determined by the thickness of the material and length of span). Coverage of rolled roofing materials should be started with investing leveling flooring (flat sheets). These sheets are put with temperature gaps (3 mm) and fixed with the help of nails or screws. If you can not immediately cover flooring roofing material, it must be temporarily pressurized by filling the cracks with mastic of cold hardening and sealing seams with waterproofing tape for roofing.
LAYING LEVELING FLOORING
Any type of flooring should be pressurized with either bitumen or with two or three layers of roll roofing material. To flip the sun's heat a roof can be coated with special paint or layer of stone chips 12 mm thick.
COVERING FLAT ROOFS
To cover flat roofs materials that can hold a continuous carpet are required - these are, in particular, bitumen, bitumen-polymer and polymer materials, including rolled and mastic. Carpeting should be flexible enough to withstand the temperature and mechanical deformation of basics of roof. In contrast to the pitched roofs, for covering flat roofs artificial and sheet materials are not used.
Bituminous mastic - waterproof material made from natural or synthetic bitumen. This material has high weather resistance. It is melted in an open pot and put on the roof in hot condition. After congealing it forms a waterproof carpet. With a special leveling two layers with thickness of about 18 mm are formed on a bed of rolled roofing material that covers the flooring. Note that insertion of bitumen - work that can only be performed adequately by qualified professionals.
ROLL ROOFING MATERIALS
Rolled material impregnated with bitumen, is put as layers to form a multilayer or composite roof, glued cold or hot bitumen. Manufacturers offer several types of such materials. Selection is carried out, taking into account their financial capabilities and the required level of durability of the roof.
Traditional rolled material is not as tough as modern coatings with improved basis with fiberglass, polyester fiber or fabric. Sometimes modified bitumen with high plasticity is used. Roof coverings with such materials (they are put on the cold bitumen mastic) should be entrusted qualified professionals. It is easier to use modern adhesive materials that are covered with two layers.
Roofs with butyl and EPDM (ethylene-propylene-diene membrane) - a flexible single-layer coating, which are put on the top and nailed to the base layer of roll roofing material. They are simple in investing, form a solid coating that does not require special care. This roof is made on request and delivered as a single carpet to the underside of which the mounting valves are welded so the intermediate fastening nails does not violate the integrity of the coating. Manufacturers offer a variety of accessories, including corner section and Pipe coupling for sealing flue pipes and vents. They are attached with the help of mastic tape.
ADJUNCTIONS AND PARAPETS
In those places where the flat roof adjoins to the wall, you leaks may happen. Therefore roofing is usually wrapped up against the wall, forming a side or apron that covered mortar of masonry, or drain. Parapet walls are usually end with canopy which visor should cover the side of the wall from rain. In this solution under a canopy waterproofing seal of bitumen, lead or roll roofing material is put. Parapet wall, not exceeding 35 cm, can be equipped with bitumen apron that goes up and comes under the canopy, forming a moisture barrier (MB). Alternatively barrier is formed with roofing, raised along the wall only two rows of masonry and attached it to this level. Often plastic MB (such as lead or high-quality rolled roofing material) is laid a seam in the stack to the roof and then lowered, creating a drain on the apron. High hollow wall needs tray moisture barrier to prevent water infiltration and drainage into the cavity. Tray MB is formed with the help of lifting from the inner to the outer wall on one row up. Facing parapet with concrete is not exactly a satisfactory solution, because shrinkage of walls can cause cracks.
NEW SPOUTING CHUTE
So, hollow wall, to which adjoins roof extension, you need spouting chute to be protected from moisture. It is usually embedded in the construction of the wall, but in the case of new additions to the house it is possible to insert special polypropylene spouting chute in a wall by removing the outside row of bricks.
Technology of installation trays is the following. First you need to remove the three bricks from the third row above the planned level of the roof. It must be run with caution, being careful that the wreckage doesn’t getting inside. Then you need clear cavity bricks, put a strip of lead discharge of such width that it entered into wall at 50 millimeters and that when bending down it shuts off the apron roof by 75 millimeters. Then you press the drain with first element of the tray by inserting it into one of the ends of the hole. After this, put in the tray two bricks with mortar, fill the top with pieces of slate and cover with a solution. Drain port must be held at the base of the seam between two bricks to drain moisture from the cavity. You should also cut two bricks, leaving thus opening still three bricks. Aligning the drain, insert a second section of the tray and connect the two sections of the special plate, setting it on the edge of the abutment to seal the connection. The next step should be to put into the hole two more bricks and continue in the same manner until the width of the tray will not be sufficient to protect the new extension. It should also be remembered that to install the last section of the tray it is enough to remove only one brick at the end. When the solution solidifies, you need to embroider the seams to meet new masonry old.
OPTIONS OF FLAT ROOFS
Flat roofs are arranged as in the form of attic and without (combined coverage). Flat roof with attic usually does not require mechanical removal of snow. Melting snow during the winter occurs due to heat generated from the roof space, and by the power the wind. Mechanical clearing of snow may be required after heavy snowfall, and if the surface of the roof is operated during this period. The disadvantage of flat roofs with attic is the inability to regularly monitor the humidity as insulation and sealing waterproof carpet. About the damage to the carpet will be known only after the appearance of leaks in the ceiling. To make a flat roof with attic, of course, you have to spend more money than for the roof of the same area without attic. At the same time the roof with the attic has a number of advantages, namely: - attic, even low, allows you regularly monitor the tightness waterproof carpet; - attic makes it possible to monitor humidity of insulation and if necessary to carry out its drying, e.g. by ventilation (opening hearing windows); - attic divides roof structure, and therefore the estimated difference of external and internal temperatures in two. Reducing the air temperature difference to both sides of structures (attic floor and flat roof), improves their operational temperature and humidity conditions, and contributes to their functionality for a long time.
INTERESTING TO KNOW
Exploited flat roofs
The popularity of exploited flat roofs around the world is growing every year. Particularly relevant is the question of efficient use of available roof space in large cities, where the cost per square meter of land is very high. Operated roofs are usually used to organize outdoor cafes, gardens, pedestrian zones, etc. At the same time, due to lack of green ground placing gardens on rooftops, terraces become an important compositional element not only of space-planning, but also the urban structure.
The concept of creating roofs, which are used not only for the primary purpose relates to the cottage and the adjoining building. Such roofs are the perfect place to relax, because here it is possible to locate ornamental landscape planting. Exploited roof surface is provided for placing porches, greenhouses, and for other purposes.
Variety of exploited roofs
By functionality several types of exploited roofs are distinguished: - coverage with limited ability to move (gravel embankment); - pedestrian coverage; - so-called green roof or roof-garden. Particular attention should be paid to the green roof.
In appearance and purpose of green roofs can be divided into several types: - intensive landscaping (similar to gardens and parks); - with minor landscaping (no trees and tall shrubs); - with grass (minimal layer of soil is sufficient, but the movement is only possible with special tracks).
You cannot avoid another classification. Depending on the location of the insulation layer (above or below the waterproofing layer) are two variants of operated roof design: the traditional and inversion. Most vulnerable place of traditional roofing waterproofing is the top layer that is sensitive to impact of adverse factors such as ultraviolet radiation, temperature and so on. The principle used in stripping roofs, is to protect the waterproofing layer from adverse thermal and mechanical stress by layer of insulation, which lies above the waterproofing. When using this structural solution to roof waterproofing layer regardless of the season will be in a practically stable temperature close to the temperature inside the building.
THERMAL INSULATION OF EXPLOITED ROOFS
Placing of the exploited roof is a complex engineering problem that needs solving in the strict adherence to a number of requirements set for modern high-tech roofing, as well as compliance with hydro, steam and thermal insulation. On roofs that are subject to exploitation, as in the roofs generally, insulating layer should meet the requirements set for the envelope building However, note that the very high demands are made to the used insulating materials. Here is a list of requirements to be met by modern insulating materials used in the construction of inversion roofs: - high thermal insulation resistance (low thermal conductivity); - minimal water absorption; - low flammability; - high compressive resistance; - invariance of geometric dimensions; - simplicity of working with material. Necessity of using the materials with high moisture resistance and low water absorption is caused mainly by the fact that the penetration of water vapor into insulation structure, repeated cycles of freezing-thawing eventually lead to loss of insulating properties, or even to the destruction of the material. Repair of the roof will require significant resources and cause many inconveniences. Therefore for placing exploited roof you need the following technical solutions and materials that provide maximum possible term operation without repair roof (25 years and over). Mentioned above requirements are consistent with extruded polystyrene of domestic and foreign production. Use of such materials reduces energy costs, increase comfort, reduce adverse environmental impact, and protect structures from damage caused by temperature changes. It should also be noted that when constructing a green roof system it is necessary to create watering system and removal of excess moisture (drainage system). The requirement of the simultaneous presence of these two systems is caused by necessity regardless of external environmental (weather) conditions to maintain constant soil moisture levels. The system of sewerage should provide formation, collection and removal flows formed by rainfall, snowmelt, and water, which watered the plants. You must take into account area of the exploited surface, the existing incline surface, the presence of vegetation, soil type and other factors.