Do Stair Stringers Need Support?

Yes, the stringers need to be supported along their length, but they can span a few feet too, depending on 1) the width of the stairs, 2) the number of stringers, and 3) size of riser board. 1) The wider the stair the more load will be transferred to the stringers.

How do I support a stair stringer?

You should attach 2x6 or 2x8 support framing under the rim flush to the bottom of the stringer. The stairs will hang here. Install a piece of blocking below the rim joist to extend the attachment surface for your stairs stringers. Use a level to mark the top step.

How long can stringers be without support?

The minimum recommended size for a deck stair stringer is 2x12, which has a maximum recommended unsupported span of 6 feet. Often this maximum span is dangerously exceeded, resulting in overspanned stringers that will deflect and cause the connection at the deck to pull loose and fail.