How to Straighten Warped Stair Stringers

Anyone know of a good method to straighten/pull a warped stringer off of wall so 1x10 stair skirt will fit?

 

You'll have to remove or unscrew the treads. Then just pry the stringer over.

 

Yes i know i need to remove the temporary treads. There isnt much to pry against except the sheet rock. I'll try and wedge some ply wood in and pry it over a little at a time maybe that will work.

 

After you remove the treads lay a 2x4 diagonally on top of the stairs so it spans across several studs and pry on that. Slip a shim down behind the stringer such as a couple pieces of 1/2" plywood if you need 1"... or one piece of 1/2", one piece of 3/8" if you need 7/8". And put a screw into it so it can't fall out. Then repeat on the next one.

Once both sides are shimmed in the right amount, you could fasten a temporary tread back on top to hold them there and then remove the screws and remove the shims so that you can drop your skirt down in the gap.

Usually you have a diagonal board permanently fastened to the wall that provides the right amount of space between the wall and stringer so your skirt board can just sit on top.

 

I've also used shims. Put a thin piece of something against the sheetrock to protect it. I use a scrap of sheet metal but luan or thin plywood can also work. Then you can drive a wedge between your protective sheet and the stringer.

You can also use a ratchet strap. Attach one end to the part of the stringer you want to move. They attach the other end to one of the other stringers. This method generally works if you don't have to pull too hard but it's nice because it doesn't require touching the walls.

If the stringer is annoying and keeps wanting to spring back you can block it in position after you've pulled/wedged it out. I use a small scrap of wood the right thickness to hold the gap. Position your spacer block down at least several inches so you can start your stair skirt. Then as you slide the skirt board into place let it push your temporary blocks out.

 

Thanks for the suggestions. There is a 2x4 running diagonally up like Sleeper mentions but for whatever reason it stops on that one side right where the bow starts. The other side it runs all the way up and there is no issue.
I think I'll try the ratchet straps first and see if I can get some leverage pulling against the other stringers. If that wont work I'll try prying it a bit at a time and wedging spacers. Ive got some large nail plates so may i can use that to protect the drywall as I dont want to mess that up. I'll post a photo of success or if I f'up!
The other problem I have is I cant seem to find skirt material in a 14ft length so I guess I'll have to join a 12 footer to a 2 footer but I dont have a biscuit joiner so that will be fun too!
Thanks again for the suggestions. FF

 

Unless the stairway walls are a constant width. at the steps location, top to bottom and the stairs a constant width, top to bottom, any skirt installed will have gaps, stair to skirt. Have you considered a skirt that is cut to match stair rise and run? Looks like a reversed stringer. Stairs would need to be anchored to one wall shimmed to have equal max gaps on each side of stairs. Skirt thickness would be the max gap or thicker.

 

Be careful not to snap off the cut portion of the adjacent stringer. A nailer across several stringers to anchor the ratchet strap would be better.

 

That's a good point... as 2john02458 suggests, you could break the stringer along the grain of the wood so don't pry on the tips of the stairs... (the point of each triangle). The lower you pry the better.

And then fasten something temporarily across each step to hold them together so they can't spring back toward the wall when you remove the shims.

 

Don't be afraid to check locally owned lumber yards and contractor suppliers for longer length boards. My tiny town has a big box home center AND two privately owned lumber yards that have bigger selections and better prices.

 

Small towns will be different but in most good lumberyards (not box stores) the standard length will be 16 ft. And it may be engineered like MDF or have a veneer. But it's certainly available. And if they don't have it they can order it.

 

I was very leery of breaking that stringer nose as some you mentioned so...the wedge idea worked well!
I removed the top three treads and blocking at the top of the stairs and was able to access the stringer from the unfinished garage level under stair area (I have some leftover foam ins. board there). I could then drive a firewood splitting wedge up between the stringer and drywall/framing and move it over.






On another note.... Im planning to use pine risers/treads because everything else is so dam expensive.
Would there be any benefit to box in the stairs with OSB then install the risers and treads? Im thinking it would make stairs more solid and I'd have a continuous surface to glue to.
Thanks for all the advice!

 

Code says that no step on a staircase is suppose to vary from any other step by more than 3/8". It creates a trip hazard. So if you add onto the top of your stringers you would be changing the rise of the first and last step. Once the treads are on, they should all be the same, that includes the landing.

Putting osb on bottom (last photo) would help keep the stringers together and prevent them from warping / bending when you take your splitting wedge out.