Expansion and Contraction

With changes in temperature sheets can expand or contract approx 3mm per metre in both directions so allowance must be made for this movement. Ensure the glazing bars you use allow for this and that the bar caps can move with the glazing sheet. Each sheet should be screwed down at one end. Do remember to oversize the fixing hole by 3mm. The sheets are normally screwed down at the back wall plate or ridge so that the screws are covered by the flashing. This prevents the sheet creeping down the glazing bar as it contracts and expands.

Sealing the Sheet Flutes

The air inside the sheet flutes must be allowed to expand i.e. the sheet must breathe. The top end of the sheet is sealed with self adhesive aluminium tape whilst the bottom (usually the gutter end) is taped with with breather anti-dust tape. Taping is essential to prevent the ingress of dirt and insects. A sheet closure extrusion is usually fixed to the bottom of the sheet to protect the breather tape and provide a neat appearance.

Roof Lamterns

Another great addition to your roof are Upvc roof lanterns. We provide these as a kit ready to install on site and they are available from our website.