Metal Roofing Types, Installation and Operation Part 3

Varieties of Polymer Coating of Galvanized Roofing Steel

Polymer coatings for galvanized steel roofing are primarily distinguished by different resistance to ultraviolet radiation (colorfastness), temperature (heat resistance), aggressive environments, mechanical damage, and other factors.

The technology for the production of metal-plastic roofing sheets is quite simple. A thin and loose special layer is chemically applied to zinc on both sides, providing a stable connection of the primer and the base. A polymer layer is applied over the primer, and protective paint is applied on the reverse side. In a multilayer material, which is a metal plastic, the strength and ductility of galvanized steel are combined with corrosion resistance and the beautiful appearance of a polymer coating. Metal-plastic roofing materials do not need to be painted for a long time, and operating costs are practically reduced to zero.

The acrylic coating of galvanized steel has several disadvantages. Acrylic is an unstable paint layer, it is easy to damage, fades in the sun, the average corrosion resistance is 2-3 years, then it begins to peel off.

Aluminum Seam Roof: The Benefits of Aluminum Roofing

The aluminum rebate roof is made from coated rolled metal. Lightweight (about 2 kg / m2) allows it to be used on almost all roof battens. The advantages of aluminum seam roofs are its durability, colorfastness, corrosion resistance. Unlike other roofing materials, which are attached to the base with self-tapping screws, pins, and other devices that penetrate the coating, the aluminum roof, when using folding and clamps, is laid without a single hole in the roof.

The service life of a roof made of aluminum sheets is not less than a roof made of copper, i.e. 100-150 years. She does not require leaving. And its cost in comparison with a copper roof or a roof from titanium-zinc is much less.

The aluminum roof can be made in almost any color due to special anodizing. This is very attractive to the customer. The fact is that visually the roof is equal to one-third of the volume of the house as a whole. Being interesting in shape and color, the roof can meet the requirements of modern design, play an important role in the design of the appearance of the house.

Almost always, the roof requires a waterproofing layer. Only a soft roof does not require a waterproofing layer since it forms a continuous sealed surface. When using other roofing materials, a waterproofing layer is necessary.

Metal Roof Defects and Coating Repair

The new iron roof has practically no flaws, but wet spots may appear inside the room at the junction of the wall. Most likely, the ceiling has poor thermal insulation, so warm air, always trending upward, seeps out of the living room. And due to the fact that the attic space is poorly ventilated, it settles on the lower surface of the roofing iron in the form of condensate, which, flowing down, falls onto the Mauerlat and through it onto the wall. To eliminate this defect of a metal roof, it is necessary to make ventilation of the attic. There are times when the dormer is boarded up, from which the walls also begin to get wet.

The leakage of metal roofs in the year of manufacture or the next year after repair can occur due to the fact that the folds (standing or lying) are either loosely crimped or were not coated with putty on the iron mark or lead whitewash. The following materials are used as sealing materials in the repair of metal roofs: one-component silicone sealant “Elastosil 11-06”, thiol mastic KB-0.5; self-adhesive tape “Galen-D”. You can use a sealing laminate – Armrovel, consisting of a reinforcing base (fiberglass type T-12-41, ASTT) and mastic Roofing. The sealant with a layer thickness of 2 mm should be applied to a dry, dust-free, peeled off the dust-free surface of the rebate with a spatula until a smooth surface of the sealant layer is obtained.

Sometimes it is necessary to remove holes and fistulas in the mating places of the roof with the supporting parts of the protruding structures. Sealing of folds and holes of a metal roof is performed at a relative humidity of not higher than 75% only on a dry, cleaned, dust-free surface. To repair a metal roof with their own hands, a self-adhesive tape “Gerlen-D” is cut into strips 25-30 mm wide and a length equal to the length of the sealing folds, but not more than 2.5-3 m. Put strips of tape on the folds, press them firmly with a rubber roller. Large holes, holes with a size of 10 mm or more are covered with a patch of roofing steel or two layers of fiberglass on the sealant.

Painting and Protection of a Metal Roof

Painting of metal roofs must be done every 3-5 years. The roof of a steel sheet is especially in need of regular painting (galvanizing does not require special care for the first 10 years, and then it also needs to be painted every 3-5 years).

The composition for the protection of metal roofs “Zinga” provides a barrier (passive) surface protection, primarily from penetrating moisture.

A layer of zinc on a metal surface actively protects iron from corrosion – it oxidizes itself, preventing rust (the so-called cathodic or donor protection). It is the combination of these key factors that distinguish Zinga from paints in general and from zinc-containing paints in particular. The latter create, first of all, a barrier (passive) protection, the effect of which is enhanced by the inclusion in the paint of a different amount of zinc particles (of various sizes and purities).

The metal roof must be properly looked after. During the operation of wooden supporting structures, bolts, clamps, and other metal fasteners in the corner joints should be tightened and, if necessary, damage and decaying individual elements should be replaced.

Roof areas with a damaged paint layer must be painted immediately, without waiting for the next general painting. If corrosion occurs on roofs and gutters made of galvanized steel, they must be coated with anticorrosive compounds. Sealing of faulty lying and standing folds of sheet steel roofs should be done with their preliminary lubrication with sealant or surgical putty.

Replaceable damaged elements or individual sections of the roof from piece materials should be laid on a continuous crate along with a layer of rolled material (roofing felts, glassine, roofing felt, etc.). In roofs of piece materials with the significant blowing of snow into the attic, the joints between the elements of the roofing must be coated with cement mortar.

Failures of the external drainage system (pollution and destruction of gutters and drainpipes, violation of the interface between individual elements and the roof, icing of drainage devices and overhangs) should be eliminated as defects are detected, avoiding deterioration of the system. Roofs with external drainage should be periodically cleared of snow, preventing its accumulation with a layer of more than 30 cm. On roofs with a slope of 45 ° or more and with the free discharge of water, snow should be cleaned only in grooves and above the eaves.

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