Should I knock it all off...?

the_black_pearl · Post by **the_black_pearl** » Tue Sep 10, 2019 6:37 pm

Hi guys,

You all know how a small job turns into a big one. I started out wanting to re-wallpaper a bedroom, and, well, here I am in the plastering forum.

After stripping the wallpaper I noticed a few big cracks in the plaster. The house was built in the 60s and I've noticed various spots in the house where the plaster seems a little crumbly, and assumed that I would need to get the whole lot redone at some point. I hoped I could fill the crack so started to make it bigger with a stanley knife, but noticed that it was just coming away in my hands. I then started to knock the wall in various spots and it seems that it's blown (I believe that's the correct term!) I removed a big chunk of it to expose the brick / breeze underneath, though it was only about 1cm deep (is that normal?) In terms of the breeze / brick...my understanding is that it's all breeze, and the brick section I think is a filled in chimney breast. I need to take away more plaster to confirm this. It does seem that the blown parts are mostly over the brick rather than the breeze.

Anyway, my question....I'd rather avoid pulling the whole lot off if possible. Should I continue to pull the bits that are clearly not attached to the wall? If so I thought I could "dot n dab" some plasterboard to the brick in the missing section, then smooth over the joins and finally wallpaper with some of that thick wallrock stuff. Or, given the age of the house, should I just bite the bullet and knock the whole room off? If the latter is the best option then I will be attempting to do the whole lot myself, so again, plasterboarding it all and then wallpaper on top.

I have attached some images.

I await your years of collective wisdom! Oh and if you could speak in layman's terms that would be great, I'm an absolute novice when it comes to this type of thing!
Thanks.

dewaltdisney · Post by **dewaltdisney** » Tue Sep 10, 2019 7:03 pm

Did you use a steamer to strip? This can often result in blowing the plaster like seems to have happened here. Plastering in the 60's would have been a cement based scratch coat and the finish plaster coat. The best way to repair is to remove all the blown areas and get a plasterer in to fix it. He will put a bonding coat on to bulk up the void areas and then a finish to get it all level.

You might be able to do the bonding yourself but it is best to get a plasterer in to finish.

DWD

OchAye · Post by **OchAye** » Tue Sep 10, 2019 7:26 pm

I think you will knock it all off or near enough. The 2nd photo shows the plaster not being in touch with the bricks. If you tap the plaster and it sounds hollow then you know ... :-( Other than that do as Dewalt suggests, you might even want to find a plasterer before you continue with the demolition ... errrm decorating. You will have to wait for probably 2-4 weeks for the plaster to dry before you try to decorate. Don't accept to have it covered with plasterboard (dot and dab).

London mike 61 · Post by **London mike 61** » Wed Sep 11, 2019 7:11 am

I would knock the whole lot off and either get it plastered or dot and dab plasterboard. Be aware that if you want to fix anything to the wall with dabbed plasterboard then you will have to use corefix fixings because normal wall plugs won’t hold in the wall, you won’t have this problem with a gypsum plastered wall.
Just things to consider

Mike

Rorschach · Post by **Rorschach** » Wed Sep 11, 2019 11:34 am

You can see from the pics the whole wall looks to be blown. Take it all down and either re-plaster or board it out. Personally I think I would board it, it could be that the specific circumstances in your property mean that the walls do not readily hold onto plaster and you could have a similar problem again.

the_black_pearl · Post by **the_black_pearl** » Wed Sep 11, 2019 6:01 pm

Cheers for the replies all.

I've gone knocking around the whole room and it doesn't sound like anywhere else is blown. In fact I've taken a bit more back on the right hand side and it seems that the only loose bits are over the brick (bricked up chimney breast). The bits over breeze seem fine. With this in mind I'm leaning towards just trying to repair this part.

I've measured the depth and it's between 9-11mm, which I think means that board is out since the existing level isn't deep enough?
I may try and do the bonding bit myself to fill in, and I'm not too fussed abo the finish as it will be papered with wallrock.

dewaltdisney · Post by **dewaltdisney** » Wed Sep 11, 2019 7:07 pm

If you do plaster it yourself paint a diluted watery PVA on and let it dry. Next day paint over again with the PVA mix before applying the bonding coat. Bonding is used to bulk out the void, get it on and level it off about 2mm below the surface to allow for the finish coat to bring it level. The PVA stops the wall sucking the water out the paster and it becoming unworkable very quickly.

DWD

Deleted-user-3 · Post by **Deleted-user-3** » Sat Nov 09, 2019 5:21 pm

Use thistle hardwall as opposed to bonding coat..
Bonding is designed for low suction..
that wall will suck like crazy...
Id still give it weak pva before then get straight on it with a wetish mix of hardwall..
The you need something straight and using the edge of the existing plaster as a guide rule off the hardwall
let it go almost right off then rub it with a plastic float just to close it in...
top tip after that is paint the entire wall with stabilising solution and let that dry before giving it a quick pva then skim the whole lot...
stick some scrim (plasterboard joint tape) over the cracks before you do this though, scrim wont stay put on wet pva or stabiliser..
the stabiliser will soak into the plaster and sort of lock it all together a bit like using wood hardener on rotten timber..
if it was a solid 9" wall id say sand and cement only as a backing plaster but cant see any headers so must be a cavity wall?