Want to build a wood deck with circular stairs?

Question

Only about 4' off the ground, and only about a 7 foot wide deck, with a 3' wide stairs. Is it easy to make a circular stair for a deck, and how. I have built plenty of decks before.

Answer 1

I'll quote paragraph R311.5.8.1 of the 2006 International Residential Code (IRC):  "Spiral stairways are permitted, provided the minimum width shall be 26 inches with each tread having a 7 1/2 inches minimum tread depth at 12 inches from the narrower edge.  All treads shall be identical, and the rise shall be no more than 9 1/2 inches..."

On this basis you'll need five steps plus the top landing.  Assuming that the narrower edge is 6" from the center of the spiral, the stairs would go through approximately 1/3 turn.  However, if you have a larger inside radius of 12", the stairs would make a quarter turn, which would be a better configuration for putting the stairs at the end of the deck.

The footprint for these spiral stairs would be a quarter circle with a radius of 48" if you have a 36" tread width.  This compares with a footprint of 36" by 72" for conventional stairs.  In my opinion, if you have the room, conventional stairs are easier to build and use.