My deck stairs which are supported by ledger strips keep pulling away the stringer. Last year I used a clamp to squeeze them back together but they pulled away again. The railing also is wobbly. What would be the best way to fix the stairs so they are more stable?
Flexing tread working on those minimal supports. that is a wide span for any tread. even with standard stringers cut I would have one in the center– KrisApr 12, 2019 at 20:39
Do you know where I could find good instructions on how to add a middle stringer to pre-existing stairs?– MarcApr 12, 2019 at 23:10
Hard to tell whether you have screws or nails holding everything together right now. It is either nails - which can, relatively easily, come apart, or screws which can come apart but not as easily.
If you have nails then I would reinforce using some long (e.g., 3") screws and you should be set. I would want two screws into the end of each tread. The railing is sometimes a bit trickier, but screws to supplement the existing nails is a good start. If that doesn't take care of all the wobbling of the railing then you may need to replace parts or add some additional supports. Of course, if you find any cracked or rotted pieces, or if anything cracks when you drive in screws, then you need to replace those pieces.
If you already have screws then I'd be a bit more concerned as that may be a sign of the wood rotting (and therefore not holding the screws any more) or that there is just too much movement of the ground causing everything to come apart.
It is nails holding it together. I will try the screws. The railing is more difficult, I'm not completely sure where I would drive the screws in, possibly from the outside of the posts.– MarcApr 12, 2019 at 20:53
From the picture it looks like both stringers are easily accessible. Just drive screws straight through the stringers into the treads. Apr 12, 2019 at 20:57
Misread your comment. Rail posts could be trickier. Screws at an angle may work. Apr 12, 2019 at 21:33
Screws are a good idea.
Another fix that also would help vs flex would be to put a 2x4 under each step, oriented so the 2 inch side is up against the bottom of the step. Attach the 2x4 to the step and the ends of the 2x4 to your stringers.
I would scout the neighborhood for scrap 2x4s for that use. If you are going to buy new wood, replace that splintery looking top railing with the nice new 2x4s and use that old railing wood for under the steps.
1I advise against scouting as you are unlikely to find pressure treated; I recommend buying a PT board. Apr 13, 2019 at 15:50