How to maintain a metal roof
Roofs endure harsh weather and are subjected to greater strain than walls. Debris from the surrounding nature, such as dust, sap, spores, cones, branches and ash, accumulates on roofs. A well-designed and installed metal roof is cleaned of this debris by gravity. However, a roof is not always ideal in terms of cleaning, in which case snow, ice and water cannot slide off the roof on their own. Dents and scratches that shorten the roof’s service life may have been left behind after installation or snow removal. Therefore, the roof should be inspected and maintained from time to time.
Initial inspection of a new roof
The most important thing is to inspect the roof carefully immediately after installation. Any dents and scratches must be repaired immediately. They are cleaned lightly with a wire brush and painted according to the sheet metal supplier’s instructions. Spray paints must not be used.
It is also important to check that there are enough fasteners, as this ensures the roof’s resistance to storms. There must be enough screws particularly at the eaves, ridge and near the longitudinal seams. There can be plenty of screws in a profiled roofing sheet, such as a tile-patterned sheet, because its thermal expansion does not cause problems. The concealed fastening of the standing seam roof that is popular today cannot be inspected, so one simply has to rely on the quality of the installer’s work.
When checking the fasteners, also make sure that all fasteners comply with regulations and are of high quality. Also check that all roofing screws and roof safety fasteners have washers, that is, sealing washers, so that the roof is watertight. Unfortunately, there are plenty of non-compliant screws on the market that have even been given a CE –marking. I also wrote about these in another blog, “Does the CE marking mislead?”
Inspection and maintenance of an old roof
In practice, the biggest problem with old roofs is not rusting through the sheet metal, but raised nails, and sometimes screws, and the local leaks that result from them. If there are only a few leaks and the roof is otherwise in good condition, they should be patched and the roofing fastened with a new roofing screw from the bottom of the profile, at a point where the batten is still hard. The batten has probably softened so much at the raised fastener that it is not worth putting a new screw in the same place. If there are many leaks, the entire roof should be replaced.
If the roof coating is PVC Plastisol, repainting it for maintenance is often pointless. The coating can be identified by strong fading on the southern slope. PVC Plastisol also often changes colour, and the paint starts to peel near the roof ridge. If repainting for maintenance must be done for some reason, the old paint must be completely removed before repainting. After that, the painting is done in the same way as painting galvanised sheet metal.
Scratches found on the roof, whether rusty or not, must be cleaned with a wire brush or lightly sanded and carefully repainted for maintenance, including a primer.
Repairing a rusty roof
Maintenance painting should be done well in advance of rusting and paint peeling. Then the work is easy and quick. Sheet metal suppliers have good instructions for this.
If the roof has started to rust more extensively, consider carefully whether it is worth undertaking maintenance painting. If the painting is done as a voluntary project for fun, then why not. When done as purchased work, maintenance painting of the entire roof does not really pay off. Maintenance painting can buy a little time, but in any case the roof will have to be replaced fairly soon. Once rusting has begun more extensively, nothing will stop it by any normal method that could be carried out reliably on the roof.
Finally, I would like to remind you to take care of safety. Use proper safety equipment when moving on the roof so that you do not injure yourself. And if you doubt your skills, use a professional. For both assessing the roof’s condition and for maintenance.