Polycarbonate Roofing Sheets

What Are Polycarbonate Roofing Sheets?

Polycarbonate Roofing Sheets are durable, lightweight panels made from a strong type of thermoplastic polymer called polycarbonate. They are specifically designed and widely used in the UK for roofing and overhead glazing applications where light transmission, high impact resistance, and ease of handling are important. 

Applications

Our Clear Twinwall and Clear Triplewall sheets are highly versatile and ideal for numerous applications across the UK where durability, light weight, and maximum natural light transmission are key requirements:

• Greenhouse Glazing: The perfect choice for greenhouses, providing excellent light for plant growth, improved safety compared to glass, and beneficial thermal insulation (Clear Twinwall is commonly used).
• Carports & Canopies: Create bright, UV-protected shelters for vehicles or entranceways. Clear Twinwall (e.g., 10mm) or Clear Triplewall (e.g., 16mm for better insulation/rigidity) are popular choices.
• Pergolas & Patio Covers: Extend the usability of outdoor seating areas by adding a bright, weather-protective roof covering that doesn't significantly darken the space.
• Lean-To Roofs & Porch Covers: A lightweight, easy-to-install solution for home extensions, porches, or covered utility areas where maximising daylight is desired. Triplewall offers enhanced thermal performance for these spaces.
• Covered Walkways & Cycle Shelters: Provide durable, naturally lit, weather-protected routes or storage areas for schools, offices, or public spaces.
• Swimming Pool Enclosures: Offer a safe (shatterproof) glazing option with good light transmission and the insulating properties needed to help manage heat loss and humidity (Triplewall often preferred).
• Insulated Rooflights: Suitable for incorporating into solid roof structures (sheds, workshops, garages, industrial units) to introduce natural daylight without significant heat loss compared to single-skin options.
• DIY Projects & Hobby Greenhouses: Excellent for various home projects, cold frames, cloches, animal shelters, or custom-built garden structures needing a clear, strong covering.

Important Note on Conservatories: While multiwall polycarbonate is frequently used for conservatory roofs, selecting Clear sheets requires careful consideration. The very high light transmission also means high solar heat gain, which can make conservatories uncomfortably hot in summer without excellent ventilation and/or shading. For occupied conservatories, tinted or specialist solar control polycarbonate sheets are often recommended to manage heat and glare more effectively.

Benefits

• Incredible Strength & Impact Resistance: Virtually unbreakable, polycarbonate is approximately 250 times stronger than glass and significantly tougher than acrylic, offering excellent protection against impacts, hail, and vandalism.
• Lightweight: Significantly lighter than glass, making it easier, safer, and cheaper to transport, handle, and install. It often requires less substantial supporting structures.
• Excellent Light Transmission: Clear polycarbonate sheets allow high levels of natural light transmission, comparable to glass, creating bright, inviting spaces. 
• UV Protection: Most sheets feature a co-extruded UV protective layer on one or both sides. This blocks harmful ultraviolet radiation, protecting people, plants, and furnishings below, while also preventing the sheet itself from yellowing or degrading prematurely.
• Thermal Insulation: Multiwall polycarbonate structures provide thermal insulation (measured by U-value), helping to retain heat in winter and reduce excessive heat gain in summer compared to solid sheets or glass. Thicker sheets offer better insulation.
• Weather Resistance: Designed to withstand a wide range of UK weather conditions, from sun and rain to wind and snow loads (when correctly installed to manufacturer specifications).
• Easy to Work With: Polycarbonate can be easily cut to size on-site using appropriate tools and is relatively simple to drill for fixings.
• Fire Performance: Polycarbonate has improved fire resistance properties compared to some other plastics. Specific fire ratings (e.g., to UK Building Regulations Part B standards) vary by product - always check manufacturer certifications. It typically self-extinguishes when the flame source is removed.

Clear Twinwall Polycarbonate

• Structure: 2-layer sheet with a single row of insulating air channels (flutes).
• Key Features: Maximum light transmission (Clear), good thermal insulation, high impact resistance, lightweight, UV protected surface.
• Best For: Greenhouses, cold frames, simple canopies/shelters where maximum light is the priority.

Clear Triplewall Polycarbonate

• Structure: 3-layer sheet with two rows of insulating air channels (flutes).
• Key Features: Superior thermal insulation and rigidity compared to Twinwall. Also delivers maximum light (Clear), high impact resistance, lightweight, UV protected surface.
• Best For: Quality carports, pergolas, lean-tos, and porch covers requiring better insulation, reduced condensation risk, or increased strength/spanning capability.

Installation Overview & Key Principles

While specific instructions vary by system, general principles apply:

• Support Structure: Sheets require adequate support from rafters or purlins. Spacing depends on sheet thickness (Twinwall/Triplewall) and anticipated wind/snow loads - refer to manufacturer guidelines.
• Expansion Allowance: Polycarbonate expands/contracts with temperature. Leave clearance where sheets meet walls/trims and use oversized fixing holes within glazing bar systems.
• UV Protected Side: CRITICAL: Always install with the UV-protected side facing outwards (upwards). This side is clearly marked on the removable protective film. Incorrect installation voids warranties and leads to premature degradation.
• Multiwall Sheet Sealing: Open ends of the flutes MUST be correctly sealed: 
  • Use solid aluminium sealing tape on the top edge (highest point).
  • Use vented anti-dust breather tape on the bottom edge (lowest point/gutter end) to allow condensation drainage.
• Fixings & Glazing Bars: Our Twinwall and Triplewall sheets must be installed using compatible glazing bar systems (e.g., rafter-supported PVC or Aluminium capped bars). These systems join sheets, secure them to the structure, incorporate gaskets, and allow for thermal movement. Do not simply screw through the sheet.
• Edge Trims: Use U-profile end closures over the sealing tapes to protect the flutes and provide a neat finish. Use F-profile trims for neat edges against walls.
• Cutting: Use a fine-toothed jigsaw or circular saw with a suitable blade. Support the sheet well during cutting.

Essential Accessories for Twinwall & Triplewall Installation

• Glazing Bars: Essential for joining sheets and fixing to rafters. Choose compatible systems (PVC Capped or Aluminium Capped Rafter Supported Bars are common). 
• Sealing Tapes:
  • Aluminium Foil Tape: For the upper/top end of flutes.
  • Anti-Dust Breather Tape: For the lower/bottom/gutter end of flutes.
• Edge Trims:
  • U-Profile End Closures: To cap off the sealed flute ends neatly. Ensure correct size for sheet thickness.
  • F-Profile Edge Trims: For finishing sheet edges neatly against abutting walls.
• Sheet End Closures: Sometimes used as a drip edge at the gutter end, especially on conservatory-style roofs, fitting beneath the U-profile/sheet.
• Low Modulus Neutral Cure Silicone Sealant: For weather-sealing joints between edge trims/sheets and abutting walls or around flashings. Must be polycarbonate compatible.

How to Choose Between Our Clear Twinwall & Triplewall Sheets

Consider these factors when selecting from our range:

• Application & Insulation Needs:
  • Greenhouses/Cold Frames: Clear Twinwall (e.g., 4mm, 6mm, 10mm) is often sufficient, prioritising maximum light.
  • Canopies, Carports, Pergolas, Lean-tos: Clear Twinwall (e.g., 10mm) offers a good balance. Clear Triplewall (e.g., 16mm) provides better thermal insulation (less heat loss, reduced condensation risk underneath) and potentially greater rigidity/spanning capability - often preferred for higher-quality structures or where minimising condensation is important.
• Light & Heat: Both our Clear options provide maximum light transmission. Neither significantly reduces solar heat gain. If reducing heat is critical, external shading might be needed.
• Budget: Generally, Twinwall may be more economical for a given area than Triplewall, especially when comparing thinner Twinwall to thicker Triplewall. Balance cost against the desired level of insulation and rigidity.
• Structure & Span: Thicker sheets (often Triplewall options like 16mm) generally offer greater rigidity and may allow for wider rafter spacing compared to thinner Twinwall sheets. Always consult manufacturer load and span data for the specific sheet thickness.
• Aesthetics: Both options provide a clean, bright appearance due to being Clear. The main visual difference is the internal structure (single vs. double row of flutes).