Painting a roof may appear a simple task but it is important to follow essential guidelines to do a perfect job, says Tara Benn, executive director of the SA Paint Manufacturing Association (SAPMA).
Tara says the first step in painting a corrugated/IBR iron roof – or any roof for that matter – should be to thoroughly clean the roof. This could be done with a broom and hose but for best results she advocates the use of a high-pressure water blaster which provides maximum penetration of spots that are hard to access.
“A new iron roof must be washed with a degreaser before painting starts. A galvanised iron cleaning type of solution for the removal of contaminants and possible oxidation layer is recommended. Such a cleaner would normally also help to key and etch the non-ferrous surface without damaging the zinc layer. Alternatively, a degreaser can be used in conjunction with large heavy-duty scour pads to provide the necessary key to promote long-term adhesion,” Tara advises.
“The galvanised iron roofs must first receive a suitable primer followed by two coats of paint. Colour is a personal choice but bear in mind that lighter colours will reflect the heat, providing a cooler interior.
“Airless spraying is the quickest way to paint any roof, but this process calls for a certain technique when it comes to iron roofs. You should spray sections of about a metre in width and work your way down the sheets, spraying in the direction of the flutes on corrugated iron roofs. Once you have worked your way down, move back to the top of the roof and repeat the application on the next sheet. You must always keep a wet edge: that is why it is important to start painting the top of the roof before the paint starts to dry.
“You can also use rollers shaped like corrugated iron but, although they work well, you will still have to make sure that the paint reaches all the corners and ridge caps. You could also use a simple brush to paint the entire roof, but it is a laborious task, and you have to start early in the morning to avoid painting in the heat of the day, particularly in summer when the paint will dry far too quickly. Another thing to remember is to paint in small sections – similar to spraying – but with a brush, rather do half-sheet widths at a time. Also make the overlap mark the hollow of the corrugated iron and not the top of the ridge,” Tara states.
“For painting tiled roofs, a primer or roof sealer should be liberally applied followed by two coats of suitable paint. Here, also, airless spraying is recommended with the following technique: paint about four tiles down from the top, and then paint across the roof until you get to the other end. From there, go back to where you started and repeat spraying about four tiles down again. Then continue across the roof to the other end. Each time you start a section, paint up to the bottom edge of the previous tile painted. This system will help avoid visible overlaps.
“You could also paint a tiled roof with a brush, but this really is a long and gruelling task. Rather hire an airless spray gun: the rental cost will be offset by the time saved,” Tara concludes.
“A new iron roof must be washed with a degreaser before painting starts.”