Polycarbonate materials expand and contract with temperature changes. Therefore, thermal movement must be considered before and during polycarbonate roof sheet installation.

Expansion-friendly installation practices

Polycarbonate is highly durable and impact resistant. However, if you wish to build your own pergola, care must be taken during installation to ensure the long-term performance and appearance. Here’s how to accommodate thermal expansion in polycarbonate sheets:

Plan a space for movement: Keep enough room to compensate for thermal expansion, leaving a small gap where they meet another object (your lean-to pergola wall, for example). Sheets expand most along their length, so pay attention to this direction. Multiwall polycarbonate sheets will move along the ribs’ direction, and profiled polycarbonate sheets expand along the corrugation lines.

Pre-drilled oversized holes: This cannot be emphasised enough. Pre-drill oversized holes around the fixing’s location. Expanding the holes will prevent stress and ensure long-lasting roof performance.

Do not overtighten: Secure all your fixings properly for safe and durable performance. However, remember that over-tightening can cause distortion and excessive stress, ultimately causing material failure.

Use suitable fixings: Flexible EPDM gaskets allow just enough free movement for the sheets as they contract and expand. This ensures a secure seal against leaks and reduces stress and micro crack formation around the fixing. Combine these gaskets with self-tapping screws for timber purlins, or with self-drilling screws for metal purlins. Make sure the screws are corrosion-resistant for optimal long-term service.

Use polycarbonate compatible sealants: Silicones can act as effective sealants, but some silicones can also affect polycarbonate sheets. If you can’t avoid it, use a neutral cure or non-acidic silicone approved for polycarbonate. Do not use bitumen-impregnated foam infills. These will damage the polycarbonate sheets.

Installing polycarbonate roofing

Managing thermal expansion in polycarbonate panel systems

SUNPAL and SUNGLAZE are standing seam panel polycarbonate roofing systems with free expansion joints. By using these systems, you don’t need to worry about pre-drilling or other thermal expansion measures. The system panels are clicked in place and can expand and contract freely while secured to the roof system. These lightweight and leak-proof solutions can withstand high loads and adapt to thermal expansion and contraction.

Both systems provide design flexibility for various architectural requirements and ensure durability for long-term use.

SUNGLAZE is a widely used glazing solution for home and outdoor roofing, just as it is used for complex engineering. It consists of flat, solid polycarbonate roofing panels with edges that fit into a standing seam glazing system.

SUNPAL is a multi-wall polycarbonate panel system. In addition to natural light, it provides thermal insulation and structural strength.

Polycarbonate roofing

Climate considerations and thermal properties

Polycarbonate sheeting’s type and thickness are crucial considerations before installation. This is a matter of thermal insulation and weather resistance, and not thermal movement behaviour. It is advisable to use 3mm polycarbonate sheets in areas with more extreme climates, as they can withstand hail, ice, snow and wind better than thin-walled panels.

If you are bracing yourself for a cold winter, remember the thumb rule: more layers mean better insulation. Depending on your intended purpose, you can use twin-wall or multiwall sheets.

Below you will find examples of ideal thicknesses for common projects:

6 to 10 mm multiwall SUNLITE DIY: Covering for gazebos, DIY greenhouses, cold frames, DIY garden sheds.
10 to 16 mm multiwall SUNLITE DIY: Sunrooms, conservatories, pool enclosures, permanent patio canopy, carports.
0.8mm corrugated SUNTUF DIY: Lightweight garden roof cover, or patio rain cover.
Hail-resistant SUNTUF Beehive & EZ Glaze: Glass roof replacement, solid roof pergola and hail-resistant canopies.
Panel systems: Skylights, designed canopies, and clear polycarbonate roofing.

Polycarbonate roofing

Impact on long-term performance and durability

Proper management of thermal expansion in polycarbonate roofing is crucial to ensuring its long-term performance and durability. If not controlled, thermal expansion can lead to bowing, warping, and cracking of the material, substantially reducing its lifespan.

Failure to account for thermal expansion can lead to structural issues, leaks, and premature sheet aging. Make sure you have the right type of system and take adequate precautions when installing polycarbonate roofing.

Polycarbonate roofing

Ensuring successful polycarbonate roofing installation with thermal expansion in mind

By choosing the right type of system, and installing it properly, you can ensure your roofing lasts. With proper care and maintenance of your polycarbonate roofing system, you should enjoy its benefits for a long time. Most polycarbonate sheets have a 25-year life expectancy, so ensuring your roofing is installed correctly will pay off.

Architecture & Design Team

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Palram Australia

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