Roof coating
Application
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Adhesion Test
[edit | edit source]An adhesion test must be done to ensure compatibility with the existing substrate. To perform adhesion tests in the field, the fabric pull test[1] is recommended. The initial adhesion measured in this test does not mean that long term adhesion is assured but it does provide a strong indication of adhesion performance.
- Clean test area thoroughly and let dry.
- Do not perform an adhesion test on a rusted surface without rust treatment or primer. Silicone coatings should be mechanically removed from substrate.
- Apply 15 mils of roof coating on the prepared or primed surface (min 6″x6″).
- Embed a 2″x6″ swatch of polyester fabric into the roof coating. Allow 2″ of the fabric to hang free.
- Apply another 15 mils of roof coating on the fabric until it is completely concealed.
- Allow roof coating to dry and cure for at least 3 days. (10 days recommended to avoid false positives.)
- Test for coating adhesion by pulling the fabric at a 90° angle to the substrate surface.
- Some roof coating should remain on the substrate (see picture above). A clean pull indicates weak coating adhesion on the tested substrate.
Preparation
[edit | edit source]Inspect the roof for flaws, loose fasteners, cracks, gaps or tears. These need to be fixed before the roof is pressure washed. The roof surface must be thoroughly cleaned by pressure washing using a biodegradeable detergent. Allow the roof to dry thoroughly before applying any coating.
Priming
[edit | edit source]Primers improve the adhesion between the existing roof substrate and topcoat. On some roofs, priming may be optional but they are a small price to pay for peace of mind. If in doubt, always use a primer.
Coating Application
[edit | edit source]The roof coating is usually applied in 2 to 3 separate layers. To aid waterproofing, each layer should be applied at a 90° angle to the previous layer and polyester fabric can be used on seams and flashings. Always let the last coat dry before applying another one on top. The base coat may be tinted to facilitate drying and to ensure even coverage of the finish coat.