Topcoating the roof
Taking care and paying attention to detail at this stage of the roor coating will produce a roof of superb appearance.
- Before topcoating, lightly sand the corners and trim bandages with a 40 grit sand paper, then cut away any excess matting beyond the trim, with a sharp knife. Seal any areas against walls using a clear silicone sealant. Finally, fit any C100 simulated lead flashing before topcoating and seal with a clear silicone sealant
- The topcoat is a resin and requires the addition of a catalyst for it to cure (if you have purchased a kit the exact amount required will already have been worked out for you)
- Always try to apply the topcoat after the laminate is semi-cured (no stickiness). If this is not possible, topcoating should be applied within 24 hours to ensure a good bond with the laminate. After 24 hours, wash down the laminate with acetone to gain a good cross polymerisation of the topcoat to laminate
- Remove the lid of the top-coat and stir well, ensuring the strene and wax at the bottom of the tin is fully mixed
- Pour out enough topcoat into a mixing bucket to cover the perimeter of the roof (including edge trims)
- Use a 2½ inch roller to coat the trims, rolling along the face of the trims
- To protect the fascia from topcoat, hold a piece of flashing trim against it as you topcoat the radius on the underside of the trim
- Calculate how much topcoat will be needed to cover the main body of the roof (applied at a rate of 0.5kg/m2), then add the required amount of catalyst and stir well
- Using a 7 inch polyester roller cover the remaining laminate with just enough topcoat for the fibre pattern to be visible. (If applied too thickly, the topcoat will crack).
- If a coloured topcoat is wanted, rather than the standard grey, a colour pigment can be added at the rate of 2kg of pigment to every 20kg tin of topcoat
- It is essential to mix any pigment thoroughly into the topcoat, to avoid patchiness and uneven colour.