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Plaster falling off newly plastered walls

My son has recently had his walls skimmed by a plasterer. Almost instantly the plaster has started to fall of the walls. The new plaster is not attached to the wall in large ares. If you tap the areas you can hear that it is hollow. I understand the correct term is the plaster has blown. He has repaired it a few times. each time it has fallen off again. He finally got it to stick by using a shim.
The plaster is still falling off. As soon as you go over it with a paint roller it just takes off the plaster. The plasterer is saying that it must be due to something being applied to the walls by the previous owners, because he has never come across this in all his years off plastering. Does this sound reasonable? How can the rectify the problem?
They paid £1000 for this job, and are thoroughly disheartened. They have a new baby due in about a monthe, and need the house sorting before then.
Many thanks

Many, many thanks for all you very helpful answers

34 Answers from MyBuilder Plasterers

Best Answer

Hello Sandra,

Basically it has to come off I'm afraid by what you have explained the PVA sealant coat applied prior to skimming the walls was to weak or it was left to dry out before applying the plaster, it has to be mixed to the correct ratio and be a quality PVA, not your local DIY store watered down brand,, it has to be tacky just prior to plastering....there is no way around it,, it does have to come off, stop wasting paint, get the said plasterer to come and rectify what he's done.


Answered 6th Jan 2020

hi i would say that the walls have a lime wash on them or distemper when you pva walls even the day before plaster will come off you have to wash and srape off with hot water then pva


Answered 22nd May 2012

Has the plasterer used a bonding agent (Unibond) ? Could be limewash paint.
To be blunt if he has never seen this before I suspect he has little experience
of older buildings which I have to assume is what yours is .
Little recourse I am afraid, but I would like to think plasterer would so his best to redress situation if he values his reputation.
We all make misjudgements from to time, but if this is happening all over then it must be removed and redone with lessons learnt about background surfaces.
Perhaps you could agree a half and half cost liability. Either that or get someone else and start again. Legal road not worth going down as expensive and will not resolve anything!
Sorry no magic wand,


Answered 21st May 2012

A lot of good replies covering everything except the use of febond bluegrit, plasterers pregrit, or the more expensive thistle bondit. These can be painted on glossy surfaces and have a fine aggregate in to give a key. As long as the surface is sound. I always use this stuff on overskims or drylining painted walls. Boards and adhesive are a lot heavier than plaster. I'm not saying pva isn't sufficient but I dislike the stuff and prefer to play it safe if possible. I know there's times when it's not convenient as the grits need plenty of time to dry. The price of 10litres of pregrit is around £13 so worth it in my eyes if possible.


Answered 17th Jul 2014

the walls should have been unibonded prior to skimming and any blown areas rectified beforehand ,sounds like he has just skimmed straight on thus the plaster has dried tpp quick and not adhered to the existing surface


Answered 21st May 2012

Paul Rowlands answer is most likely right. If it's limewash on the wall, you can put stabilizer over limewash to seal the wall. If it's not limewash/distemper, it could be that the pva is not strong enough. Unibond is a good brand and the skimming is better applied when the Unibond is tacky. Another possible explanation could be the existing plaster was blown creating movement for the the new skim coat.


Answered 27th Sep 2013

there is a very easy way of sorting this out, roller either sbr bond or a waterproof pva (neat) over all problem areas then it can be skimmed as a normal surface as the sbr or pva forms a barrier between skim and original surface and also gives a key to the skim... job done.

if the walls were pva'd originally i doubt this would've happened. i have seen plasterers in the past try to get away with skimming low suction surfaces without pva and it always looses key and comes off...


Answered 21st May 2012

Hi there

Im so sorry to hear your son had a nightmare time with plasterer he hired,
its now best to remove the new plaster and have it re-done i know its not good news or low cost fix, but if there is no bounding adh,(key for new plaster to stick to then theres no way its gonna stay on the walls and ceilings) "no (Unibond) or pva on a re-skimm = loss of key" get a good plasterer in to sort it out.
The best thing i would say is if you hire somone ask to see there CSCS CARD no card no work

"its now time something was done about these so called "TRADESMEN"



Answered 8th Aug 2012

I do a lot of work on older buildings and I come across this a lot on old walls. It takes time to prep the wall in the right manner, which means more cost. Never go for cheapest price, sometimes you'll be put off with cost but I fill upset that the plaster has not rectified the problem. This is because he did not assess the walls and did not treat them with the right bonding agent, I would say the plaster did not take too the walls as prep work was incorrect being lazy. Hope you resolve the prob. b&r plastering


Answered 12th Jan 2014

Most of the answers. Are correct but if you have any doubt about your plasterer please call British gypsum direct they have a customer help line that will answer all your queries but as a rule of thumb British gypsum who is the biggest manufacturers of plaster products don't gaurentee the use of pva any more they only guarantee gypbond bluegrit or any other like product its puts the price up a bit but its far far superior product to help plaster bond but nothing will stick to limewash it would have had to be washed off.


Answered 1st Apr 2016

looks like you have got the answer you need. but just to say it does like who ever did the work never put enough pva on the walls.


Answered 21st Sep 2012

I'm no plasterer but I would use another plasterer if you go into your local b&q and ask if they know anybody local that has a good reputation. Mike braintree


Answered 21st May 2012

Every plasterer knows to unibond a surface prior to plastering so Paul rowlands is right get him to take it back and scrub the lime wash of and reskim it


Answered 12th Apr 2016

Shouldn't the plasterer have recognised these problems before he applied plaster? The plaster has fallen off it doesn't sound like anything wrong with the walls to me, it sounds like the plasterer wasn't doing the job correctly from the start, or the plaster would still be on and ready for painting. Excuses don't put plaster on the walls, GOOD TRADESMEN do.
These people paid a plasterer a substantial sum to plaster their walls and its fell off.


Answered 12th Jun 2012

All suspected problems have been mentioned, probably poor prep work,but your plasterer could also be laying it on to thin if it comes away when Rolling over with paint.p.s you can skim over dry pva as it comes to life when in contact with water.


Answered 29th May 2017

Hi Sandra,
when you plaster a wall the plastering is only as good as the surface you are plastering on. You need to make sure the surface you are plastering is sound/dry and has a good enough key for the plaster to stick! If you are skimming over a glossy surface you need to scratch it up first as unibonding alone is not enough. It sounds to me as though this may be the problem and if that is the case it will all need to be scraped off and re-done.


Answered 21st May 2012

Hi it sounds like the wall hasn't been prepped properly for the skin coat. If in doubt about lime etc then I'd seriously consider going back to brick and starting again. Doesn't sound like it was to do with the pva being a cheap one it shouldn't happen at all as long as any loose areas are removed , bonded up properly and pva applied accordingly then it shouldn't hane happened. Lime or poor prep I.e allowing the wall to dry out too much could be to blame.


Answered 7th May 2016

The walls have not been keyed properly or the pva is not the right consistency scrap the walls and start again!


Answered 29th May 2017

Apply British gyspsum bond it at least 24 hours before appying finish coat.


Answered 18th Aug 2016

He should of used gypsum bile grit unibond


Answered 24th Sep 2016

Hi Sandra,
Sounds like a troublesome wall you got there and yes it seems like it may have lime wash etc as previously commented or it could just be poor preparation on the plasterers behalf, either way, if it was to re-skimmed I'd apply a product called Blue Grit to the affected areas at least 24hrs prior to skimming which will create a guaranteed key for the the fresh plaster to take to eliminating your dilemma of plaster falling off etc.
You can purchase blue grit from diy merchants and paint it on your self which will cut down on the cost of re-skimming which is always a bonus.
Hope this helps.
Many thanks Dan


Answered 2nd Jan 2017

Definitely sounds like it wasn't bonded properly going over plaster i would recommend SBR its alot stronger


Answered 16th Mar 2017

Hi it could be the pva that has been applied prior to the plaster coat may not have been diluted correctly making the mix a weak mix which can affect the plastering setting right causing the new plastering to blow,bubble pop etc also if the paint work was not scraped back and keyed correctly may be a cause to but it sounds as if it hasn't been pva coated before plastering.Alternativly if you have damp problems that have not been rectified prior again this could cause plaster to crack bubble etc every job is different and could be anything but sounds as if trades man just missed a section or sections to be honest thanks Paul pkplastering


Answered 12th Jun 2017

I just read alot of answers on this! Seems like I'm the only one who knows the real answer! Real answer- my old guvnor who trained me was old school and correct! The real way to bond walls is to mix sika uni bond 50/50 ration and give it a coat the Day before with a thick sleeved roller. Let it dry for 24 hours as this seels any hair line cracks and prevents it from peerling of and any distember because it drys it. The next day (after 24 hours) give it another coat of uni bond 50/50 ratio again and wait for it to go tacky! Then apply plaster when it's tacky as it will only bond when it's tacky! No cracks! No blow offs! No come backs! Never had a come back doing it this way in my nearly 20 years experience Listerning to my old guv- words of wisdom fellas there you have it! I shouldn't give away my knowledge to other tradesman on here!


Answered 27th Mar 2018

Bond it should of been applied 24 hrs before the plasterer applied the plaster pva is no good for over skims


Answered 15th Jul 2017

Seems to me that he either mixed up the PVA too watery or he hasn't put none on at all. He should of pva'd all the walls properly before hand then felt the wall to insure it is sticky before applying any plaster. Definitely get him back to rectify the problem.

This is what happens when plasters don't prepare the wall properly. PVA is what is bonding the plaster to the wall without it's just a matter of time before it comes off.


Answered 26th Sep 2017

Either the wall had a weak coating of Pva or its distemper as any plaster should know, call him back to scrub the wall (as mentioned above) strong coat of Pva and Re skim 👍


Answered 11th Jun 2016

It maybe due to the paint finish prior to them being plastered. If the walls where painted in a silk / gloss finish before the fresh plaster then a good bonding agent would have been required. I use febond bluegrit or the more expensive thistle bondit. These can be painted on glossy surfaces and have a fine aggregate in to give a good key. It is always best to play it safe and it gives me piece of mind. This may make the job more expensive but i alwsys give the costume the option to paint this on themselfs


Answered 12th Aug 2016

Needs good coat of pva first.


Answered 26th Aug 2016

Plaster was put on too early not leaving pva soulotion to dry and probly not the right ratio take off all plaster reapply pva leaving it to dry feel when tacky then skim.


Answered 16th Oct 2016

If he's was a decent plasterer he wouldn't leave until it was 100% complete may not be his fault but he should of known how to repair the problem it's the first thing they teach you preparation of background
that's why You paid good money for the work doing


Answered 11th Jan 2017

It will either be a lack of bonding agent like quality PVA, blue grit or SBR, used prior to skimming or an unsuitable background prepared poorly. Old limewash is always a tad flakey with a poor key to the background, old textured paints where someone got a bit to artistic and mixed together whatever they found at the bottom of the cupboard in 1945, and without wiping the contaminated area or scratching it back to a solid base, you won't get the mechanical key you need to stop the plaster coming off like old pastry on to your roller.


Answered 29th Jan 2017

The pva may have been mixed to weak therefore caused the plaster to crack


Answered 2nd Feb 2017

It does sounds like it wasn't bonded properly.


Answered 26th Apr 2017

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