New plaster coming away - advice sought

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n2248679

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Hi – looking for some professional opinions on this.

· Entire bedroom plastered approx one month ago.
· Mist coat applied last weekend (approx 50/50 Crown Matt emulsion to water, well mixed – pictured)
· After first coat chunks of plaster (2-3mm thick) started coming away from one wall (see pics)
· No damp was visible throughout the room at any point (before or after - and roof space has since been inspected for damp).
· The problem has only occurred on the exterior wall (but I’m monitoring the rest)


Had a builder round last night for an unrelated job, he has some experience of plastering and suggested that PVA was not used (he suggested that this was visible from the exposed plaster).

Plasterer has agreed to come back to resolve this week.... Thoughts (extremely) welcome.


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The plaster has not keyed... It could be isolated areas most probably the whole lot.... Has pva been used? If so has it been applied correctly?
 
Was it a re-skim and if so onto what?
If it was onto a painted surface,a gritted bonding agent should've been used..........PVA should only be used in plastering to control suction,not to provide a 'key'
 
if your builder says it was not uni bonded, do you know what plaster the plasterer used, has the dreaded uni finish struck again :RpS_scared:
 
Was it a re-skim and if so onto what?
If it was onto a painted surface,a gritted bonding agent should've been used..........PVA should only be used in plastering to control suction,not to provide a 'key'

Not correct, PVA has been used by tens of thousands of spreads over many years on paint to very good effect. I'd guess that 80% still do.
 
Was it a re-skim and if so onto what?
If it was onto a painted surface,a gritted bonding agent should've been used..........PVA should only be used in plastering to control suction,not to provide a 'key'
Pva is a man made key and is also used to control suction and has been used as such for donkey's years, the New pre grits also provide a mechanical key which makes them better, nothing wrong with Pva in the right situations but to be honest I am always using pregrit.
 
I do remember the days before blue grit and yes we managed well enough.....we even used to use water to kill suction :-? Like many of you guys we were taught to score the area to be skimmed and either damp down or unibond....by the way I'm not saying the modern blue grit and similar are no good because I do think they have there uses but so does pva.
 
I don't know how some people don't use grit ? Did a test on a painted wall today and after 30 mins the pva still just sat on the surface piss wet.... So the Plas prime came out of the van..
 
Still this fascination with f'kin PVA on everything lingers on.
Times have moved on pal.
You've got your opinion,I've got mine which is PVA on high suction and pre-grit on low-moderate suction paint & artex...........leave it at that shall we?
 
Still this fascination with f'kin PVA on everything lingers on.
Times have moved on pal.
You've got your opinion,I've got mine which is PVA on high suction and pre-grit on low-moderate suction paint & artex...........leave it at that shall we?

1, I'm not fascinated with PVA, I've used grit for years where needed.

2, Yes times have moved on but PVA still works fine and bonds to paint just fine.

3, Your opinion is incorrect in essence. If PVA was used here correctly then quite simply it wouldn't have shelled like in the pictures.

After you've been here a while you'll learn that it's better sometimes to admit that you are wrong instead of digging the hole deeper. :)
 
This looks like the 'reskim' has been applied on top of fresh plaster of some sort.....not backing plaster, but may be my eyes!

Did the plasterer apply a base coat of plaster first? To me, it looks like the skim coat has been applied to a polished finishing plaster?

If the plaster was applied to a cured plaster background, a single coat of pva will not have been sufficient to control suction and if pva was dry when applied, may not have helped the situation.

Regarding the grit or no grit argument.....I ain't used grits for ages, after the fad went away still got 2 tubs in the garage! Just ain't got the time to use it and if you prep surfaces correctly and/or use pva correctly there's really no need unless you wanna drag a job out!
 
This looks like the 'reskim' has been applied on top of fresh plaster of some sort.....not backing plaster, but may be my eyes!

Did the plasterer apply a base coat of plaster first? To me, it looks like the skim coat has been applied to a polished finishing plaster?

If the plaster was applied to a cured plaster background, a single coat of pva will not have been sufficient to control suction and if pva was dry when applied, may not have helped the situation.

Regarding the grit or no grit argument.....I ain't used grits for ages, after the fad went away still got 2 tubs in the garage! Just ain't got the time to use it and if you prep surfaces correctly and/or use pva correctly there's really no need unless you wanna drag a job out!

That said mind you and having read your post where the phots are, plastering is not an exact science so it may be a genuine 'unfortunate' situtaion. Give the guy who did it the opportunity to put it right....., there'll be too many people on Bloggs like the one you used to post your phots who think they know everything....., who are more than happy to offer armchair advice when they've finished their shift at the local call centre!
 
F**k grit pva all the way but hy when you do need a key hand full or two of kiln dried sand in strong pva never hurt me (happy days)
 
Ive gone back to pva again recently and its a great product on high and low suction backgrounds, knauf and bg high suction primers are brilliant but a bit pricey.
 
I let pva go right off and then go straight over it... painted or not... it works for me :)

I use to use a lot of WBA but then I was doing a shed load more work :D
 
How many use it the same day? A lot of my jobs are one day jobs so I rarely get to use it for fear of it failing
 
I use it on one day jobs.... but call down the afternoon before to sheet up and grit it... might take an hour or so but save you an hr the next day
 
Thats a good price Windy.......even cheaper at R&J Builders hardware if you buy 4 or more tubs,£17.88 last time I looked.
 
Looks like the PVA dried completely before applying or the first coat set to quick. Maybe u had the heat blasting too.

Give him a chance to put it right before u hit him with your homework. Could be an honest mistake
 
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