Plasterer has plastered over lime render!

[AH1212]

Hi all,

I recently had my entire house skimmed. In the six months following this. I had a number of hairline cracks show on the walls and, according to what I understand, this is normal as the house moves so i simply filled the cracks, sanded down and proceeded to mist coat. However, these cracks have since got worse and more are showing and some are actually flexing (coming away from the wall) with large portions of the wall (lime render) coming away at some points (see image below). I called the plasterer and he said it had blown and I paid him to bond and reskim the issues. However, these are occurring everywhere now. I have spoke to a few plasterers and have said that the plasterer should have sealed this prior to skimming? Should he have checked it was lime render prior to commencing work or was that down to me? I also spoke to the lime Cornish company after testing a small sample of the render with vinegar to check it was lime and they also said he should not have used gypsum multi finish over lime render.

Some have said to remove old lime render back to the brick which I know is a lime mortar. If this is the case (which would essentially mean I have wasted days and thousands of pounds), I am thinking of have the place boarded out (dot and dab). However, I do not want any more issues. I have been reading up on how to ensure a good seal between the wall, the board adhesive and the board. Some say pva, some say sbr and some have recommended different products. I am not carrying this out myself but I certainly want to understand the correct process to avoid another situation like now. If there are any reputable plasterers in Exeter, Devon, who are interested, please give me a shout.

Disappointed is not the word. I have attached some images below (the two smaller ones are where the skim come away from the ceiling after a light sand).

 

[StephenStephen]

If I was doing it myself, I'd use lime plaster - have a look at Mike Wye's videos. If I was paying someone to do it, I'd strip it back myself and check out Jack Henderson to lime plaster - he wouldn't be cheap, or likely to be able to do it soon, but I'd expect him to do a good job.
My amateur experience is that lime is easier than gypsum because it goes off more slowly, but it's more expensive to pay someone to use lime - because it goes off more slowly.

 

[ree]

OP,
I'm sorry to hear about your expensive troubles.
If the background is lime render on an internal wall then using the gypsum multi finish would be OK. Otherwise use Remedial finishes such as Limelite etc.
But if its an outside wall, or a wall that has previously received remedial treatment, then no gypsum should be used.
From the pics it seems the finish is delaminating/shelling from the background because of poor prep ie. the suction wasn't taken up before the finish was applied.
Sometimes its best to use a couple of coats of 50:50 Pva or SBR etc. before the skim or even before rendering the background brickwork.

What you should do next I dont know because I'm not there?
But, for a number of reasons, I would stay away from lime putty plaster.
Is the ceiling plaster laths or plaster board?
Lime mortar in the brickwork is irrelevant.

 

[cdbe]

I'd start by removing everything that's blown and see what's left. You can tell by knocking - if blown it will sound hollow. Even if extensive it could be salvaged.

 

[AH1212]

OP,
I'm sorry to hear about your expensive troubles.
If the background is lime render on an internal wall then using the gypsum multi finish would be OK. Otherwise use Remedial finishes such as Limelite etc.
But if its an outside wall, or a wall that has previously received remedial treatment, then no gypsum should be used.
From the pics it seems the finish is delaminating/shelling from the background because of poor prep ie. the suction wasn't taken up before the finish was applied.
Sometimes its best to use a couple of coats of 50:50 Pva or SBR etc. before the skim or even before rendering the background brickwork.

What you should do next I dont know because I'm not there?
But, for a number of reasons, I would stay away from lime putty plaster.
Is the ceiling plaster laths or plaster board?
Lime mortar in the brickwork is irrelevant.

Hi, thank you for the reply. He definitely used and applied PVA. How much he applied and whether he used two coats I am unsure.

I am not really sure where to turn with this really but it looks like I am gonna have to pay to have this redone one way or the other as I cannot 100 percent prove he is at fault and really do not want the hassle of going through the courts (if I had concrete proof then I might).

As for the ‘shelling’ that would explain some of it but really it is all over the place so I am unsure. I’ve had another plasterer take a look and he believes it is limewash and it could be that making it flake and weaken. He recommended removing the hollow sounding render and bonding and skimming this but given quite a bit of it is hollow (probably 50%) he suggested either reboarding and skimming or knocking all the render away and skimming.

I am not denying some of the render behind is ****e, but surely a plasterer would check what they are skimming to before skimming? Or is that not accurate?

 

[AH1212]

I'd start by removing everything that's blown and see what's left. You can tell by knocking - if blown it will sound hollow. Even if extensive it could be salvaged.

Hi, yes that is basically what another plasterer told me to do. Not sure if this helps but where all the cracks have formed and that weird shelling/flaking plaster has occurred, it is hollow.

I think I know the answer to be honest with you and I guess I am just clutching at straws and someone has a magic answer to remedy this without the cost and upheaval yet again as it means basically ripping out a new bathroom as well.

 

[AH1212]

Just a quick update, I have conducted further vinegar test on not only the render but also the brick mortar and it violently fizzed to indicate lime based.

Oddly the external walls are not too bad. Internal walls were affected more with the gypsum plaster. As noted above, the plasterer that skimmed my property six months ago is not admitting fault. The question now really is if o get another plasterer in, what do o have to ensure he does as they will likely bond over it with gypsum and then skim.

 

[ree]

OP,
Your replies are getting a little confusing.
How about trying this: using any steel trowel or a taping knife, slide the blade under the skim and prise off the skim finish only not the background render.
You will be purposely shelling the finish.
Try it on one wall only, & see how you get on?