Polycarbonate roofing is a lightweight, semi to fully transparent plastic roofing that comes in three main forms: single-skin corrugated sheets, hollow twinwall and multiwall panels, and flat solid sheets. It carries daylight into a space while resisting impact far better than glass, which is why it dominates patio covers, carports, greenhouses, and skylights. This guide compares the panel types by thickness, light transmission, cost, and use, then walks through how the panels go on and the mistakes that cause leaks.
What is polycarbonate roofing?
Polycarbonate roofing is a thermoplastic sheet roofing that transmits daylight and shrugs off impact. Solid polycarbonate can be up to 200 times stronger than standard glass of the same thickness while weighing roughly half as much, per supplier data. It is sold as thin corrugated sheets, hollow twinwall or multiwall panels with internal ribs, and clear flat solid sheets. Most panels carry a factory UV coating on the weather side to slow yellowing.
The material is not the same as PVC or acrylic. Compared side by side with polycarbonate versus PVC roofing sheets, polycarbonate wins on impact strength and heat tolerance, while PVC costs less. Against acrylic it is less clear but far harder to crack.
Polycarbonate panel types compared: corrugated, twinwall, and solid
The three polycarbonate roofing forms trade clarity, insulation, and price. Corrugated is the cheapest single-skin option and passes the most light but adds no thermal barrier. Twinwall and multiwall panels trap air in hollow flutes for insulation, at the cost of some light and higher price. Solid sheets give the highest clarity and strength. The table below sets typical figures side by side; exact numbers vary by brand, tint, and market.
| Panel type | Typical thickness | Light transmission (clear) | Cost per sq ft (material) | Common uses |
|---|---|---|---|---|
| Corrugated (single-skin) | About 0.8 to 1.2 mm profile | High, single skin passes most light | Often about $2 to $3 | Carports, sheds, covered walkways, patio covers |
| Twinwall / multiwall (hollow) | Twinwall 4, 6, 10 mm; multiwall 16, 25, 35 mm | About 79% at 10 mm clear; roughly 50 to 82% by wall count and tint | Often about $3 to $6 | Greenhouses, skylights, insulated patio and pergola roofs |
| Solid (flat sheet) | 2 to 12 mm | Up to about 89% | Often about $4 to $6 and up | Canopies, glazing, security roofing, high-clarity roofs |
Corrugated polycarbonate
Corrugated polycarbonate is a thin single-skin sheet pressed into a wavy profile for stiffness and water runoff. It is the lowest-cost polycarbonate roofing and the easiest to cut and fit, which is why it covers most DIY carports, sheds, and walkway roofs. The single skin passes a high share of light but gives almost no insulation, so interiors heat up under sun. Profiles are made to match common metal patterns such as the Suntuf and Palruf lines sold at home centers.
For the wider family of wavy plastic panels, including PVC and fiberglass versions, see our guide to corrugated plastic roofing profiles.
Twinwall and multiwall polycarbonate
Twinwall and multiwall polycarbonate panels have two or more skins joined by internal ribs, creating hollow flutes that trap air for insulation. A 10 mm clear twinwall passes about 79% light with a U-value near 3.2 W/m2K, while thick multiwall panels can reach a U-value as low as 0.83 W/m2K, per supplier figures. Twinwall is sold in 4, 6, and 10 mm; multiwall in 16, 25, and 35 mm. These are the panels used on greenhouses and insulated patio roofs where heat retention matters.
Tint changes both light and heat. In 10 mm twinwall, clear passes roughly 79%, bronze about 35%, and opal about 30%, so opal and bronze cut glare and solar gain under a seating area. Opal also diffuses light evenly, which many growers prefer for greenhouse roof panels.
Solid polycarbonate
Solid polycarbonate is a flat single-layer sheet with the highest clarity and strength of the three forms. Clear solid sheet transmits up to about 89% light and can be up to 200 times stronger than glass of equal thickness, per manufacturer data. It is sold from 2 to 12 mm and used where appearance and impact resistance matter more than insulation, such as canopies, entrance roofs, and security glazing. It costs the most per square foot and, as a single skin, offers little thermal break on its own.
How much does polycarbonate roofing cost?
Polycarbonate roofing panels commonly run about $2 to $6 per square foot for material, with a standard sheet often priced around $50 to $80, per supplier and retailer listings. Corrugated single-skin sheets sit at the low end, twinwall and multiwall in the middle, and thick solid sheet at the top. Price climbs with thickness, UV coating, tint, and panel size. These are material figures only; glazing bars, fasteners, and labor add to an installed total.
Accessories matter more than buyers expect. Polycarbonate needs matched glazing bars or a compatible metal-roof closure system, foam eaves fillers, and fasteners with sealed cap washers, and those parts can add a meaningful share to a small roof. For a broader price comparison across transparent options, see our breakdown of clear roof panel options and of PVC roof panels.
What thickness of polycarbonate roofing do you need?
Thickness depends on the panel type and the span between supports. As a general starting point, corrugated single-skin suits closely spaced purlins on carports and sheds, 10 mm twinwall is a common minimum for a walk-under patio or greenhouse roof, and 16 to 25 mm multiwall suits larger spans and colder climates where insulation counts. Thicker panels span farther and insulate better but cost more and can reduce light. Always confirm the maximum purlin spacing on the manufacturer span chart for the exact panel and load.
- Corrugated (single-skin): sheds, carports, walkway roofs with frequent supports.
- 10 mm twinwall: entry-level patio and greenhouse roofs needing some insulation.
- 16 to 25 mm multiwall: larger spans, insulated rooms, colder regions.
- Solid 4 to 12 mm: canopies and glazing where clarity and impact matter.
Common uses for polycarbonate roofing
Polycarbonate roofing fits any structure that needs daylight without the weight or fragility of glass. Its low weight lets it sit on light timber or aluminum frames, and its impact resistance suits hail-prone and high-traffic sites. The most common applications overlap heavily with the panel types above.
- Patio covers and pergolas: tinted twinwall to cut glare and heat.
- Carports and walkways: corrugated single-skin for low cost.
- Greenhouses: opal twinwall or multiwall for diffused, even light.
- Skylights and roof lights: multiwall for insulation, solid for clarity.
- Canopies and entrance roofs: solid clear sheet for appearance and strength.
How to install polycarbonate roofing panels
Polycarbonate roofing installs over purlins or rafters using glazing bars or matched closures, with allowance for thermal movement. Panels expand and contract more than metal, so fasteners never pinch the sheet tight and holes are drilled oversize. Below is the core sequence; follow the specific panel and glazing-bar instructions for spacing and torque.
- Set the pitch. Give the roof at least the manufacturer minimum fall, commonly around 5 degrees, so water sheds and does not pool.
- Orient the UV side up. Multiwall panels are UV coated on one side only; install that marked side facing the sun or the sheet yellows and cracks early.
- Seal open flutes. Tape twinwall and multiwall ends with solid tape at the top and vented breather tape at the eaves so the flutes drain and stay clear.
- Run flutes with the slope. Internal ribs must point downhill so condensation drains out rather than sitting inside.
- Drill oversize holes. Make fixing holes larger than the screw shank to let the panel move; fasten through the crown, not the valley, on corrugated sheets.
- Use cap-washer fasteners. Seat screws with sealing washers to firm contact, not crushed, and set them into glazing bars or purlins per the span chart.
- Finish edges. Cap glazing bars, fit end closures and foam fillers, and leave the protective film on until the last panel is placed.
The mistakes that cause most failures are predictable: installing multiwall with the UV side down, drilling tight holes that split the sheet as it expands, leaving flute ends open so algae and water collect inside, and over-tightening screws until the sheet dimples and leaks. Each is avoidable by following the four points above.
Polycarbonate roofing pros and cons
Polycarbonate roofing trades some clarity and insulation for toughness, low weight, and daylight. It is a strong fit where impact resistance and light matter and a weaker fit where full transparency or a long lifespan drive the choice. A well-installed polycarbonate roof commonly lasts 10 to 20 years, per supplier estimates, shorter than glass or metal.
- Pros: light weight, high impact resistance, good daylight, easy DIY cutting, lower cost than glass.
- Cons: can yellow over time, scratches more easily than glass, single-skin forms add no insulation, expands and contracts a lot, shorter lifespan than metal or tile.
Frequently asked questions
How long does polycarbonate roofing last?
A well-installed, well-maintained polycarbonate roof commonly lasts 10 to 20 years, per supplier estimates, with the UV-coated weather side facing the sun. Lifespan depends on panel quality, tint, sun exposure, and whether the UV side was installed correctly. Cheaper uncoated panels can yellow and grow brittle sooner, while premium coated multiwall at the top of that range holds clarity longest.
Is polycarbonate roofing cheaper than glass?
Polycarbonate roofing is usually cheaper than glass to buy and install. Panels commonly run about $2 to $6 per square foot for material, and the low weight, roughly half that of glass for solid sheet, cuts framing and handling costs. Glass still wins on long-term clarity and scratch resistance, so the trade is lower upfront cost and better impact resistance against a shorter clear life.
What thickness of polycarbonate do I need for a roof?
For most patio and greenhouse roofs, 10 mm twinwall is a common minimum, with 16 to 25 mm multiwall for larger spans or colder climates. Corrugated single-skin suits sheds and carports with closely spaced supports. The right number depends on span between purlins and snow load, so check the manufacturer span chart for the exact panel before buying.
Does polycarbonate roofing yellow?
Polycarbonate can yellow over years of sun exposure, which is why quality panels carry a factory UV coating on the weather side. Multiwall is usually coated on one side only, so installing that marked side toward the sun is essential; fitting it upside down causes early yellowing and brittleness. Coated panels installed correctly hold clarity for much of their 10 to 20 year life.
Can you walk on polycarbonate roofing?
You should not walk directly on polycarbonate roofing panels. The sheets are impact resistant but not designed to carry point loads, and stepping between supports can crack a panel or void a warranty. For access, use a crawl board or ladder spread across the rafters or work from below, and follow the manufacturer guidance for the specific panel.
Corrugated or multiwall polycarbonate: which is better?
Corrugated is better for low cost and maximum light on carports, sheds, and walkways, while twinwall or multiwall is better where insulation and reduced glare matter, such as patios and greenhouses. Corrugated single-skin gives no thermal barrier; hollow multiwall traps air to insulate and diffuse light. Choose corrugated for budget cover and multiwall for a comfortable, usable space beneath.
Reviewed by The Roofing Brief Team. Last reviewed August 2026.