Mild Steel
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Defect and Repair
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Mild Steel (Infill Panels) |
Defect
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Repair
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Chip Off of Paint
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The defective panel should be brought to a good state of repair before repainting is done. The original coating that has low adhesion to the substrate should be removed using a sharpened paint scrapper or hydoblasting technique.
Paint is then applied over the substrate evenly with particular attention given to achieving a good standard of finish. |
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Buckling, Deflection and Warping
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The defective panels should be replaced preferably with panels that have a solid backing. The positioning of the anchors/ bolts/ fixings should also be reassessed to allow for greater differential movement. |
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Fungal Growth
Fungal growth, can occur on virtually all surfaces when the “micro-environment” on and around a particular installation is conducive to it. In general, it is believed that fungi can grow as a result of suitable conditions, such as the presence of fungal spores, moisture and nutrients from “dirt” of various types.
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If fungus is suspected, it is recommended that a spot test with sodium hypochlorite solution be carried out for identification purposes. The most convenient source of sodium hypochlorite is household bleach. The bleach should be as fresh as possible and the hypochlorite/available chlorine concentration should preferably be above 3%. Care should be taken in handling the solution (i.e. wear the appropriate safey equipment-safety glasses, protective gloves etc), which is quite alkaline. Any tested areas should be thoroughly rinsed with fresh water afterwards.
The test procedure is to apply a drop of the bleach solution to a suspected area, mark the extent of the drop (unobtrusively) and wait a few minutes. If fungus is present, the dark material will be destroyed by the bleach and a clean drop area will result. Please note this is not a foolproof test for identifying fungus as the bleach can also affect organisms such as algae and bleachable organic matter. However, it is a valuable test as it will distinguish between fungus and normal inorganic dirt, which will not be bleached. |
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Lichen
Lichen is a growth incorporating both fungus and algae. Its appearance on a prepainted roof, as illustrated, is quite distinctive.
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Note: For more defects, please refer to the Defect Library.