Wall repair prep pre decorating

[Mrs Pingu]

There are several patches like this above the 'skirting' going up the stairs. They flex a lot. Although I have been reading recently about repairing cracks with Fill Flex and Toupret Fine scrim tape, with fine filler on the top, there is such a lot of flex here I don't think it will work.
Is this likely to require cutting big chunks out and screwing board in there?

PXL_20240129_191836563 by The Pingus, on Flickr

[aidan.f]

Problem is the stair casing has been glued to the wall plaster with paint and filler. It's always going to move and crack again unless you stop using the stairs!

[Mrs Pingu]

This evening's YouTube viewing suggests cutting a big gap between the plaster and the stringer (apparently) and using expanding foam (ugh) to fill the void between the stringer and the wall and the plaster and the wall so it doesn't flex so much, and then use filler over that.
Though none of the videos I watched had the cracks coming quite that high up the plaster.

[Asterix, the former Gaul.]

Problem is the stair casing has been glued to the wall plaster with paint and filler. It's always going to move and crack again unless you stop using the stairs!

I used frame sealant in 2020 when decorating the hall/stairs/landing.  No cracks, I just looked!  You have to use the right stuff or it's difficult to paint.

[Mrs Pingu]

Having looked at this again recently, I reckon someone has already tried to 'fix' this by putting a strip of quadrant/moulding along the top of the stringer, so I guess it's going to be all sorts of shit behind there now it's all glued together with multiple layers of shit paint, which is presumably why the cracking is creeping so far up the wall like that.

I did wonder if I could perhaps just hide the issue in future by removing that quadrant and getting some bead board (?) panel fitted between the stringer and the handrail. What does the panel (ha!) think? (Apart from the fact it'll look crap if I don't then get it put all along the hall too.)

By the way if anyone likes watching someone prep stuff to death you might enjoy @TheOfficialGRB on X. Extreme cornice stripping.

[Mrs Pingu]

This is where I'm at today.
PXL_20240421_135604524 by The Pingus, on Flickr

Friday I was thinking about removing the quadrant, but had started to think that was a bad idea by the end of the day.
Today I decided to strip all the paint off the top of the stringer and quadrant to get a better look. The quadrant in the photo above still has a trail of paint on it in this photo til I get a scraper with the right profile.
Now I've tidied up, I've just been inspecting the gap with a torch and a straight edge. If I lie the straight edge down the wall I can see that the bottom of the plaster has been built out by quite a lot to meet the edge of the quadrant. That seems like a frikkin stupid idea.

Anyway, what I'm thinking now is I should remove that quadrant, make good the plaster so that it is flat to below the top of the stringer (this will be several mm behind the stringer) and when that's all dry, get a new, thicker bit of quadrant and glue it to the wall (so that it's not really in contact with the stringer.

Thoughts?

[robgul]

A drawing of the issue in "section"  would be useful to see exactly what you have going on.

Assuming I'm understanding what it might be, I had a similar issue in a vry old house - I removed the quadrant moulding from the stringer and fitted one that was almost the width/thickness of the stringer, pushing against the plaster I had made good down almost to the stringer.

[Mrs Pingu]

? I've somewhat exaggerated the bend between flat wall and quadrant but hopefully you get the idea.
PXL_20240421_180709583 by The Pingus, on Flickr

[robgul]

Hmm - first off if the gap is variable and the staircase/stringer flexes I'd make sure there's nothing structural going on that needs fixing - perhaps some hefty fixings from the stringer on say every 3rd step into the wall - it looks like blockwork - to stabilise it ... which may possibly pull the staircase closer to the wall??

Unless a bodge with a large quadrant and caulk is acceptable - and you don't want to hear this - I'd look at stabilising the stringer and getting the whole wall skimmed (Unibond the existing wall before plastering)  to a proper flat surface up to and square to the stringer - and then fit a quadrant pinned to the stringer and caulked onto the new plaster.

[Russell]

Do you have fine dust in your understairs cupboard?  We do and our stairs are pretty much similar to yours.

[Mrs Pingu]

Do you have fine dust in your understairs cupboard?  We do and our stairs are pretty much similar to yours.

No, but it's all boarded/plastered off so you can't actually see the undercarriage of the stairs.

[Mrs Pingu]

Although it didn't look that bad I started stripping the paint off the other side tonight. Really I'm just fiddling about, putting off the inevitable ripping off the plaster quadrant...
It's ok, the decorator isn't coming for another month.

[Mrs Pingu]

So I was thinking about replacing this 10mm quadrant with 15mm quadrant to hide the gap a bit once I've done the filling. But that's not going to work when I get to the horizontal bit here which isn't deep enough to take 15mm quadrant.
PXL_20240419_151559263 by The Pingus, on Flickr

Any fantastic ideas? (Besides knock the house down and start again)