Toni Stella, National Training Manager of the SAPMA, 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 he 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 paint work starts unless the roof is more than a year old and has weathered sufficiently for all the oil from the fabrication to have worn away. Unpainted galvanised iron 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. You should spray sections of about a meter in width and work your way down the sheet, spraying in the direction of the flutes in corrugated iron. Once you have worked your way, move back to the top of the roof and repeat the application on the next sheet. You must keep a wet edge at all times – that is why it is important to start painting the top of the roof before the paint starts to dry. If you work from the bottom to the top, the top part could already be tacky by the time you get back up there.
“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,” Stella advises.
“For painting tiled roofs, a primer or roof sealer should be liberally applied followed by two coats of suitable paint. Airless spraying is also 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 overlaps.
“You could also paint a tiled roof with a brush but this really is a long and grueling task. Rather hire an airless spray gun: the rental cost will be offset by the time saved,” Stella concludes.