On Aug 10, 9:56*pm, stratford1 wrote:
I'm building a set of stairs on my deck and CANNOT seem to find a
straight answer on this. I'm using closed outside stringers spaced 36"
and will use metal tread brackets to attach two 2x6 treads for each
stair. Some info I've found says I DO need a third stringer in the
middle for support...others have suggested I DO NOT need a third
stringer as long as my span isnt longer than 36". *Any suggestions on
this? Will my 2x6s hold up ok or should I do the third stringer
regardless to make my stairs stronger?

So why are you debating using one? The cost of adding a third
stringer is minimal and you already know in your mind that without it,
it will be 'springy'.

Add the third stringer. It won't need any fancy cleats, etc, just cut
to fit under the treads.

Harry K