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Client wants deck boards laid diagonal — expansion gap math?

K
Kevin Doyle

Have a client set on a 45-degree diagonal layout for their Ipe deck. My standard 3/32" gap is based on 5-1/2" face width, but on a diagonal the effective width across the gap changes. Do you gap based on board face as usual, or adjust for the diagonal? Also assuming I need 16" OC joists instead of 24" for diagonal spans — confirm?

3 Replies

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Ben Sutherland

Gap stays based on face width — movement is across the grain regardless of layout angle. And yes, 16" OC: your effective span at 45 degrees is your joist spacing times 1.414, so 24" OC becomes a 34" span. Way past spec for 1x Ipe.

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Grant Ellison

Also budget 15% extra material for the diagonal waste. Clients never expect that number.

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Megan O'Brien

Megan O'Brien here. Gap stays on the face — 3/32

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