Plastering Advice

[RMS]

Hi all,

I have recently removed some old tiles from my bathroom wall and want to plaster the wall back up. The tiles were half way up the wall and allot of them have taken the top layer of plaster off.

I think the backing coat is browning. It is grey in colour and seems quite powdery when i rub it. It is firmly attached to the wall. I am wondering what the best type of plaster I can use to plaster it back up. I am going to get a pro in the skim the whole lot when I have done it.

I don't want to remove the plaster because it will be too much work and the blocks are thermolite. House was built in 70s.

Any help appreciated.

 

[trowelmonkey1]

sounds more like render than browning to me, and friable at that! you could use some wickes plaster bonding agent to stabilize the friable render before attempting to plaster.

if all that has happened is that the skim coat has come off in places then the plasterer should be able to sort that with an overskim in my opinion, would recommend getting the tile adhesive off the walls though, coating them with the WBA i mentioned above and just to make sure a sealing coat of PVA 5:1 (5 water:1 PVA) to kill any remaining suction.

plasterer should love you for it, tricky to know if you need to fill out walls without seeing but doesn't sound like it.

 

[RMS]

Thanks for the reply.

The tiles were well stuck on so the back coat has come off quite deep in places, Also I have stripped out some cables and a copper pipe that were chased in the wall back to the block.

I am thinking of treating the wall with the bonding agent as you suggested and bonding it back level before it gets skimmed. Is bonding the best plaster to use for this?

 

[NickB_99]

sounds more like render than browning to me

Are there backing & finishing plasters that are/were in grey?
I'm sure what I have in my place sounds very similar. (circa early 70s, so same age). I didn't think it was render.

If it behaves the same as my stuff (so long as still adhering to block work underneath) came up great with a dose of PVA/water applied to it 24 hours before. Turned something quite crumbly into a much better substrate.
Then PVA/water as normal just before and apply Bonding to fill in the gaps has done me well.

 

[roughcaster]

Yes,,, i'd go for bonding plaster if there are deeper areas to fill, but to be honest, as TM says, the plasterer would really want to sort it out himself.

Roughcaster.

 

[roughcaster]

Most gypsum based backing plasters over the years have been grey.
As an aside,,, does anyone remember Carlite Metal Bonding Coat plaster,,, used for plastering onto wire lath??

Roughcaster.

 

[trowelmonkey1]

carlite before my time having said that i went into my local merchant yesterday to get multi as i'd found out they sell it and keep it out of sight, was mooching around the shelves and came across bags of carlite bonding

 

[Micilin]

Most gypsum based backing plasters over the years have been grey.
As an aside,,, does anyone remember Carlite Metal Bonding Coat plaster,,, used for plastering onto wire lath??

Roughcaster.

Was it "Metal Lathing" - if so used loads of it in hospital rib lath ceilings. Was it a purple or blue bag????? Presumable the mad variety of plasterboards did away with it

 

[NickB_99]

TM1, you mentioned Wickes Plaster Bonding agent. Not used before.

Naive question time..... how does this differ from PVA/water?

The Wickes site described the Plaster Bonding Agent as 'Aggregate loaded polymer based coating'. Does this mean it has got sand or some small size 'granules' in there to help the next coat to stick to?
(perhaps even similar to R/C's suggestion of bonding in PVA/water mix from a while ago?).

 

[roughcaster]

Most gypsum based backing plasters over the years have been grey.
As an aside,,, does anyone remember Carlite Metal Bonding Coat plaster,,, used for plastering onto wire lath??

Roughcaster.

Was it metal lathing

It could have been called that Micilin. I cant remember the colour of the bag though,,, but i know it was used just for working onto metal lath.

Roughcaster.

 

[trowelmonkey1]

Hi Newbie!

Yes it's got small aggregate the size of sand in it, red in colour so easy to see where you covered, great easy solution for low/no suction backgrounds and will sort out friable surfaces like powdery render etc.

on the down side, it's quite expensive and won't kill high suction backgrounds on it's own, needs help from PVA too.

having said this, on the upside it dries quite quickly, says 2-4 hours on the tub but i've found it's more like an hour to two, no need to worry about timing, i.e. waiting until tacky, and has a great mechanical key, i'm finding i'm using it on artex ceilings these days followed by a PVA sealing coat, seems to work a treat.

does the same as RC's method all said really, but i think he only does that when applying a tight coat of bonding afterwards as the key you would have from using bonding coat would be quite lumpy, too much so for just skimming unless you go back over it and knock off anything too high for skim to cover.