Polycarbonate thickness guide - solid, twin-wall and triple-wall sized right
Picking the right polycarbonate thickness for patios, skylights, machine guards and ballistic glazing - with span and load tables.
Polycarbonate is forgiving - but oversizing it wastes money and undersizing it cracks. Here's how the trade picks thickness for the four most common applications.
Patio and pergola roofing
For domestic patios with rafters at 600–900 mm centres, 8 mm twin-wall polycarbonate carries snow and wind loads across Australia and most of New Zealand. For exposed alpine sites or larger spans, step up to 10 mm or 16 mm triple-wall.
Solid polycarbonate at 4–6 mm is overkill for most patios but is the right call when you need crystal-clear visibility (verandahs and pool covers).
Machine guarding
Australian Standard AS 4024 calls for 6 mm solid polycarbonate as the baseline for fixed machine guards against low-velocity impact. Step up to 8 mm or 10 mm for higher-energy hazards (grinding, lathe chips).
Skylights and barrel vaults
10 mm or 16 mm multiwall polycarbonate is the standard skylight build. The cellular structure delivers an R-value comparable to single-glazed window units while shedding hail that would shatter glass.
Security and ballistic glazing
12 mm solid polycarbonate resists hand tools, hammers and most thrown objects. For rated ballistic glazing (P6B and above under EN 1063) you laminate three or four layers totalling 30–50 mm.