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Apprentice answer

What's the difference between a canted curb and a flat curb

3rd YearRoof Curbs, Louvers & Exterior AirCheck first

Canted Curb: Features a raised, angled built-in wooden or metal triangular cant strip along the bottom perimeter. This allows the roofing material (like modified bitumen or built-up roofing) to transition smoothly up the side of the curb at a 45 ∘ angle to shed water.

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Plain-English answer

Canted Curb: Features a raised, angled built-in wooden or metal triangular cant strip along the bottom perimeter. This allows the roofing material (like modified bitumen or built-up roofing) to transition smoothly up the side of the curb at a 45 ∘ angle to shed water.

Flat Curb: Has a straight 90 ∘ vertical base. It is designed for single-ply membrane roofs (like TPO or EPDM) where the roofing sheet can be rolled directly up the vertical wall of the curb and tucked under a counter-flashing cap.

Field checklist

Ask Foreman

Hey boss, I’m checking roof work & curbs: What's the difference between a canted curb and a flat curb? I found the likely issue and want to verify the next step before I lock it in. Do you want me to adjust it now or check the drawing/detail first?

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Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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