Problems with Plaster Board

[speedchick]

Hoping someone can help my other half.

A few years ago he had his loft plasterboarded and plastered, waited the required time, pva'd the walls and then painted over it. (As told to)

Went in his loft the other day and it seems that the skim has cracked along the lines of the boards, so he has perfectly straight horizontal and vertical cracks, almost like the boards have shrunk ever so slightly, also in one area the paint is peeling off, almost like its dried out too much and is coming off the wall.

So two questions, what does he do about the paint peeling, and also what does he do with these cracks, what should he fill them with and will they come back.

I don't know much about plaster and plasterboard, and neither does he, so we are hoping someone can help.

Thanks

[mrmaggit]

Sounds like shrinkage cracks, but could be movement cracks.

How much does it bother you? The reason I ask is that really the answer is to re-scrim over the cracks, then re-skim with plaster.

Is it really worth it given that it's in the loft, and non-structural?

[Busamav]

as Mr maggitt says .

Did they use moisture resist boards as the loft sees extremes of temperatures and conditions ?

Edited by Busamav on Tuesday 21st December 09:06

[speedchick]

I don't know what they used, it's not my house, but I do know that he wants to use the room for his model railway, so the area will be used.

Thanks for the info, will pass it on to him.

[Simpo Two]

It's only a loft, I'd just paint over it.

[VxDuncan]

Well the joints should have been taped. If not they will crack. The temps/humidity may also do this as stated. The other thing is the walls shouldn't have been PVA'd post plastering - PVA isn't waterproof and any humidity can cause paint problems.

I think it's a simple case of movement/shrinkage.

[B17NNS]

Why were the Walls PVA'd?

A mist coat (50/50 water/emulsion) over new plaster followed by a couple of coats of neat emulsion over new plaster is the correct method.

When the boards were skimmed the jointed should gave been taped (covered with fibreglass mesh scrim tape). If this wasn't done that is the problem.

Scrim taped joints still crack occasionally but it is massively reduced.

As said I would assume it is due to movement of shrinkage.

As an initial soultion I would score down the crack to enlarge it, fill with polyfilla, sand and repaint.

If the cracks appear again I would fill with caulk and repaint.

Caulk remains slightly flexible so should allow a little movement without cracking.

[Spudler]

Agree with the above two posts, especially re the PVA
Would also suspect a lack of fixings, noggins and quite likely just one skim of plaster.

[speedchick]

He said PVA'd not me, when he wakes this evening I will ask him about it, (currently snoring his little heart out in his truck) just to make sure he is clear on what he did to them. I did think he had water/emulsioned them, but it's not my house so I wasn't there to oversee it.

Will inform him of what you have all said and send him to B&Q on Friday for filler/tape/whatever else

[dickymint]

Was scrim tape used? Or was it "dry-walled" then plastered?

[GG89]

dickymint said:

Was scrim tape used? Or was it "dry-walled" then plastered?

Either way scrim tape would have to be put over all plasterboard joints and internal corners to stop cracking at the joints. Sounds like the "plasterer" *cough couch* hasn't put scrim over the joints before skimming.

[speedchick]

Spoke to him last night, asked about the tape and he doesn't recall seeing the guy put any on, I also asked about the PVA and he said that's what he was told to use, I think he watered it down.

Obviously he's now not happy that the job wasn't done right, and he says that he can't afford to have it all re-skimmed, so he's going to take on the advice from here and try and make it good.

Thanks everyone for your help

[dickymint]

GG89 said:

dickymint said:

Was scrim tape used? Or was it "dry-walled" then plastered?

Either way scrim tape would have to be put over all plasterboard joints and internal corners to stop cracking at the joints. Sounds like the "plasterer" *cough couch* hasn't put scrim over the joints before skimming.

That's what I was alluding to - no tape. I've seen this done many times. (indeed my own ceilings have all cracked due to lack of tape. I'm pretty sure that original dry walls didn't use tape, just filler.

Speedchick:

If they used proper dr-wall boards they will be tapered at the joins to allow for filler (or filler and tape) . You may be able to scrape out the joints to allow tape to be applied and re-scimmed at the joints only. Pain in the arse but should be possible. I would try this out inside a cupboard and see.

Good luck.

Edited to add: With a new Stanley blade and a straight edge, score the board vertically either side of the cracked joint to a depth of about 5mm at a width slightly wider than the scrim tape. Then carefully try and scrape/chip out the joint.

If the loints are butted and not tapered I've found a couple of useful vids on Youtube.

http://www.youtube.com/watch?v=s62-wP1viUg&fea...

I've never seen this stuff before (spray over tape) but looks easy for a DIYer

http://www.youtube.com/watch?v=UKRXAI15KmI&fea...

Edited by dickymint on Wednesday 22 December 09:22

[GG89]

dickymint said:

GG89 said:

dickymint said:

Was scrim tape used? Or was it "dry-walled" then plastered?

Either way scrim tape would have to be put over all plasterboard joints and internal corners to stop cracking at the joints. Sounds like the "plasterer" *cough couch* hasn't put scrim over the joints before skimming.

That's what I was alluding to - no tape. I've seen this done many times. (indeed my own ceilings have all cracked due to lack of tape. I'm pretty sure that original dry walls didn't use tape, just filler.

Speedchick:

If they used proper dr-wall boards they will be tapered at the joins to allow for filler (or filler and tape) . You may be able to scrape out the joints to allow tape to be applied and re-scimmed at the joints only. Pain in the arse but should be possible. I would try this out inside a cupboard and see.

Good luck.

Edited to add: With a new Stanley blade and a straight edge, score the board vertically either side of the cracked joint to a depth of about 5mm at a width slightly wider than the scrim tape. Then carefully try and scrape/chip out the joint.

If the loints are butted and not tapered I've found a couple of useful vids on Youtube.

http://www.youtube.com/watch?v=s62-wP1viUg&fea...

I've never seen this stuff before (spray over tape) but looks easy for a DIYer

http://www.youtube.com/watch?v=UKRXAI15KmI&fea...

Edited by dickymint on Wednesday 22 December 09:22

Im not sure what you mean by 'Original Drywall' when drywall was introduced as a quicker alternative to hard plastering/Lath and plaster it was specified to have 'Lath boards' and then later mesh scrim over joints, whether it be tape and filled or skimcoated the joints need to be covered by a mesh of some sort to stop cracking.

[dickymint]

GG89 said:

dickymint said:

GG89 said:

dickymint said:

Was scrim tape used? Or was it "dry-walled" then plastered?

Either way scrim tape would have to be put over all plasterboard joints and internal corners to stop cracking at the joints. Sounds like the "plasterer" *cough couch* hasn't put scrim over the joints before skimming.

That's what I was alluding to - no tape. I've seen this done many times. (indeed my own ceilings have all cracked due to lack of tape. I'm pretty sure that original dry walls didn't use tape, just filler.

Speedchick:

If they used proper dr-wall boards they will be tapered at the joins to allow for filler (or filler and tape) . You may be able to scrape out the joints to allow tape to be applied and re-scimmed at the joints only. Pain in the arse but should be possible. I would try this out inside a cupboard and see.

Good luck.

Edited to add: With a new Stanley blade and a straight edge, score the board vertically either side of the cracked joint to a depth of about 5mm at a width slightly wider than the scrim tape. Then carefully try and scrape/chip out the joint.

If the loints are butted and not tapered I've found a couple of useful vids on Youtube.

http://www.youtube.com/watch?v=s62-wP1viUg&fea...

I've never seen this stuff before (spray over tape) but looks easy for a DIYer

http://www.youtube.com/watch?v=UKRXAI15KmI&fea...

Edited by dickymint on Wednesday 22 December 09:22

Im not sure what you mean by 'Original Drywall' when drywall was introduced as a quicker alternative to hard plastering/Lath and plaster it was specified to have 'Lath boards' and then later mesh scrim over joints, whether it be tape and filled or skimcoated the joints need to be covered by a mesh of some sort to stop cracking.

I meant - I'm pretty sure originally drywalls did not use tape. I've seen many walls without tape, some with hessian, some with paper or fibreglass.

Anyhow as you and I know, these days tape is a pre-requisite.

I refer to dry-wall as bevelled plaster board filled with whatever, sanded down and painted on (no plaster skim coat).

PS. Just finished (my boss and I ) our first fully lime rendered and plastered listed building. Had to keep the original laths etc. And to be honest apart from the length of time to do, found it much easier/satisfying to do than using cement.

[mrmaggit]

I wouldn't go to that much trouble, tbh, it's a loft, being used to contain a model railway. Why not wallpaper over it?