The name Seam roofs, perhaps, will not tell you anything sensible. Well, we met somewhere somehow once by mistake. But in fact, you can’t even imagine what a sheet roofing, seam roofing is! It’s simple: it is the most convenient and most efficient ROOF to use. Seamed roofs are called roofs made of sheet and rolled galvanized steel (both with and without polymer coating), as well as roofs made of non-ferrous metals. Seamed roofs are metal roofs in which the connections of individual elements of the coating (pictures) are made using seams.
A picture is a roofing element with edges prepared for seam joints. Seam (folded joint) is a type of seam formed when joining sheets of metal roofing. Distinguish between lying and standing seam connections, single and double. The side long edges of the steel strips running along the slope are connected with standing seams, and the horizontal ones – with recumbent seams. Folds are made (rolled), either manually with a special tool, or in a modern way – with special electromechanical seaming devices. Nowadays, there is another type of folds – self-locking. They are connected to each other without using a tool
The most airtight and moisture-proof is a double standing seam – this is a longitudinal joint protruding above the roof plane between two adjacent roofing patterns, the edges of which have a double fold. Today, seamed roofs in Western countries are mainly performed using a double standing seam. In Russia, leading firms using Western equipment have also switched to this type of roofing pattern joining. And today a large number of companies have appeared on the construction market offering roofing using modern technologies. Unfortunately, it is not easy to check whether they are really up-to-date using advertising brochures. The complexity of the roofing structure lies in the high percentage of hidden work, errors in which appear only during the operation of the roof. There are known examples when, during the construction of roofs, the lack of professionalism of the performers led to the need for a complete replacement of the roofing.
When installing roofs using modern (roll) technology, it is very important to correctly execute the abutments. Unfortunately, to date, the developed types of nodes are clearly not enough, especially for reconstructed buildings in historical buildings. Therefore, the experience of specialized construction organizations that have been working on roll technology for a long time and have their own technical developments, competent highly qualified specialists is invaluable, which gives them the opportunity to perform roofing work with high quality. Often, such firms, having a database of various design solutions, can provide qualified assistance to both their partners and designers..
There are a number of indicators by which it is possible to determine to what extent this company can be entrusted with the difficult task of roofing. First of all, this is the presence of a license, a registered trademark, patents, letters of recommendation from customers and photographs of completed objects. The guarantee of the firm’s reliability is both a guarantee for work and penalties for marriage and for failure to complete the work. The customer needs to make sure in advance that there are certificates for the materials that will be used in the work, their absence can lead to large losses. If all of the above documents are available, then this is already a good basis for starting cooperation..
Seam roof device
One of them is a staircase, consisting of simple wedge-shaped steps, which rest with their wide end on the surrounding walls, and with their narrow end on the middle support pillar. Another option is that individual steps protrude in a cantilever manner from the middle monolithic support pillar. Such a staircase can be located far from the walls (even in the middle of the room). The third type differs from the previous ones in the absence of an internal support column. The steps are simply embedded in a curved (concave) wall.
The recommended roof slope when using folding technologies is more than 140. For lower roof slopes (from 70 to 140), a solid foundation is mandatory, as well as the use of a double fold, sealed with silicone sealant.
Violation of the required parameters leads to the formation of condensation on the inner side of the sheets, which can also cause premature corrosion. The connecting parts used, such as nails, bolts, wires, clamps, must be made of galvanized steel. This is to ensure that they have the same lifespan as the top coat. Today, the traditional technology of installing folded metal sheet roofs (using special hammers) is being replaced by a new, modern technology of installing rolled metal roofs (using a power tool), which improves the quality of the seams and significantly increases the productivity of roofers. Let’s take a closer look at these two technologies..
Traditional technology roofing devices made of sheet steel, requires high qualifications of roofers. The work is carried out in several stages. The first stage: production of paintings for ordinary roofing of roof slopes, eaves, wall gutters, gutters. For the preparation of paintings, in the beginning, blanks of the required shapes and sizes are made right at the construction site (according to the drawings of the future roof). Steel sheets are marked on parts using measuring instruments and tools, marks are applied to the metal. Then the steel sheet, depending on the thickness, is cut with various types of scissors and connected with a recumbent fold into pictures, a slope length, the side edges are bent, i.e. make blanks for making standing seams.
Second phase: the paintings are raised to the roof and their sides are connected to each other with a standing seam (most often single). Then the paintings are attached to the lathing with narrow steel strips – clamps, which at one end are brought into standing folds when they are bent, and with the other they are attached to the lathing bar. Thus, a high-quality roof covering is obtained, without any technological holes. Openings at chimney and gas pipes, including ventilation ones, are covered with aprons made of galvanized steel.
Galvanized roofs cannot be painted with ordinary enamels, nitro and oil paints. For this purpose, there are special paints, however, they are very expensive (about $ 1 / m2).
Roll technology so called because roofing pictures are made directly on construction sites from metal delivered in rolls and can be of almost any length. This is what allows you to avoid transverse (recumbent) folds and, accordingly, the main places of leaks. Roofing pictures are usually joined in a double standing seam. To ensure complete impermeability of the joints, as mentioned above, the fold can be sealed with silicone sealant. To use roll-to-roll technology, modern equipment is required, including machines for cutting metal, special bending and seaming machines, etc. Roll-to-roll technology is the most progressive and makes it possible to arrange modern seam roofs both from simple galvanized rolled steel, and from galvanized steel with polymer coatings.
The advantage of roll-to-roll technology is:
More than 50 years ago, the so-called corrugated bitumen sheets began to be used as a roofing material, which are now represented on the Russian market by ONDULIN (France) and BITUWELL (Germany). This material is made from bitumen-impregnated cardboard. On the front side, the sheets are covered with one or two protective and decorative paint layers. The color range of this material is not inferior in its variety to other coatings: you can choose shades from red to green.
Such a roof has sufficient rigidity and is lightweight (one sheet – about 6 kg). This allows the batulin sheets to be mounted on the old roof. They are easily attached to the lathing (using nails), their installation does not require professional skills and special equipment. The service life of corrugated bituminous sheets is about 50 years, the cost is about 4.5 USD. per sq.m.
Outwardly, this material resembles an asbestos-cement roof – slate, which has not been produced in Europe for a long time. It is believed that asbestos, which is part of the slate, is an environmentally harmful material..
In Russia, asbestos cement is not prohibited. And 24 enterprises producing asbestos-cement products continue to operate in our country. Currently, slate is produced in various colors: red-brick, yellow, blue. The paint forms a protective layer that protects the sheet from destruction (reduces water absorption and increases frost resistance). In addition, the volume of asbestos emissions into the atmosphere decreases, and the service life of the material increases by 1.5 times (in general, about 50 years). By weight, slate is heavier than ondulin (10 -14 kg – 1 meter), but it is much cheaper: only 32 rubles per sheet.
Today slate of three modifications is produced:
This roofing material is still very popular in Russia. But the asbestos-free cement-fiber slate, which is presented on the market by the German company ETERNIT, has not yet found wide application among our compatriots. Obviously due to the high cost. However, everyone has the right to choose what he likes best. And there is plenty to choose from.
They start with blank sheets. The roof is wiped dry from grease, cleaned of rust and covered on both sides with hot linseed oil twice. The grease is removed with a cloth soaked in gasoline, and the drying oil is applied with the addition of a dye so that gaps are noticeable. Folds are folded along all the edges of the sheets, then the sheets on the short sides are connected with recumbent folds into pictures. The minimum picture consists of two sheets. With a small slope height, you can prepare a picture with a length for the entire slope and connect the long sides with a standing seam on the roof.
The sheets are fastened to the crate with clamps, which are nailed to the crate with one end, and the other are sealed in standing folds. The distance between the cleats is 500-700 mm. They are cut from galvanized roofing steel in the form of strips 30-40 mm wide and 100-150 mm long and twisted at an angle of 90 °.
The eaves edge of the roof is held by T-shaped crutches nailed along the edge of the eaves every 700 mm. You can use rectangular metal strips 3-4 mm thick and 40-60 mm wide, nailing them every 300-400 mm.
The most difficult section of a steel roof is the collar around the chimney. It is better to make it in advance – all work can be done below, on the workbench, and the roofing sheet with a ready-made collar can be included in the general covering. Roofs made of non-galvanized steel should be primed and painted (at least twice) immediately after installation. For oil paints (including when using red lead iron), linseed oil with the addition of pigments serves as a primer, for nitro enamels – a nitro primer.
Sheet roof maintenance
The applied paint protects the roof from rapid destruction. But it also over time (rather quickly) collapses under the influence of the joint influence of water, air, dust, sand, smoke, sun on it. Thus, carbon dioxide contained in the air, combining with moisture, accelerates the destruction of paint. Hydrogen sulphide in most cases discolors some paints and also adversely affects the paint layer. Dust and sand carried by the wind are most often mechanically affected, abrading the paint over time. Smoke mainly contaminates painted surfaces. When cleaning the roof from dirt, the paint layer is additionally damaged from rubbing on it with a broom, especially hard. In addition, the paint will fade when exposed to sunlight, so it is advisable to use lightfast paint.
The surfaces of the roof should be painted smoothly, then they will not retain dust and sand. The loss of elasticity by a layer of paint may result from the poor quality of the material, uneven application of layers of paint, the use of coarse-ground pigments mixed with drying oil. Some developers, who do not have thick paint, prepare themselves by mixing dry paint-pigments with drying oil. The result is one of the most substandard paints. Bubbles appear on the surface to be painted if the paint is applied to an insufficiently dried or poorly cleaned surface from dirt and soot, to a wet primer and putty. The uneven thickness of the paint layer leads to the formation of cracks, since thin layers dry faster than thick ones. Correctly applied oil paint, prepared with good drying oil, has a shiny surface after drying. As the paint degrades, its gloss gradually loses, it cracks and lags behind the base.
In addition, the steel roof, when heated under the influence of the sun’s rays, expands and tears the old paint that has lost its elasticity. This is because the steel expands more than the dried paint layer, resulting in a mass of fine cracks on the surface. Water gets into cracks, steel starts to rust and a new paint is required.
Correct and durable painting of the roof is done in three, at least two times. Dyeing in one go will give poor results and ultimately only lead to waste of materials.
The roof must be carefully prepared for painting, since a more reliable adhesion of the paint is ensured with a properly prepared surface. The preparation process includes cleaning the roof from dust, dirt and rust, first with a hard and then with a soft broom or brush. Rusty spots are cleaned with steel brushes, dust is swept away and painted immediately. After that, it is checked for cracks and punched places on the roof, which are often formed when cleaning snow with steel shovels. It is best to inspect the roof on a sunny day, when even the smallest holes are clearly visible. The inspection is carried out by two people – one with a long stick is in the attic, the other with a piece of chalk on the roof. Having found the hole, the one in the attic knocks on it with a stick, and the one on the roof, finding the hole, draws around it with chalk. And only after completing these works, they begin to eliminate defects.
Roof repairs begin with filling the holes on the ridges, carefully smoothing them with a knife. The putty is prepared on dry chalk, sifted through a fine sieve, and on natural drying oil. Such a putty is strong, elastic, adheres well to the surface and smoothes, dries, well, it cracks. Of course, this putty can also be used to cover small holes in the roof plane. Sometimes it is smeared with a thin layer on the roof, a patch of fabric is laid and painted over after drying.
The holes on the roof are sealed by applying patches that are cut from tarpaulin, thick burlap or fabric. The size of the patches depends on the area of the repaired area. Then a liquid oil paint is prepared from thick-grated iron or lead red lead on natural drying oil and the cut patches are soaked in it, keeping them in the paint for 10 – 15 minutes. The patches must be completely dry when dipped in paint. Having taken out the paint, the patches are squeezed out of its surplus, applied to the previously painted areas, carefully smoothing it with your hands or with a hard brush. Smooth the edges especially carefully. After 5 – 7 days, the pasted patches will dry out, and you can start painting. It is necessary to paint in dry weather. If the cleaned roof has stood for two weeks or more before staining, then it is swept with a brush.
When painting the roof for the first time, the paint should be thinner than the next. Therefore, for the first painting, 0.6 – 0.7 kg of drying oil is taken per 1 kg of thickly grated paint.
Liquid paint adheres better to the roof and penetrates into all pores. For the second and subsequent painting, 0.4 – 0.5 kg of drying oil is taken for 1 kg of thickly grated paint. To dye 1 m2 of roofing, an average of 180 – 200 g of ocher, 70 – 90 g of mummy, 35 – 40 g of red lead, 250 – 280 g of copperhead is required. Copperhead is the most durable in terms of service life.
After 5 – 7 days after the first painting, the roof is painted a second time, after which, after 5 – 10 days, paint is applied for the third time. Oil paint dries completely on average after only 10 days. Compliance with the paint drying regime improves the quality of work. The existing practice of painting the second time in 1 – 2 days after the first ns will give high quality. The technique for painting the roof is the same as for painting walls and ceilings. With normal pressure on a brush weighing 400 g, one brush can paint 600 – 800 m2 of the roof. The brush wears out less on the new roof than on the old.
When painting, the paint is shaded along the slope. First of all, the roof descent is painted, and then work continues from the ridge to the descents. Paint a little on the brush and shade it with a thin layer without rough streaks and streaks. Over time, cracks appear in thick layers of paint, in which water will linger, destroying the roof. You should work on the roof in felt boots or ordinary shoes, but with felt soles tied, which do not slip on steel and do not destroy the newly applied paint layer.
If the roof does not have fencing gratings, it is necessary to tie a rope to the rafters, battens or beams, but not to the stove and other pipes. Downpipes are painted in the same way. To make the pipes last longer, they are dismantled from the outside before being painted, cleaned of dust, dirt, especially inside. The inner surface is painted one or two or three times simultaneously with the outer surface and only then the pipe is installed in its place and securely fixed.
Steel roofing rusts not only from the outside, but also from the inside, those. from the attic. This usually happens between the battens. The part of the roof that lies on the crate does not rust, as it is protected by wood (boards). Rusting occurs due to the fact that warm air passes through the ceilings into the attic. It is known from practice that it is often between the crate that there are rusted places, but sometimes they are also under the crate. To protect the roof from rusting, the steel between the battens should be cleaned of rust with a hard brush or soft steel brush and painted once or, better, twice. This will extend the life of the steel roof. If the galvanized roofing steel coatings begin to rust, then without wasting time, the rust is removed, the cleaned places are primed with liquid paint and painted twice.