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Believe it or not metal sheets are everywhere. Probably you do not normally think of noticing residential or production industry roofs, but if you’re driving in any areas you will probably find a factory or building covered with colored sheet roof. However, how much do you know about colored sheets? Do you have enough information about their look and style, repair and maintenance, installation procedure, durability and the type of colored roof sheets?
It might be easier to make up your mind about this kind of roofing type by considering the basic description and their pros and cons. In the past the surface of the sheet was coated with oil to prevent the metal from corrosion and rust and to protect it during deformation as well. However today because of problems with using oil including financial problems, environmental issues and lack of durability of the desired material for a long time, this method has lost its importance. More modern technologies such as production of pre-colored sheets have been replaced with the previous methods too. Colored or pre-colored sheets are the result of the coloring operation in a constant process. The production of colored sheet is a constant, fully automatic process in the surface of aluminum coils for coating in which the surface of the sheet after visual inspection will go through preparation operation then coloring procedure. Metal colored sheets can be applied in the following areas:
One of the factors considering colored sheet installation as roofing is the insulation beneath it, because colored sheets by nature have high coefficient of heat conductivity and this feature results in using insulation for condensation control. Insulation beneath colored sheets itself causes insulation loss and appearance of mold due to high absorption of water and insulation damping in the long run and it will cause reduction of thermal efficiency at last.
The coefficient of expansion and contraction in metals is high and so is the colored sheet. therefore, due to the expansion and contraction of the screw and colored sheet in heat and cold conditions, the need for tightening the screws will be increased. Tightening of screws is necessary for repairing and maintenance of the colored roofing sheets and because of the possibility of screws to get loose during expansion and contraction, sealing the structure will be difficult. Color sheets are versatile in design and color and because of this feature construction companies have a lot of options to choose from. However, the sheet color is polyester therefore they won’t have enough UV resistance and their color will fade over time.
One of the advantages of colored sheets in roofing is that they can be sold again as second-hand sheets. Moreover, they can be used as recyclable sheets. This feature is rarely true about other roofing materials. The overlapping degree for colored sheets compared with other roofing materials is less and makes it easier to install. For example, Onduvilla roofing material is installed at close distance and has higher cost of substructure compared with color sheets. They also use more screws for installing Onduvilla. Therefore, color sheets are more economically efficient in this case compared with other roofing materials.
In manufacturing industries where they have more exposure to corrosive gases during the production process, colored sheets cannot be a good choice, because of their reaction with corrosive gases. This feature causes corrosion and rusting in the roof. Then it`s better to use materials that do not react with acid and base. Overlapping degree in metal colored sheets varies in different formats. Besides, purlin distance should be considered according to the type and format of the sheet. For example, for colored corrugated sheet the purlin distance of 60 c.m is suitable and for sealing two corrugated waves should be considered. Alongside with color sheets a more modern material called UPVC has been introduced to the roofing industry aimed at getting rid of the negative features of colored sheets. Compared with metal color sheets, UPVC sheets have lower coefficient of heat conductivity that is 0.325 which is 2000 times less than metal sheets and this feature leads to energy optimization in manufacturing industries. As long as the surface of UPVC does not heat up easily and the transfer of heat is gradual, therefore UPVC sheets are better alternatives for manufacturing sheds that energy saving is of high importance for them.
Because the surface of UPVC sheet does not heat up as fast as metal colored sheets and heat transfer is slow, therefore for manufacturing sheds in which energy saving is important UPVC sheets are more suitable options than metal colored sheets. UPVC sheets are more color stable compared with metal colored sheets due to having alloy polymer on them with high UV resistance and also for not getting detached from the surface of the sheet. UPVC sheets do not react with corrosive gases. These sheets by nature are not reactive at metal therefore they can be a better alternative for colored sheets in industries such as steel, raisin, poultry farms, fertilizers, salt and etc.
The degree of impact resistance for these sheets is high so that a sheet with thickness of 2 m.m can bear the load in scattered manner. With UPVC roofing sheets are installed in line with substructure with appropriate thickness, they will remain on the roof without any problems. The installation procedure for UPVC roofing should be followed correctly. Compared with metal colored sheets more screws are needed for UPVC roofs installation at least 5 for each square meter. Furthermore, all waves should be screwed and this makes the installation procedure more different compared with metal colored sheets and should be done with more care.
Another issue that should be taken into account about UPVC roofing sheets is the expansion and contraction coefficient. The coefficient of expansion and contraction in UPVC is very low, whereas this rate for metal screws is very high and this causes the screw to put pressure on UPVC sheets to open up space and make them crack. Consequently, it is recommended to use corpies to prevent this from happening.
The degree of curving in UPVC sheets is different from metal sheets. Metal sheets have more curving ability compared with UPVC sheets and their impact resistance prevents them from breaking. Whereas UPVC sheets can be curved 20c.m in each meter and in case that pressure more than their resistance puts on them they will break. Therefore, these two materials are different in this matter and curving degree should be considered in installation.
Although colored sheets may be a good choice for some factory owners, we know that they are not always the best option for every customer.