Polycarbonate Roof Calculator

Calculate polycarbonate sheet quantities, purlin spacing, R-value, and total cost for patio covers, greenhouses, sunrooms, and pergola roofs by area, panel thickness, and profile type

Calculate the number of polycarbonate sheets needed based on roof area and panel size

Quick presets

sq ft
ft

Coverage Area

211 sq ft

Polycarbonate Panels • $632 – $1,686

Estimated Cost Range

$632 – $1,686

PRO

Professional Calculator

Extended parameters for precise calculations

sq ft

Estimated Materials

60 bundles

Roof Area

1,792 sq ft

Squares

17.9

Detailed Breakdown

Roof Area1,792 sq ft
With Waste1,971 sq ft
Roofing Squares17.9
Bundles60
How to Use This Calculator
The Polycarbonate Roof Calculator helps you estimate the number of multiwall polycarbonate sheets, connectors, closure tapes, and total cost for patio covers, greenhouses, sunrooms, carports, and pergola roof conversions. Unlike the Skylight Calculator (which covers individual skylight units) or the Greenhouse Calculator (which addresses full greenhouse structures), this tool focuses specifically on polycarbonate roofing panel quantities and structural support requirements.

Sheets tab: Enter the total roof area to be covered and select the panel thickness based on your application — 6mm for light seasonal covers, 10mm for standard patio covers and greenhouses, 16mm for sunrooms and four-season use, or 25mm for insulated sunrooms in cold climates. Choose the panel width (48 inches is standard) and length to match your roof slope dimension. Select the tint based on your light and heat requirements — clear for greenhouses, opal for diffused patio light, bronze or grey for heat reduction. The calculator determines the number of panels including waste allowance.

Structure tab: Select the purlin spacing appropriate for your panel thickness and local snow/wind loads. Choose the panel connector type — aluminum H-channels are standard, snap-lock bars offer the best weathertight seal, and polycarbonate H-connectors are the budget option. End closure tape (solid at the ridge, perforated vent at the eave) is essential to prevent moisture and algae from entering the multiwall channels. Select your roof slope — the minimum is 1/12 for water drainage.

Cost Estimate tab: Choose DIY or professional installation, and whether you need a new support structure or are covering an existing frame. The calculator produces a breakdown of panel costs, connector costs, closure tape, structure costs if applicable, and installation labor adjusted by your state.

The Formula
The polycarbonate roof calculator uses these formulas:

Panel Count Net coverage width = Panel Width - Connector overlap (1.5 inches per side) Panels needed = ceil(Roof Area x Slope Factor x (1 + Waste%) / (Net Coverage Width/12 x Panel Length)) Slope factors: 1/12 = 1.00, 2/12 = 1.02, 3/12 = 1.03, 5/12 = 1.08, 8/12 = 1.20

Connector Lengths Number of joints = Panels - 1 (for rows of panels across the width) Total connector LF = Number of joints x Panel Length (along the slope) Add perimeter edge channels: 2 x Panel Length + Roof Width for U-channels at edges

Closure Tape Top tape (solid): Panels x Panel Width = total inches / 12 = LF Bottom tape (vent): Panels x Panel Width = total inches / 12 = LF Tape rolls are typically 1 inch wide x 108 ft

Purlin Count Purlins per row = ceil(Panel Length x 12 / Purlin Spacing) + 1 Total purlin LF = Purlins per row x Roof Width

Material Cost 6mm panels: $2-$4/sq ft 10mm panels: $3-$5/sq ft 16mm panels: $5-$8/sq ft 25mm panels: $8-$12/sq ft Aluminum H-channel: $2-$4/LF Snap-lock bars: $4-$8/LF Polycarbonate H: $1-$2/LF Closure tape: $10-$20 per roll

Installation Labor Professional: $3-$8/sq ft depending on complexity New aluminum frame: add $8-$15/sq ft New wood frame: add $5-$10/sq ft State multiplier applied to all labor
Example Calculation
Example: Patio Cover — 200 sq ft, 10mm Clear Twin-Wall, DIY Installation

Sarah wants to cover her 10 ft x 20 ft patio in Phoenix with polycarbonate roofing attached to an existing wood pergola frame. She chooses 10mm clear twin-wall panels for maximum light with decent heat insulation.

Step 1: Panel Count
• Roof area: 200 sq ft, slope 3/12 (lean-to off the house)
• Slope factor: 1.03, adjusted area: 200 x 1.03 = 206 sq ft
• Panel size: 48" wide x 8 ft long, net coverage: 45" (allowing for H-channel overlap)
• Coverage per panel: 45/12 x 8 = 30 sq ft
• Panels needed: ceil(206 x 1.10 / 30) = ceil(7.55) = 8 panels

Step 2: Connectors & Closures
• Panel joints: 8 panels across 20 ft width = 7 joints between panels
• H-channel connectors: 7 x 8 ft = 56 LF of aluminum H-channel
• Edge U-channels: 2 x 8 ft sides + 20 ft eave = 36 LF
• Closure tape: 8 panels x 48" = 384 inches = 32 LF each of solid and vent tape

Step 3: Material Cost (DIY)
• 8 panels x 30 sq ft x $4/sq ft = $960
• 56 LF H-channel x $3/LF = $168
• 36 LF U-channel x $2.50/LF = $90
• Closure tape: 2 rolls x $15 = $30
• Screws and washers: $45
• Total materials: $1,293

Summary: Covering a 200 sq ft patio with 10mm clear polycarbonate panels on an existing pergola frame costs approximately $1,300 in materials for a DIY installation. The 10mm panels provide R-1.7 insulation and 82% light transmission, turning the pergola into a weatherproof outdoor living space while still allowing natural daylight. Annual cleaning with mild soap and water will maintain clarity for 15-20 years.

Frequently Asked Questions

How long does a polycarbonate roof last?
Quality polycarbonate multiwall panels with UV-protective co-extruded layers last 15-25 years before noticeable yellowing or loss of impact strength. Premium brands like Palram SunTuf, Polygal, and Suntop carry 10-year warranties against yellowing and light transmission loss, with effective lifespans of 20+ years in moderate climates. The UV-protective layer on the sun-facing side blocks 99.9% of harmful ultraviolet radiation that causes degradation. Without UV protection, uncoated polycarbonate yellows and becomes brittle within 3-5 years. The primary failure modes are yellowing from UV exposure (install with the UV side up), impact damage from hail, and structural failure from exceeding snow load capacity. In hot climates like Arizona or Southern California, panel lifespan may be reduced to 12-18 years due to extreme UV exposure and thermal cycling. In northern climates with heavy snow, ensure adequate purlin spacing and slope to prevent ponding snow loads that can crack panels.
What is the R-value of polycarbonate roofing compared to glass?
Polycarbonate multiwall panels offer insulation values ranging from R-1.5 for 6mm twin-wall to R-3.5 for 25mm five-wall panels. For comparison, single-pane glass is approximately R-0.9, standard double-pane insulated glass is R-2.0, and low-E double-pane glass is R-3.0-3.5. A 16mm triple-wall polycarbonate panel (R-2.5) provides better insulation than standard double-pane glass at a fraction of the weight and cost. The 25mm five-wall panel (R-3.5) approaches the performance of low-E glass without the weight — polycarbonate weighs about 1-1.5 lbs per square foot compared to 6-8 lbs per square foot for double-pane glass. This makes polycarbonate ideal for large-span roofs where the weight of glass would require significantly heavier and more expensive structural framing. However, polycarbonate has lower optical clarity than glass and does not offer the same noise insulation.
Can polycarbonate panels handle snow loads?
Polycarbonate multiwall panels can handle moderate snow loads when properly supported with correct purlin spacing. A 10mm twin-wall panel on 24-inch purlin spacing can support approximately 15-20 PSF of uniform snow load. A 16mm triple-wall panel on 24-inch spacing handles 30-40 PSF, and on 32-inch spacing about 20-25 PSF. A 25mm five-wall panel on 36-inch spacing supports 25-35 PSF. For reference, most of the northern US experiences ground snow loads of 20-40 PSF, while mountainous areas can exceed 60-100 PSF. In heavy snow regions, use thicker panels, closer purlin spacing, steeper slopes (5/12 or greater to promote snow shedding), and consider adding a mid-span purlin to reduce the unsupported span. Never allow snow to accumulate beyond the rated load — polycarbonate will sag, then crack without warning unlike glass which shatters audibly as a warning.
How do I cut and install polycarbonate multiwall panels?
Cut polycarbonate panels with a circular saw using a fine-tooth carbide blade (80+ teeth) or a specialty plastic-cutting blade at high speed. Support the panel on both sides of the cut line to prevent vibration and chipping. After cutting, blow out the internal channels with compressed air to remove chips and dust. Seal the top edge with solid aluminum tape and the bottom edge with perforated vent tape before installation. Pre-drill screw holes 1/16 inch oversized to allow for thermal expansion — polycarbonate expands about 1/8 inch per 3 feet of length for every 30 degrees Fahrenheit temperature change. Use screws with neoprene washers and do not overtighten — the washer should compress slightly but the panel should not dimple. Leave 1/8 inch expansion gap in all H-channel connectors. Install panels with the UV-protected side facing up (usually marked with a printed label or blue protective film).
Is polycarbonate roofing cheaper than glass for a sunroom?
Polycarbonate roofing is significantly cheaper than glass for sunroom and greenhouse applications. A 16mm triple-wall polycarbonate roof costs $5-$8 per square foot for panels plus $2-$4/LF for aluminum connectors, totaling approximately $10-$18 per square foot installed. An equivalent double-pane tempered glass roof costs $25-$50 per square foot for the glass panels alone, plus $15-$30/sq ft for the heavier aluminum framing required to support the glass weight, totaling $40-$80 per square foot installed. For a 300 square foot sunroom roof, polycarbonate costs approximately $3,000-$5,400 while glass costs $12,000-$24,000 — a savings of 60-75%. The trade-off is that polycarbonate has lower optical clarity (you cannot see through it crisply like glass), a shorter lifespan (20 years vs. 40+ years for glass), and lower resale value perception. For most patio covers, greenhouses, and three-season sunrooms, polycarbonate offers the best value.

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