Deck Stairs Footing

[mattradk]

It's probably a minor issue, but what is usually specified for footings or supports for the end of deck stair stringers where they meet the ground (soil)? The area I'm interested in is upstate NY where the frostline is usually assumed to be 48", so there is an annual freeze/thaw cycle.

I've seen 4" termite blocks placed under each stringer, a 4" concrete slab supporting the stringers, 6" sonotubes under each stringer reaching down 48", treated dimensional lumber placed flat on the ground and screwed to the stringers, and nothing at all.

Thanks!

 

[phamENG]

I live in a more moderate climate so freeze/thaw is a consideration, but rarely a key driver in design. Will the rest of the deck's foundations bear below frost? If so, the stair foundations should as well. I'd probably go for a sonotube on either side where the guardrail posts land and span across to pick up the stringers if you can make it work. If it's an especially wide stair, you may need some intermediate foundation eleemnts.