What Thickness Polycarbonate Sheet Do You Actually Need? A Buyer Decision Guide
“What thickness polycarbonate do I need?” is the first question almost every buyer asks – and it is also the one that causes the most over-spending. Too thin and the panel flexes, yellows, or cracks on impact. Too thick and you pay double the material cost plus freight and installation weight. This guide gives you a direct thickness-by-application table so you can specify the right RP polycarbonate (PC) sheet on the first RFQ.
Quick Thickness Reference Table
| Application | Minimum Thickness | Recommended Thickness | Notes |
|---|---|---|---|
| Machine guards (low impact) | 3 mm | 5 mm | General machine protection |
| Machine guards (heavy impact) | 8 mm | 10-12 mm | Chip containment, high-speed tools |
| Skylight / roof glazing | 4 mm | 6-10 mm | Depends on snow/wind load |
| Window replacement (home) | 3 mm | 4-6 mm | Impact-resistant glazing |
| Greenhouse / patio cover | 4 mm | 6 mm twin-wall | Multi-wall for insulation |
| Security glazing (Level 1-2) | 12 mm | 15-20 mm | Monolithic ballistic PC |
| Bullet-resistant (Level 3+) | 40 mm | 40-75 mm laminated | Multi-layer ballistic laminate |
| Sound barrier wall | 12 mm | 15-20 mm acrylic | See our noise barrier guide |
Three Factors That Change the Answer
1. Span and Support
A 4 mm PC sheet on a 600 mm span is fine for a machine guard. The same 4 mm sheet on a 1.5 m span will deflect under snow load or foot traffic. Rule: if the unsupported span exceeds 1 m, add at least 50% to the recommended thickness.
2. Impact Load
Polycarbonate is 250 times stronger than glass by weight, but not infinite. For chip containment (CNC, lathes), use 8 mm minimum. For pedestrian walkway glazing, 10-12 mm is the safe specification. For ballistic applications, you need a certified laminate – not a thicker monolithic sheet.
3. UV Exposure
Standard PC yellows in 2-3 years outdoors. If the panel faces direct sun, specify UV-co-extruded PC (RP uses a 50 micron UV cap) regardless of thickness. Thicker stock does not solve UV degradation.
Common Mistakes
- Buying 20 mm “just to be safe” for a machine guard – overspending 3x.
- Using monolithic PC where a laminate is required – a 40 mm solid PC is not a UL 752 Level 3 panel.
- Ignoring the masking film – never leave protective film on after outdoor installation; it bonds to the surface.
Get the Right Thickness for Your Project
Tell us your application, panel size, expected impact load, and climate. RIVER PEOPLE PLEXIGLASS (RP) manufactures cast and extruded acrylic and polycarbonate sheets from 1 mm to 100 mm, and we will recommend the most cost-effective specification rather than the thickest one. Request a thickness recommendation.
Related: Bullet-Resistant PC Buying Guide | Browse PC Sheets
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