How to apply Lap Mastic to Insulated Panels

Transcript

When fitting insulated panels, it’s important to use the correct mastic to avoid water and cold air penetration. Both can reduce effectiveness and invalidate the products guarantee. For the best seal, always use 5mm wide by 6mm thick high-grade, butyl lap mastic. This leaves a slight gap between the sheet overlaps, which prevents the deterioration of the coating.

Ideally, you would only use one sheet from ridge to eaves to avoid end laps. But, on some roofing projects, you might need to use more than one. Maybe for ease of handling, span capabilities or when fitting a rooflight. If this is the case, before fixing, apply three continuous beads of high-grade, butyl lap mastic across the width of the sheet. You’ll need two runs either side of where the main fixings will go, with the third being 10mm from the nominal edge.

Take care not to stretch the mastic out, and ensure it follows the contours of the profile. Once the top panel is fixed into position, apply the side lap seal continuously from ridge to eaves along the crown of the sheet. It’s now ready for the next sheet to be laid.

Be sure to watch out video on how to fix insulated panels.