Plaster bubbles / lumps

lnos1

Hi,

I would really appreciate advice in this stressful time.
Our house had internal plastering completed last November and we finally moved into our house 2 weeks ago. When we turn on a lamp, all the walls have lumps and are bubbling. Some of the lumps are hollow. This is on nearly all the walls throughout the house.
The house is more or less finished, furniture, painting etc. I have been told that the plaster was slow to set and because of that, it was under-trowelled.
The builder wants to apply Gyproc Pro Mix to all the walls and sand them down and then re-paint. Is this ok? The builder said they would chisel out the hollow lumps and fill them. I don't know anyone who has used this product. I have been advised to take down all the old plaster and apply fresh plaster. This is a stressful thought as I have a baby in the house, but at the same time, I would like it done right and I am willing to put up with the hassle for another month.
What would be the best thing I should do? The builder seems genuinely committed to fix the problem. I was thinking of getting the plaster replaced where the walls are desperately bad, and sand the walls that are not as bad.

Any advice would be appreciated.

The other fella

lnos1 wrote: »

Hi,

I would really appreciate advice in this stressful time.
Our house had internal plastering completed last November and we finally moved into our house 2 weeks ago. When we turn on a lamp, all the walls have lumps and are bubbling. Some of the lumps are hollow. This is on nearly all the walls throughout the house.
The house is more or less finished, furniture, painting etc. I have been told that the plaster was slow to set and because of that, it was under-trowelled.
The builder wants to apply Gyproc Pro Mix to all the walls and sand them down and then re-paint. Is this ok? The builder said they would chisel out the hollow lumps and fill them. I don't know anyone who has used this product. I have been advised to take down all the old plaster and apply fresh plaster. This is a stressful thought as I have a baby in the house, but at the same time, I would like it done right and I am willing to put up with the hassle for another month.
What would be the best thing I should do? The builder seems genuinely committed to fix the problem. I was thinking of getting the plaster replaced where the walls are desperately bad, and sand the walls that are not as bad.

Any advice would be appreciated.

Who told you that? I very much doubt thats the reason.Is it plasterboard or sand and cement walls its happening on?

lnos1

All the walls are block walls so sand and cement used.

The other fella

Sounds like it could be an adhesion problem to me but i cant tell for sure without seeing it.
Maybe if you know of any plasterer that isnt linked to the job or the builder, you could get him in just to see what he has to say.

If any skimcoat has fallen off and you have access to the basecoat, check to see if you can scratch it with a key.Its more than likely a problem with the sand and cement.

lnos1

Thanks.
I rang a different plaster and he said it sounds like under-trowelling. But some of the lumps def are separating.
Would you recommend knocking off the plaster and re-plastering?

The other fella

lnos1 wrote: »

Thanks.
I rang a different plaster and he said it sounds like under-trowelling. But some of the lumps def are separating.
Would you recommend knocking off the plaster and re-plastering?

I dont know how bad it is, but if its only certain parts maybe the best thing to do would be let the builder chisel them out and patch it up, would save you a lot of hassle.

But if its real bad it would be a shame to have freshly built walls full of patchs and getting it re done might be the best thing.Like i say though, getting a professional second opinion by bringing someone in to see it would be your safest option

PaleRider

Hi
Sorry to hear about the hassle your getting. It may be that the walls were Skin-coated before the sand & cement set/dry. About three days is necessary. Skim Coat has a predetermined setting time, It is more likely to be over troweled.

If the plaster is coming of in lumps - this may explain that. If this was happening you would find sand & cement attached to the lumps of skim-coat. This method of work would not allow the plaster to be troweled correctly.

However plasterers would notice this and should have corrected their methods. I,m shocked that the builder would not have noticed this. Plastering has a drying/setting pattern which would alert the builder to something wrong.

Why was this not picked up before painting. What are the ceilings like. You can re-plaster over the painted walls. Keying the wall is very necessary & uni-bonding. If the walls are bad then re-skim coat. The method you describe for repairing the walls - works best with walls not painted. Have you any photos.

Power sanding may be necessary. The projecting lumps are difficult to sand. Start with one wall first - and see what works best.

whupdedo

Yes it sounds like under trowelling, if the sand and cement wasn't fully cured it wouldn't adhere correctly and that combined with under trowelling leaves the texture you describe, you have a couple of options

You can try sanding, if it works it might be the fastest way around it, but very dusty

Key the wall with a product like thistle bondit, sand wall first and apply and skim over

You could use a product like gyproc multi finish and sand back after application

Whatever road you go down, I would strongly recommend you don't let the plasterer that did the job initially back inside the doors of your house, get someone else that comes with strong recommendations

lnos1

Thanks for all the advice. I met with Gypsum representatives and the builder today. They told me that the plaster was most likely slow to set and it was under trowelled. The plasterer working for the builder has been with him 30 years and had a good reputation. The builder told me that the plasterer rang Gypsum to say that it was slow to cure at the time and that Gypsum told him it was fine and to trowel away.
Gypsum have told me this evening that my best option is to use their Gyproc filler. They say the lumps are from water gathering under the skim coat. They admitted that they have never seen it as bad as on my walls. The whole walls are lumpy. Some of the lumps are hollow and they said the builder would chisel those holes out and Gyproc them. It is hard to see them in daylight unless you turn on a lamp or you look at the wall eye level. The builder showed me the worst bit of plaster where he gave it a tap with the hammer and about 1 foot diameter of plaster fell off. A lot of the plaster does seem firm but I am not sure.
I have been told that Gyproc is an inferior product to skim coat and that they are using the cheapest and easiest way out.
Is this true?

lnos1

Does anyone know how to get new skim onto hardcoat when the current skim is falling away? There seems to be dust on the hardcoat when the skim falls off and the bond may be affected if skimmed directly onto the hardcoat?

D_D

lnos1 wrote: »

Does anyone know how to get new skim onto hardcoat when the current skim is falling away? There seems to be dust on the hardcoat when the skim falls off and the bond may be affected if skimmed directly onto the hardcoat?

You can remove the skim coat below and then apply a product called Thistle Bond. it is effectively a glue with sand mixed in to give a key for the new plaster to adhere to.