Subject: Octagon deck
Name: R.M.
Who are you: Other

I am building an octagon deck and I want to know what length to cut the outside boards.The overall is 12ft. wide.

Hi,

Not too long ago we received the same question from Martin but his octagon was 2.5 feet in width. Sue answered and showed that for an octagon of width w the length x of a side is given by

x = 0.4142w

Thus in your case where w = 12 feet

x = 0.4142 12 = 4.97 feet.

I would cut the boards 5 feet long.

Penny