How to plaster over hole in wall after having central heating pipes moved?

jt1413

We've just had our central heating pipes chased into the wall in our lounge. 

The engineer has done the best he can but as it's an external wall couldn't go too deep as there is breeze block behind. 

How do I now plaster the wall? As you can see in the pics there isnt enough room for plasterboard to fit in the gap.

Advice on materials and methods really appreciated! 

grumbler

jt1413 said:

The engineer has done the best he can but as it's an external wall couldn't go too deep as there is breeze block behind.

Has he? The block can be easily chiselled too.

How do I now plaster the wall? As you can see in the pics there isnt enough room for plasterboard to fit in the gap.

How much place is it actually? How deep are the pipes?

You can try using cement board that starts from 6mm IIRC.

ETA: in fact it can be as thin as 3mm, e.g. https://www.ashbrookroofing.co.uk/fibre-cement-strips-1200mm-x-150mm-x-3mm.html

neilmcl

Fill the bulk of the gaps with a bonding coat leaving it below the surface of the plaster then fill over that with a fine filler, such as Easifill and sand down.

fenwick458

grumbler said:

jt1413 said:

The engineer has done the best he can but as it's an external wall couldn't go too deep as there is breeze block behind.

Has he? The block can be easily chiselled too.

the max depth you can chase the wall is 30mm for a 100m block wall.

I'd do as neilmcl has described, but use dry wall adhesive instead of bonding. it's much more resistant to cracking when the pipes heat up. also if it's dot and dab boards that have been cut right through floor to ceiling it will give the wall a bit more strength too

FreeBear

fenwick458 said: the max depth you can chase the wall is 30mm for a 100m block wall.

1/3 the wall thickness for vertical chases, 1/6th for horizontal. So a nominal 30mm vertically, and 16mm horizontally, plus the thickness of the plaster.

Copper pipes must be well protected from the corrosive nature of plaster. My preference is to sleeve 15mm copper in 20mm plastic conduit. This allows the pipes to expand & contract without any annoying clicks, creaks, or bangs. And no buried solder joints !

twopenny

"This allows the pipes to expand & contract without any annoying clicks, creaks, or bangs"

Just stopped me worrying so much about mine FreeBear.

jt1413

fenwick458 said:

grumbler said:

jt1413 said:

The engineer has done the best he can but as it's an external wall couldn't go too deep as there is breeze block behind.

Has he? The block can be easily chiselled too.

the max depth you can chase the wall is 30mm for a 100m block wall.

I'd do as neilmcl has described, but use dry wall adhesive instead of bonding. it's much more resistant to cracking when the pipes heat up. also if it's dot and dab boards that have been cut right through floor to ceiling it will give the wall a bit more strength too

Thanks for the advice, I'm only just getting round to actually doing the job so hence a very late reply.
Is this the adhesive you mean?
And i just shove it in all the gaps down the edge of the pipes, and then easifill over the top yes? The section is floor to ceiling. I'm relatively well versed at filling holes but not when they're this big and central heating pipes are involved!

fenwick458

yeah thats it, and yes thats right. 
the drywall adhesive isn't very sandable, so don't go mad with it. I normally wipe the edges of the chase with a wet cloth afterwards to get as much of it off as possible