"Bernie Hunt" wrote
cshenk,

Thanks for the pics Bernie, helped alot. Worked on a house once with a
stairwell that looked much like that. The 'top stringer' that showed was
cosmetic. The real only support member was underneath. We removed it as
it was ugly and warped. Then we put corner molding along both sides.
(the risers were flush to the steps so this wasnt that hard).

Assuming however the 'stringer' isnt cosmetic (since you have a better
view in person, you'd know), then I'd take out the bad wood and cut a
replacement that will drop down and fit, but won't have the one side fit
into the stringer (fill that portion in with something).

Support by strong brackets to the bottom stringer (apply brackets, then
drop stair on them after fitting in at the other end). If the risers are
properly supported, put more brackets on the bottom of the stair. With
careful measuring, you can get a tight 'fit' so the stair doesnt wiggle
(in any direction) and with predrilled holes, you can attach to the lower
riser then cover with some sort of wood putty.

That's the direction I'm headed. Get the old stair out and then brace all
the way around underneath. The left side of the stairwell, when assending,
is a wall all the way to the ceiling. The right side stops at floor level
on the second floor. So people will be looking to the right as the accend
the steps. I'll flll the left side dado so it's flush with the surface on
the stringer. Then I'll cut the new step to fit in the right side dado and
lie on the new cleat on the left side.

The one I showed you will be the easier one, the upper stair has the knwel
post sitting on it. I'll have to look at removing it.

Can you get us a pic of that too then? Hey, the camera might not be perfect
but it works well enough and it's what you have. Perhaps we'll have some
workable ideas for you but have to see the post and railing.

I liked the idea of the riser access too but only if you are real sure there
isnt a support member behind it. Then again, I figured you had to remove a
stair tred anyways, so the riser access might be more work?

Tap carefully with a hammer (rubber mallet works better) all along the tops
of several stairs (healthy ones as well as bad ones) from left to right. If
there's a fairly consistant sound difference at some spot, usually middle,
then you have a 3rd structural stringer that you couldnt see because of the
plaster underside. There's good reason for it too as it's underside makes
the lath frame the plaster may have been attached to. It may *not* be in
the center. Say they had a bunch of that lath frame wood in scrappy form
that was 2 ft long (left over from some other part of building the house).
Stairwell looks like it's abut 3. Might be you find a 3rd support stringer
2ft from one side and about a foot on the other. Harmless and easy to tap
along several steps to see if you can tell something is there before you
open anything up.

I wish I had a picture to show you of what the underside might be since it's
plastered. Generally the frame that was plastered has a support frame with
I think it's no more than 18 inches. Similar to studs in a wall then cross
pieces you plastered. Methods varied with age of house. wikipedeia look
for lath and plaster.