In your opinion are those stairs gone and need replacing?

[Matt723]

I have a likely original (~1905) staircase above a cellar which like a lot of cellars is damp (rh 75%+). Removed the lath plaster to fix creaks after reading for weeks on this forum on how to fix however it seems there is structural damage on the stringer on the brick wall side (the other stringer looks okay considering the age).

The issue is that under about 3 stairs the beetles tunnels are so advanced that the wood has split and the wedges fell on their own, there is nowhere to put them back. Additionally the stair case does not seem attached to the wall, so it could be that this stringer will fail in time compromising the whole stair case.

I note there are 3 joists going under the staircase, I am not sure what they are here for, only one joist (nearest to the wall) has the treads resting on it, the other are not touching everywhere and even can be moved by hand.

Keen to hear your experienced opinions on this one:
1. Does this staircase need replacing? If not how would you fix this string which is eaten by beetles?

2. If replacing any advice on wood to use above damp cellar to prevent this again over time? Or even steel if this is a thing?

3. Do I need to investigate for wood beetles elsewhere (e.g. landing on top of stairs, joists on ground floor)? I am concerned it would involved lifting many carpets, boards and be an invasive procedure.

4. If the stairs need replacing, how one normally deals with 2m height requirement? Current dimensions are ~ 160mm risers and ~220mm treads thus fine (just) with with current reg. However have a step with 1.91m head clearance whilst 2m seems required (the step where the above joist / plaster is in place).

Thanks a lot

 

[Notch7]

it doesnt look that bad to me.............Ive seen way worse repaired on listed buildings


the string will have been fixed with nails.

the treads and risers look good mostly, Id say its quite possible to repair it

You need to make sure the woodworm damage is historic and not current -clean off all the old frass, dust and debris then monitor and see if you get any new appearing


You dont necessarily have woodwork everywhere -they prefer wood with over 20% mc, so in places where the wood is damp like cellars, against damp walls etc

 

[Matt723]

Thank you Notch.

The part that worries me is the string on the side of the brick wall that is effectively decomposed and if the whole side of the stair relies on having a sound string from top to the bottom if it cracks in the middle there will be trouble I guess. Additionally I am unsure how to go about repairing this without dismantling the stairs since that string is stuck between the stairs and the brick wall. If I am missing something do let me know, still taking it all in.

Re woodworm I went ahead and removed the fireproof plasterboard attached to the ground joists and was pleased to see they don't look "bored".
Even the joists in the landing of the cellar basement (right behind the cellar door from the corridor of the house) seems fine, and it is really strange because the floorboards resting on those joists have been attacked (see photos). Thus so far the problem does seem contained to the stairs and it's puzzling as to why, but not complaining! I have cleaned and will do the test you recommend to see if new frass appears.

I need to sort some ventilation in there but it will be a little project as it's fairly contained, might need power socket for dehumidifer and even extractor fan of the bathroom or kitchen type.

Again any insight from the experts very gratefully received re next steps

 

[Matt723]

Update, we now believe the string has already failed and this is the reason why steps on that side of the stair case are resting on the underside rafter (they steps are not touching the other two rafters in the middle and near the opposite stringer).

We are not finding a way to strengthen or support that damaged stringer near the brick wall and replacing it altogether would mean dismantling the stairs, in which case we might as well just put some new in...

The alternative would be to use the underside rafter as a new stringer, by screwing some solid wood on it and wedge it under the steps. Do you think is acceptable and could work?

Thanks!

 

[blup]

That should work but infill the gap.

 

[Matt723]

Thanks blup, what do you mean by infill the gap? The gap between the tread above and the block? with PU glue?

 

[blup]

In the last pic, there appears to be a difference in levels between the triangular area (between the tread and riser), and the joist you are fixing the block to. It may just be the pic