Damp timber & stairs / New floor problems

[Mike]

Hi, Loads of good advice given in old thread about the concrete flooring I'm laying. Just run into a problem area I hadn't thought of though: Our 'project' has no ground floor to speak of, just tiles on soil - very damp. DPC has just been done and I'm now laying new floors with damp proof membrane, but have realised that there is a section under the foot of the stairs which I can't access because there is a small wall at the back of the under stairs storage area (not sure if this is structural support for the staircase) Question is, do I just lay concrete flooring up to the foot of the staircase and stop or should I start dismantling the stairs for access? I fear the answer is going to be removing the stairs because the whole point of the new floor is to get rid of the damp and the stairs are pretty soggy & spongy at the bottom. I'm clueless as to how to tackle this so any advice on removing and refitting/replacing would be much appreciated (as would book / website recomendations). I'll also need to know if removing the bottom couple of steps renders the rest of the staircase unusable because we are living upstairs at the moment! Obviously if anyone can come up with a less disruptive plan, that would be even better : ) Going off on a bit of a tangent, all ground floor joinery is suffering from some sponginess / rot at the base for a couple of inches (has been checked - no dry rot thankfully!). Skirting and architrave is being replaced but does anyone know if it's possible to treat and/or fill the existing doorframes, or is it a rip them out and start from scratch job? I'm assuming this is a complicated and expensive job best avoided if at all possible? Thanks for reading.

[meow2222]

You'd best stop and ask at

NT

[Roger]

The message from "Mike" contains these words:

You need to do the whole floor if you want to cure the damp but you may not need to dismantle the stairs. The wall might be there just to provide an end stop. If the wall is the support for a quarter landing the landing will need support before you take out the wall but if it is a straight flight I think the stringers should be pinned to the walls and even if that is inadequate you should be able to give the stringers alternative support while you demolish the wall and dig out beneath the foot of the stairs.

[Mike]

Thanks for the advice Roger. I was just thinking, I may not have described the situation too well though. The wall I'm talking about is only a stubby little thing and is only preventing access to the bottom two or three of steps. I could probably manage the job if I removed just a couple of risers or treads but I'm not sure how to tackle this as the stairs have a wall either side ('closed' I think is the correct term)? Also, not knowing anything about how structural support works in staircases, I wanted reassurance that doing this would not affect the strength of the rest of the stairs - we need to use them while the work is being done as we live on the second floor.

[Roger]

The message from "Mike" contains these words:

You don't say whether it is a straight flight or a turner but either way it is unlikely to matter with such a low wall. AIUI with a straight flight the stringers are supported by the ground floor and and also fixed to the adjacent walls if the walls are strong enough. But the wall fixing doesn't seem essential as you can have free standing flights although it will make a significant difference in your case whether or not the wall fixings are there at all or are strong enough to retain the stairs in their rightful place when the ground is removed.

With an enclosed stair you may not have a newel post at the bottom of the stairs but if you have there is at least the possibility that the bottom end is sunk into the floor. I don't know how important that is should the damp have led to the sunken portion rotting.

From what you say I would have thought the wall is there only to block off an awkward shaped cavity that can't usefully be used for anything but I could be wrong. Just remember that on Usenet no advice is ever guaranteed and go cautiously as you demolish the wall and particularly as you excavate under the bottom of the stringers. You will have to play it by ear when it comes to supporting the stairs while there is a hole underneath but if you have to prop the treads from below prop both sides as close as possible to the stringers and if you are at all doubtful prop the next step as well. I assume you would want to start with props as low down as you can get.

Unless the stairs are of a very peculiar construction you will not be able to remove either riser or tread from the outside without destroying them and would need access to the underside to replace them. Depending on how well they have been glued, nailed and wedged in removing them with access to the underside may be no easy task but at least with access to the underside you would be able to fit replacements.