How to Install Polycarbonate Roofing Sheets

Before starting your installation, it's worth gathering everything you'll need. Having the correct tools and materials close by will make the job quicker, safer and much less stressful.

For a typical polycarbonate roof installation, we recommend having the following:

Essential Tools

• Tape measure

• Pencil or marker

• Spirit level

• Cordless drill and suitable drill bits

• Fine-tooth saw or circular saw with a suitable blade (if sheets require trimming)

• Step ladder or suitable access equipment

Roofing Materials

• Polycarbonate roofing sheets

• Glazing bars

• End closures

• Breather tape

• Foil tape

• Fixing buttons (where required)

• Suitable fixings for your roof structure

Before you begin fitting the roof, lay all of the components out and check that nothing is missing. It's much easier to replace or reorder an item before installation starts than halfway through the project.

Before fitting any roofing sheets, it's important to make sure the supporting structure is ready. A well-built frame is the foundation of a successful installation, and taking a few minutes to check everything now can prevent problems later.

Start by checking that all rafters are securely fixed and evenly spaced. They should be straight, level and free from any movement. If a rafter is twisted or out of alignment, it's much easier to correct it before the roofing sheets are installed.

Next, check that the roof has the correct fall. Polycarbonate roofs should always be installed with a suitable slope to allow rainwater to drain away efficiently. Standing water can reduce the performance of the roof and increase the amount of maintenance required over time.

Before fitting any components, remove any dirt, sawdust or debris from the framework. A clean working area makes installation easier and helps ensure the glazing bars and roofing sheets sit correctly.

Finally, compare your completed roof frame with your original measurements. This is your last opportunity to identify and correct any issues before installation begins.

Once your roof structure has been checked, the next step is to install the glazing bars. These form the framework that supports the polycarbonate sheets and keeps them securely in place.

Begin by positioning each glazing bar over the rafters, ensuring they're straight and evenly spaced. Taking your time here is important, as any misalignment will become much more noticeable once the roofing sheets have been fitted.

Secure the glazing bar bases to the rafters using the recommended fixings, making sure they are firmly fixed without over-tightening. Work along the roof one glazing bar at a time, checking with a spirit level as you go to ensure everything remains straight.

Before moving on, double-check the spacing between each glazing bar. This should match your planned sheet layout so that every polycarbonate sheet is fully supported along both edges.

Once all of the glazing bar bases have been installed, you're ready to fit the sealing tapes and prepare the polycarbonate sheets.

Before installing the sheets, it's important to prepare them correctly. Taking a little extra time now will help protect the sheets from moisture, dirt and insects, while ensuring they perform as intended for many years.

Check the UV Protected Side

Polycarbonate roofing sheets have a UV protective layer on one side only. This side must always face upwards towards the sun. Most sheets are supplied with a protective film that's clearly marked to indicate which side should face the sky.

Don't remove the protective film until you're ready to complete the installation. It helps protect the sheet from scratches while you're handling and fitting it.

Apply the Sealing Tapes

The top end of each sheet should be sealed using foil tape. This prevents dirt, dust and insects from entering the internal flutes.

The bottom end should be sealed using breather tape before fitting the end closure. Breather tape allows any condensation that forms inside the sheet to drain away while helping to prevent insects and debris from entering.

Using the correct tape in the correct position is one of the most important parts of the installation process.

Fit the End Closures

Once the tapes have been applied, fit the end closures to the top and bottom of each sheet. These provide a neat finish, help protect the tapes and improve the overall performance of the roofing system.

Before lifting the sheets onto the roof, check one final time that the UV protected side is facing upwards and that the correct tape has been fitted to each end.

With the roof structure prepared and the sheets correctly taped and orientated, you're ready to install the polycarbonate sheets.

Always lift the sheets carefully into position and avoid dragging them across the roof structure or other sheets, as this can damage the protective film or scratch the surface.

Place the first sheet onto the roof, ensuring it sits squarely between the glazing bars. The sheet should rest naturally within the glazing system without being forced into position.

As you continue across the roof, fit each additional sheet in the same way, checking that the spacing remains consistent and that every sheet is fully supported along both edges.

Polycarbonate expands and contracts as temperatures change, so it's important to allow for thermal movement during installation. Never force the sheets tightly into the glazing bars or fix them so they cannot move naturally. Allowing the sheets to expand and contract freely will help prevent unnecessary stress and ensure the roof performs correctly throughout the year.

Before fitting the glazing bar caps, stand back and check that all of the sheets are sitting straight and evenly aligned. Making small adjustments now is much easier than after the roof has been fully secured.

With all of the polycarbonate sheets correctly positioned, the final step is to secure the roofing system and carry out a thorough inspection before removing the protective film.

Fit the glazing bar caps according to the manufacturer's instructions, working along the roof one section at a time. As each cap is fitted, check that the polycarbonate sheets remain correctly aligned and haven't moved out of position.

Once the glazing bars have been secured, fit any remaining end caps, flashings or finishing trims required for your roofing system. These components help protect the roof from the weather while giving the installation a neat, professional appearance.

Before removing the protective film, walk around the roof and carry out a final visual inspection.

Check that:

• Every sheet is sitting correctly within the glazing bars.

• The UV protected side is facing upwards.

• Foil tape has been fitted to the top of every sheet.

• Breather tape has been fitted to the bottom of every sheet.

• End closures are fully fitted.

• All fixings are secure but not over-tightened.

Once you're satisfied that everything has been installed correctly, carefully remove the protective film from both sides of the sheets. Leaving the film on for long periods after installation can make it much more difficult to remove later.

Your new polycarbonate roof is now ready to enjoy.