Multiwall Polycarbonate Fitting Instructions

When coming to estimate costs for your roofing project, in the initial stages to get a rough estimate, it is sufficient to have approximate sizes. However, when the timber structure is in place, be that for your conservatory, your carport or a lean-to, it is necessary to be particularly accurate with measurements. For that reason, the old adage of measure twice and cut once is very important.

We at Access Plastics will cut to your sizes (Free of Charge) and guarantee 100% accuracy on the length and on the width. Furthermore, we will actually blow out the sheets, removing all the plastic swarf and plastic sawdust from the sheets. We will also tape the sheets with solid tape at the wall end and vented tape at the guttering end, so that from your point of view all that needs to be done is to place the sheets on the roof and use the fixtures and fittings to fix it down into position.

It is important to get your dimensions correct from the outset. This will save a lot of time when it comes to installing the sheet. Keep your measurement in millimetres and be as accurate as possible. Allow a 12mm to 15mm gap between the sheets on a jointing rafter.

Once you have your sheet, which has been cut to size and has been solid taped at the wall end and has been vent taped at the end running into the gutter, it is ready to be installed. You can allow a 50mm to 60mm over run at the gutter end. When your order is delivered, it is recommended to layout all items and familiarise yourself before commencing the job. While we will supply the sheet with both solid tape and vented tape applied to the panels, you may also require some additional tape, which we will supply, if there is a need to cut the sheets in situ.

Having cut the sheet and offered the sheet up, a U profile is applied to the guttering end or the vented end of the sheet. The correct fashion is with the smooth end on the top and with the hole ends on the bottom to allow for any condensation or water to clear the profile.

Next you have the capping bars, available in 40mm or 60mm width. You have the black rubber gasket, which will sit on the rafter. You have the aluminium capping bar, which is bead gasketed both sides and is also pre-drilled and comes complete with 60mm long wood screws and the end cap to block the end of the bar which is running into the guttering and similarly at the top end.

With the F profile, the 2 short legs will fit over the sheet, the long leg will be drilled and screwed into the gable end rafter.

For the intermediary rafters, you have the fixing button, complete with the foam gasket and 60mm wood screw, along with the cap which goes over the top of the screw head, when it has been screwed home.

And finally the complete wall finishing profile, which will be used at the top of the sheet and fixed to the house wall and then drilled through the sheet, to the timber wall plate. Remember to always use neutral curing silicone. To complete your project, go to, where you will find further details in relation to the fitting instructions, a list of accessories and fittings required to fix your roof in position, along with all the pricing and various sizing and profiles available. Alternatively, please contact us on 01 8010022 or by email at We are here to help.