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Proper Installation of polycarbonate pergola roofing sheets.

Updated: May 3, 2021

Polycarbonate Sheets Installation Guidelines

The simplest method to install the polycarbonate sheets is to use the specifically designed Aluminum or Polycarbonate profiles to join the sheets. When installing always check the frame structure: purlins or rafters (or both)? This is important because you must determine the proper width of the sheets. To install 2 or more polycarbonate sheets on a roof you will need:

In most cases this is all you need to install polycarbonate sheets on a roof:

Polycarbonate Sheets before installing them on the frame you must follow a few steps of preparation:

  • Check for the UV protected side. This side must be installed on the top side of the roof facing skyward. Ours has UV coating on both sides, 50/50.

  • Close the Top edge of the width side of the sheets with Solid Aluminum Tape to prevent water and dust from getting inside the ribs

  • Close the Bottom edge of the width side of the sheets with Vented Aluminum Tape. This ensures condensation drainage, and blocks out dust and insects.

The H-aluminum profile is composed of a base and cape. The base must be screwed to the frame as this will allow reinforcement of polycarbonate roofing when the cap is then applied. The one-piece polycarbonate H-profile must not be screwed to the frame. This one is recommended for polycarbonate sheets of 16mm twin wall and is easier to use when your roof has “purlin” support or a combination of purlins and rafters. Your sheets will be secured by the screws and washers being applied directly through the polycarbonate sheets. (see manufacturers specifications for installation before every job) The U profile lets you close the top and bottom edge of the width side of the polycarbonate sheets. Choosing polycarbonate or aluminum material is just a matter of personal taste but it must be applied only after the solid aluminum and vented tape have been applied. Screws allow you to fasten the polycarbonate sheets to the frame. They must be used with the proper washer/neoprene gasket that must be applied between the screw head and the polycarbonate sheet. The gasket with its neoprene layer at the bottom and galvanized steel at the top distribute the stress evenly on the surface and seal the hole from water infiltration. When pre-drilling the hole for the screws, always consider the thermal expansion of the material by drilling a hole 1/8” wider than the screw thickness. The gasket will prevent any water leaks.

When cutting the polycarbonate sheets, use a circular saw with plywood blade (60, 80+ teeth) or jig saw with fine tooth blade. Always cut the sheet before taking off the protective PE film otherwise the static charge will attract fine chips to the flutes. For thinner sheets below 6mm in thickness you can use a utility knife. In conclusion, when installing a roof, you have a variety of material solutions. The adoption of plastic materials is increasing year after year due to their versatile and ease of installation. Here is a brief comparison of advantages and disadvantages:



  • Longevity

  • Light clarity


  • Fragile

  • Poor thermal efficiency

  • Not easy to install



  • Easy To install

  • Thermal Efficiency

  • Natural light inside through the spaces

  • Lightweight

  • 100% Recyclable

  • Low Cost

  • Easily formed into radiuses

  • Easily cut to size


  • Limited life (15-20 years) and subject to UV damage

  • Easy to scratch

Polycarbonate addresses all the disadvantages of Glass and brings two new advantages: thermal insulation, and no required expertise for the installation. For this reason, polycarbonate is very popular in Europe, Asia, and South America where more architects opt for Polycarbonate sheets on projects big and small. Polycarbonate Sheets can be extruded in different thicknesses for improved structural integrity and greater thermal efficiency.

Contact us @ 561-299-8276 and let us help you with your next DIY Pergola Roof.

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Thanks for this great guide on installing polycarbonate roofing sheets! The instructions seem very thorough and easy to follow. I was particularly interested in the point about drilling the holes wider than the screw thickness - that's a detail I probably wouldn't have thought of otherwise.

One question I did have is whether there are any special considerations for installing polycarbonate roofing in colder climates? Does the material become more brittle in freezing temperatures? Any additional tips you could share for cold-weather installation would be greatly appreciated!


The way you have explained is really great, anyone who is new to the roof repair business can use such information to install new roofs.

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