Rendering over old chimney

[John Rraymond]

Hey guys, going to work in a house where the chimney breasts have been removed, they were back to back. left with a single skin brick wall which now separates two bedrooms. Both sides, there are black soot marks that run from floor to ceiling. The builder suggested cover that particular area with mesh make up a 3:1 render mix, to help put strength back in the wall, add some water proofer to stop the soot marks bleeding through. Any thoughts please,

John ( new plasterer)

 

[Dr.B]

I think a building control notice is needed there for sure!

 

[Pug]

You'll need to scrub as much of the soot off as possible as it'll bleed through even with waterproofer in the mix. Also 3:1 is too strong a mix and would be prone to cracking imo.

 

[John Rraymond]

Thanks Pug, what about the idea of using the mesh?
John

 

[Dropsalot]

Thanks Pug, what about the idea of using the mesh?
John

Mesh is for a good key, only as good as the fixing method. @Deri might be right, building control might need to put their spoke in re the single brick skin.....structure might be compromised by taking out cheeks of the chimneys.
@imago??

 

[Deleted member 23452]

It definitely needs building control approval. Are the bedrooms in the same house? It sounds like that's what you're describing, in which case once building control have seen it they will let you know what's needed structure wise. If the chimney's are between two houses then there should have been a notification to the neighbour and a party wall agreement in place.

Mesh and render will add about as much strength as gluing your underpants to the wall. If it's weak then it'll need raking and pointing.

What's above the wall? Is it in the centre of the house? If it is and the roof truss braces point down towards it then it's a spine wall and it needs to be strong enough to take part of the roof loading.

 

[John Rraymond]

Thanks for the advice, the structural side of it has all been done,there is enough steel up in the loft space to make a battle ship, the wall is just now
separating two bedrooms ( in the same house) didn't want to go off at a tangent about the structural side, just wanted some advice on the rendering side
of things.
Thanks,
John

 

[Dropsalot]

Thanks for the advice, the structural side of it has all been done,there is enough steel up in the loft space to make a battle ship, the wall is just now
separating two bedrooms ( in the same house) didn't want to go off at a tangent about the structural side, just wanted some advice on the rendering side
of things.
Thanks,
John

Ok mate, as @Pug says, get the soot off as it will bleed through. Scrape, brush, clean and clear it then seal it with either sbr or similar (we all have different preferences), then fix the mesh and render it out. I personally would scratch coat the wire and leave it a day before floating out, then skim it next day. Others may differ. Good luck.

 

[John Rraymond]

Ok Dropsalot thanks, would you still put a water proofer in the mix for one or both coats.

John