Will Polycarbonate Patio and Pergola Roofing Be Too Hot in Summer?

One of the most common questions when selecting a pergola roofing system is: Will polycarbonate roofing make it too hot in summer? This concern arises because polycarbonate roofing is clear, allowing plenty of light in.

The challenge many face is how to balance light and heat in their pergola or outdoor living area.

Before diving into the details, it's important to understand where heat comes from. Sunlight contains three major components: UV rays, infrared (IR) rays, and visible light. Infrared rays are the primary source of heat from the sun, so to reduce heat, we need to block IR. However, some materials also block visible light when blocking IR rays, which can affect brightness.

In this article, we test three ExcelitePlas pergola roofing materials and compare their ability to manage visible light, infrared rays, and UV radiation. For a deeper dive into how IR-blocking technology works, see our article on how IR-blocking treatment works on polycarbonate roof sheets.

1. Clear Polycarbonate Pergola Roofing

Clear polycarbonate sheets allow the most visible light and IR rays. Since all ExcelitePlas polycarbonate sheets are UV-rated, they block 99–100% of UV rays regardless of tint.

We tested clear solid polycarbonate sheets, the polycarbonate solid locking system, and clear twin-wall polycarbonate sheets. Despite their different designs, they offer similar heat management properties.

Clear Solid Polycarbonate Sheet

• Visible Light Transmission (VLT): 89%
• Infrared Ray Resistance (IRR): 8.6% heat blocking
• UV Ray Resistance (UVR): 100%

Clear Twin-Wall Polycarbonate Sheet

• Visible Light Transmission (VLT): 79% (10% less than clear solid sheet)
• Infrared Ray Resistance (IRR): 24% (16% more than clear solid sheet)
• UV Ray Resistance (UVR): 99%

2. Tinted Grey Polycarbonate Roofing

Tinted grey pergola roof sheets offer the look of glass, allowing you to enjoy views of the sky while providing meaningful shade. They block 50% of the sun's infrared rays (heat) and allow around 20% of natural light through — a great balance for outdoor living spaces like pergolas, patios, and verandas.

We tested a 4mm Grey Tint Polycarbonate Solid Sheet and a Grey Tint Twin-Wall Polycarbonate Sheet.

Tinted Grey Polycarbonate Sheet Test Results

• Visible Light Transmission (VLT): 20%
• Infrared Ray Resistance (IRR): 52% heat blocking
• UV Ray Resistance (UVR): 100%

3. Gallina Translucent Multiwall Roof System (Arcoplus 684 / 920)

If you want maximum heat reduction while still allowing plenty of light, the Gallina Arcoplus 684 multiwall roof system is the ideal choice. It uses a "Clear but Cool" transparent IR protection layer, providing exceptional heat reduction — lowering temperatures by up to 15°C.

Gallina 8mm Multiwall Polycarbonate Sheet Test Results

• Visible Light Transmission (VLT): 20%
• Infrared Ray Resistance (IRR): 83% heat blocking
• UV Ray Resistance (UVR): 100%

Same light transmission as tinted grey polycarbonate, but the Gallina Arcoplus 684 blocks 30% more heat than tinted grey sheet.

Which Polycarbonate Roofing is Right for You?

Choosing the right pergola roofing material allows you to stay cool and comfortable under a polycarbonate roof. Here's a quick summary:

• Clear polycarbonate: Maximum light (89% VLT), minimal heat blocking (8.6% IRR) — best for cool climates or shaded aspects.
• Tinted grey polycarbonate: Balanced option — 20% VLT, 52% IRR — ideal for most Australian pergolas and patios.
• Gallina Arcoplus multiwall: Best heat performance — 20% VLT, 83% IRR, lowers temperature by up to 15°C — ideal for north-facing pergolas in Melbourne, Sydney, and Queensland.

All ExcelitePlas polycarbonate roofing options are 100% UV blocking and fully weatherproof. For installation guidance, see our polycarbonate pergola roofing installation guide.

Contact our team for advice on the best roofing solution for your climate and pergola design.