Good afternoon all. I have a set of straight run stairs that IÃ¢â‚¬â„¢m replacing, and I have a pretty good handle on the overall construction, but there are a couple fine points IÃ¢â‚¬â„¢m fuzzy on.
The stairs IÃ¢â‚¬â„¢m making have housed stringers and closed risers. Rise is about 7-1/2 and run is around 9-10 inches (I donÃ¢â‚¬â„¢t have the drawing in front of me), with a tread width of 37-1/2 between stringer faces. The stringers are 2×12 syp and will be shimmed and screwed to studs, risers are 4/4 poplar, and treads are 6/4 (1-1/4 finished) #1 common white oak. ItÃ¢â‚¬â„¢ll be stained treads with painted risers & stringers. Treads and risers will be rabbetted and grooved, then screwed together as well, wedged and glued into the stringers.
Now for the questions: I believe this width of stairs requires a third stringer according to code, but with the treads and risers glued and screwed, does this eliminate the need for the third stringer? I saw an earlier comment of Stan FosterÃ¢â‚¬â„¢s regarding the extra strength added by gluing and screwing the treads and risers together (http://forums.taunton.com/n/main.asp?webtag=tp-breaktime&msg=24264.1). There are some occasional knots in some of the treads, but they’re 6/4 stock, so I figure they should be okay with the closed risers. If it’s questionable, I can add a center stringer. The current stairs are open riser with 2x syp treads, no center stringer. They visibly deflect.
I figure washer head screws would be better than flat heads (#10 okay)? With the joints glued, does it really matter? With a housed stringer and wedges, should I screw into the end of the treads and risers through the stringer, or is that pointless?
Is epoxy reasonable? Or will it not have enough initial tack for the wedges, since itÃ¢â‚¬â„¢s kind of slippery? The stairs are for a basement that stays dry year round, but you never know, right? The wedges will be made from offcuts from the treads, but should they be cut across the grain so they match the tread movement? I intend to finish the pieces all around before assembly (except of course the glue surfaces) to try to minimize expansion and contraction.
Sorry this is so long, and hopefully I havenÃ¢â‚¬â„¢t asked anything too stupid, but stairs being what they are, I want to make sure theyÃ¢â‚¬â„¢re as strong and stable as possible. And if you got this far, thank you, I appreciate your attention.