Over the last several years we have published Fact sheets 015 and 044. These two fact sheets dealt specifically with timber weatherboards and Colorsteel roofing iron. While these two fact sheets remain relevant to these surfaces, delamination can be seen on a range of different substrates.
This delamination is often caused by the failure of previous paint coating systems. These paint coatings become old, brittle and loose adhesion from the substrate they have been applied to.
On older roofing iron that has been painted on many occasions over the years delamination can often be seen at the water blasting and cleaning stage of the work. In many cases it will be extremely difficult to prepare the damaged paint coatings as the edges of the old damaged coatings can lift and curl when overcoated with a new paint coating system.
It is possible that even with thorough and properly carried out preparation, blistering of the roof coatings can appear after painting is completed. In many cases this blistering is caused by the previous coats of paint applied to surface, sometimes many years ago, that are now losing adhesion under the new paint coating system. This is especially likely on older roofing iron where oil based paint products may have been used.
Blistering of the roof coatings is now becoming common place and is one of the reasons why the Master Painters Association 5 Year Guarantee excludes roof coatings.
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