Plasterer wants to replace plaster with boards & plaster

[CluelessDIYer1]

Had someone out to look at our damp issue. We'd been advised to patch replace the plaster.
Plasterer came out to assess the work & advised against patching in as it may sort the damp, but it may not & if it doesn't then we'd be back to square 1, just higher up the wall. It was agreed that the wall would just get re-done.

It's been the Mrs who's dealt with this chap & at 11pm on a Sunday we can't be asking him, so i thought i'd see here if anyone could make sense of this...

He mentioned putting in 13mm plasterboards & then skimming & dotting & dabbing (terms are lost on me!). I work for a builders merchants & know no 13mm boards, so i assume he meant 12.5mm.

For one i'm not sure why he's planning on using boards anyway. Right now it's plaster on there (with some fine hairs in it - so i'm assuming original stuff). I assumed anyone would just go like-for-like & plaster it. 12.5mm boards will pad it all out quite a bit & probably result in us needing new skirting.
Which makes me wonder - why 12.5mm board & not 9.5mm board? & how'd you fix these things to a wall without battens padding it out further?

I'd started removing some of the stuff myself:


A lot of it came away extremely easily. I'm getting to the stage now where it's more of a challenge to remove.
The grey plaster on the lower half is actually sound. There's no damp there at all & that stuff is bloody tough. Crowbar didn't really want to know about it. I'd assume leave it, but if boards are getting used then surely this would have to go also. Just wondering - why create work?

Don't know how thick that stuff is but seems reasonably thick:




What do you reckon to this?

As i say, the Mrs has dealt with this chap so i can't really get in touch with him at the moment. It's just something that was getting me thinking today - why the boards, why not just plaster, why 12.5mm & not 9.5mm. I know boards will allow for an easier smoother finish, but then that's creating work by surely needing to remove the sound lower half?

 

[NickB_99]

Looks like the tough grey bit at the bottom, may be a render (sand and cement) with a waterproofer in it to try to control the damp coming through.
It looks newer then the original plaster.

I would tend to agree with you to replace like with like and not use boards.
You are correct, standard sizes 12.5 or 9.5mm thick.
Most using boards prefer the 12.5, as they are more sturdy.

I would think you have a higher success rate if any patching is to be done, it is done with render. If the remainder is loose, then best to take it off and float a new undercoat against the level of the solid lower part. Re skim the wall.

Note - I'm only a diy er and there are some unknowns here for me - is your damp an ongoing problem? There seems darkening on bricks above the lower, but is this because you'd just taken some off there or these bricks are damp?
Is the property old - hair in the original indicates and older plaster, but is it lime?
Some of the pros may be able to help you better than me here.

 

[stevethespreader]

if that wall has or has had damp problems the last thing you want to do is dot and dab it, if the lower half has been damp proofed and is sound with no damp I would take all the top off and float it all in with sand and cement and reskim the whole lot, are you skimming the ceiling as well? if so float the walls in then scrim the edges between the ceiling and wall skim the ceiling then skim the walls

 

[CluelessDIYer1]

No the ceiling isn't getting done.

I'm not quite sure what they're going to do exactly. I know they're 'tanking it'. They have 9.5mm boards there instead of 12.5mm. They've chipped the sound grey plaster off the lower half on the worst wall to the left of chimney but as of last night had patched in on the right side of the chimney (better wall). I thought they were going to do the entire wall.

Still not sure why youd replace plaster with boards+plaster. I thought like-for-like?

 

[NickB_99]

I'm not quite sure what they're going to do exactly. I know they're 'tanking it'. They have 9.5mm boards there instead of 12.5mm. They've chipped the sound grey plaster off the lower half on the worst wall to the left of chimney but as of last night had patched in on the right side of the chimney (better wall). I thought they were going to do the entire wall.

Still not sure why youd replace plaster with boards+plaster. I thought like-for-like?

It may be too late now, but I would suggest you need to be made aware exactly what they are going to do/have done.
What did they do on the right of the chimney? Was it patched in by using an undercoat plaster (e.g. Bonding) or render (sand & cement) or even by cutting sections of their 9.5mm boards to fit the gaps and dot&dab to secure them? I really hope it wasn't the last option.
Have they skimmed the whole wall for you afterwards?

Like for like is a sensible assumption.
but the discussion really for what they are planning, was perhaps at the quoting stage.
Like for like with what you have requires undercoat plaster to be applied (called a float and set). This is more labour intensive and would probably attract a higher quote.
Now they have probably purchased materials and are probably nearly done.
I suspect they have cleared the entire left hand wall ready to cover the whole with the boards.
12.5mm boards are generally preferred as they are more substantial. Cost-wise - 9.5mm boards are about 25p cheaper, so not much in it.

Where I have used D&D it has gone straight onto block/brick, I've not ever tanked underneath. Some suction is needed for the drywall adhesive, I hope the tanking doesn't affect this.
Probably a question for the pros on here...

 

[CluelessDIYer1]

but the discussion really for what they are planning, was perhaps at the quoting stage.

At that point the chap certainly said 13mm boards. I remember this because i work for a builders merchant & remember thinking i've never seen 13mm boards in all my time there, so he must mean 12.5mm. Then when we went down last night they were 9.5mm.

I'm sure (although not as 100% as with the 12.5mm bit) that he also said they'd be doing the entire top half of the right side of the chimney & not just a patching in job.

The wife called to find out whether they were certainly tanking it & they said yes they were bringing that stuff today.

I'll have to bob through when i get the chance & put them on question time as to why the seeming change in approach.

 

[NickB_99]

At that point the chap certainly said 13mm boards. I remember this because i work for a builders merchant & remember thinking i've never seen 13mm boards in all my time there, so he must mean 12.5mm. Then when we went down last night they were 9.5mm.

I'm sure (although not as 100% as with the 12.5mm bit) that he also said they'd be doing the entire top half of the right side of the chimney & not just a patching in job.

The wife called to find out whether they were certainly tanking it & they said yes they were bringing that stuff today.

I'll have to bob through when i get the chance & put them on question time as to why the seeming change in approach.

Ah yes, had forgot that bit about the 13mm boards from the first part.

Before they go on, you can probably discuss this with him.
Though I'd try not to go in all guns blazing - there's no substitute for face to face communication to iron out any misunderstandings.

Good luck.