What do I do with crumbling bricks in loft?

[turbojetsilver]

I am in the process of boarding the loft and adding some extra insulation to my ~1900s terraced property. It appears to have had some kind of modification/support made to the chimney stack, and that is what is being supported by this steel RSJ that partially blocks my loft hatch.

Unfortunately, on the wall directly by the loft hatch, there are some very badly crumbling bricks. Others are rock solid. Every time I open the loft hatch, bits of the bricks fall down, especially if it's been a while since I was last up there. Given that there is carpet under the hatch, I have to put down a tarp when I open the loft hatch or else the red brick dust stains the carpet and it is very frustrating.

I have tried applying PVA solution and it held them together a bit but it's still very crumbly and the application of the PVA itself caused even more crumbling in the process. Video attached shows the assortment of crumbling bricks and some tapping on nearby ones to show how solid they are by comparison.

Is there a treatment I can apply to stabilise these properly, maybe a sealant? Or can I just plaster over the top? Or do I need to remove the crumbled bricks and replace them individually? Why is this happening?

Thank you!

 

[foxhole]

Wash over with weak pva mix and glue sheets of plasterboard with fixing foam to give a clean finish .

 

[RrogerD]

It seems a shame to cover up such a fascinating feature. But yes, covering it completely would be you cleanest solution.
For ease use plasterboard as foxhole says but this will still have dust dropping down behind. For stability, have it fully plastered over.
Or, diluted SBR over the whole lot a couple of times. Better than pva as not effected by water. This'll hold the whole lot together.

 

[Ivor Windybottom]

Seconded vote for SBR. Anyone who's ever attempted to remove this stuff knows just how well it bonds.

I have an old cheapo hoover that I have for jobs like this, use the brush nozzle to suck off as much dust as possible first.

I'd also give it a brush with a wet hand sweeping brush in a bucket of water beforehand.

 

[Harry Bloomfield]

I had a similar problem in my loft, but with the mortar, between the bricks. I wanted to emulsion the brickwork, to make it a bit brighter up there. Painting it, loosened the mortar, as I tried to paint. I solved it, and stabilised it, with Thistle finish plaster. I made up a quite watery mix, and applied that all over the brickwork with a wall-paper pasting brush. Left to dry for a day, I was able to paint it.

 

[turbojetsilver]

It seems a shame to cover up such a fascinating feature. But yes, covering it completely would be you cleanest solution.
For ease use plasterboard as foxhole says but this will still have dust dropping down behind. For stability, have it fully plastered over.
Or, diluted SBR over the whole lot a couple of times. Better than pva as not effected by water. This'll hold the whole lot together.

Plasterboard also adds a fair bit to the wall and it is already a tight fit getting things up the loft hatch with the great big RSJ in the way!

Seconded vote for SBR. Anyone who's ever attempted to remove this stuff knows just how well it bonds.

I have an old cheapo hoover that I have for jobs like this, use the brush nozzle to suck off as much dust as possible first.

I'd also give it a brush with a wet hand sweeping brush in a bucket of water beforehand.

Per yourself and RrogerD I might give this SBR a go- thanks. Worth noting though that I did already try to use a vaccum it and the vaccum started taking whole chunks out of the crumbling bricks. It's to the point where I reckon some of those spalled bricks could be removed entirely with the vaccum cleaner - and I'm not exxaggerating!

I had a similar problem in my loft, but with the mortar, between the bricks. I wanted to emulsion the brickwork, to make it a bit brighter up there. Painting it, loosened the mortar, as I tried to paint. I solved it, and stabilised it, with Thistle finish plaster. I made up a quite watery mix, and applied that all over the brickwork with a wall-paper pasting brush. Left to dry for a day, I was able to paint it.

What proportions would you say you used? I assume it must have been thin as anything for the brush marks from application to not be super obvious after painting?

 

[Harry Bloomfield]

What proportions would you say you used? I assume it must have been thin as anything for the brush marks from application to not be super obvious after painting?

Thicker than paint, but thin enough to dip a brush in, then worked well into the mortar gaps - in your case, into the bricks to stabilize them.

 

[stuart45]

I'd prep it like Ivor said and give it a thin parge with a sand/cement/SBR mix.

 

[turbojetsilver]

Thicker than paint, but thin enough to dip a brush in, then worked well into the mortar gaps - in your case, into the bricks to stabilize them.

I'd prep it like Ivor said and give it a thin parge with a sand/cement/SBR mix.

Thanks both for the input. Any advantages of the watered down plaster compared to the SBR before I pull the trigger and buy one of them?

I would say I am reluctant to do a sand/cement parge in the loft - would rather just seal and paint over it if possible as my sole goal here is to have as thin a coating on the wall that doesn't restrict carrying boxes out of the loft hatch, that also prevents further crumbling, dust, and brick degradation crumbling down.

Could there be a hybrid approach here with SBR first, then the watered down thistle plaster (hardwall/bonding?), then some masonry paint?

I am still unclear as to the cause of this whole thing tbf - my understanding of spalling is that is caused by the freeze thaw cycle with water permeation - yet I can't imagine bricks in the loft freezing even if there was any water ingress as the temperatures don't go that cold up there, heat rising and all.

 

[JohnD]

An old house will have had many periods when the loft was frozen.

Modern climate temperatures are warmer than 50 years ago.

And so are houses, mostly having central heating and some of it escapes upwards.

I had one where I tried to apply a stabilising solution by brush, and the brush rubbed the surface off. I ended up using a sprayer and applying a couple of well thinned coats.

 

[turbojetsilver]

An old house will have had many periods when the loft was frozen.

Modern climate temperatures are warmer than 50 years ago.

And so are houses, mostly having central heating and some of it escapes upwards.

I had one where I tried to apply a stabilising solution by brush, and the brush rubbed the surface off. I ended up using a sprayer and applying a couple of well thinned coats.

Interesting but valid point. I wasn't thinking back to the original construction, but instead to how it's currently insulated and heated.

 

[noseall]

Any advantages of the watered down plaster

No. Never.

 

[catlad]

You can buy bags of cement slurry mix which is mixed up to a thick soup consistency, that could be applied by brush. A similar approach to Harry's suggestion but once it started going off it could fill a few of the bigger holes.

 

[Ivor Windybottom]

I'd put a 50/50 mix of SBR/water on first (to encourage it to soak in) then slap a second coat on neat.

It will be like milk on the first coat, cream on the second. It will definitely stick everything together.

My guess would be that they were just rubbish bricks, intended for internal use where they were going to be plastered over.

 

[Ivor Windybottom]

Whether you do or don't put a slurry over it should be decided after the SBR. My bet is it will probably be pretty tough at this point and won't need it, in fact you could create more problems by putting a surface over if this then starts falling off.

But, if you do want to render it then the SBR will be the perfect primer anyway, you've done what anyone rendering a wall should do first anyway.