The short answer is yes and the long answer is:
If a roof has been painted before, irrespective of whether it’s tin or tile, we certainly can re-paint the roof, but it’s a matter of knowing that the paint applied is only as good as the paint that’s left after it’s cleaned. When we prepare via pressure cleaning a roof for re-sealing and painting we tend to like using at least 4000psi or more of pressure and 15-21L per minute flow rate, especially well with a previously painted roof – in order to hit the mould and dirt as hard as is practical. The common-sense theory is that if there’s paint or sealant left on the tile or tin after it’s been cleaned at high pressure and sometimes at high heat (if hot water pressure cleaning is required), then it’s good enough to re-paint. Only when there’s constantly flaking paint does the home owner run into more expense – where sometimes it’s just easier and better to replace part or all of the roof.
There’s several different sealers on the market that can ensure a great seal on the tile or tin. Tin roofs require a sealer that dust’s on and dries really really well, allowing the coloured paint the best chance of adhesion. Like all painting with spray devices, you’re always better off applying less paint than more, but increasing the number of coats applied. Tiled roofs are quite different and require a building-up process – whereby a thicker sealant can be applied more liberally with the security of usually having quite a porous and ideal surface for applying it.
Roof painting is about adherence, as it is about quality and durability of the paint being used. At Full Circle we endeavour to use the best quality materials available, with an accent on finding roof paints that are as hard as possible. The hardness of paint is a very big determining factor in whether dust (which turns into mould) and or other foliage will slide off the roof and away from the surface. Also, a harder paint just tends to do better with UV and doesn’t tend to turn chalky as fast either. More will be shared in a following blog about the quality roof paints sourced.