cracking plaster

[stav]

Hi,

I'm looking for some advice. I had a bedroom where the plaster needed to be reskimmed. I got some guys in who skimmed the whole room. I waited two weeks and then painted using the correct paints but now maybe two months later there are cracks appearing in a few places over the walls. What's causing this and what are the ways to recktify it?

Thanks for the help, this is very annoying as the room was looking good until the cracks started.

Thanks
Stav

 

[Richard C]

It could be due to poor adhesion, too thin a skim coat or problems with continued movement of the basic structure itself but if there were cracks in the plaster before & they just plastered over them, they will almost certainly reappear; are they appearing in the same places where there was previous cracking?

I always reinforce/repair cracks before skimming; small surface cracking can usually be repaired with reinforcing tape before skimming but larger cracks that go right through the plaster & base coat (& sometimes right through the bricks/blocks) will need more serious repair work. This can mean a considerable amount of work removing all the plaster & base coat up to 200mm either side of the crack & reinforcing with stainless steel mesh before re-plastering, taping & then skimming.

 

[stav]

Hi Richard,

There were very few cracks in the plaster before, it just needed smartening up. I know the plasterer taped over any cracks that were there but the cracks that are appearing are not in the same places.

There are several small cracks around the walls now and one long one that just seems to go on extending. It's been around two corners and keeps going.

any ideas?

 

[roughcaster]

What are your walls constructed of, eg. lathe and plaster, block, brick, plasterboard?.... Tap around and along the cracks to hear if they sound hollow underneath.....could be as Rich'd says, "poor adhesion"...... Any chance of a picture so we can see the actual cracks?

Roughcaster.

 

[stav]

Here are some photos - hope you can see from them ok. the walls are brick behind and then there was plaster on top. My skim coat was put on top of that.

If it's poor adhesion what does that mean needs to be done. If i tap the wall around the crack it sounds solid.

 

[stav]

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[roughcaster]

I wouldn't even like to guess what would cause cracks like that to appear just like that. They seem to be structural, as if following the joint in the brick/block wall, rather than just "cracks in the plaster". The vertical one seems as if it is a corner beading coming off ?... I honestly don't know.

Roughcaster.

 

[Richard C]

As Rough says, it's difficult to say without seeing it in the flesh but by the look of it, I would say you have on-going structural movement problems there. If that’s the case there would surely have been previous evidence which begs the question, why didn’t your plasterer advise you as such? Unless you’re in an area that suffered a mini earth quake recently! As for easy repairs, it doesn’t look that promising to me; it’s probably not entirely their fault (if at all) but, personally, I would call them back in & see what they say!

 

[roy c]

I would say that they are "movement" cracks, Why don't you hack around the horizontal one about 2 inches above and below (the one where it looks like a bit of plaster is missing) I think that you will find that the backing coat and top coat may have "blown" off the brick work. I dont think the plasterer taped over these cracks that have appeared!!!

 

[stav]

thanks for the replys. I don't believe there were any cracks in the original plaster, definately not like the one that's opened up. I stripped all the walls of paper and the plaster behind where the crack was solid.

We've just moved into the house and the survey did not pick up anything about a structural fault with the room, which is an extension on the back of the house.

I have the plasterer coming to have a look next Thursday so I was hoping to have a bit of knowledge about what the problem is. Someone suggested they did not use enough or any PVA?

 

[jbonding]

i honestly think you can forget blaming the plasterer on this one, like what most people have said this looks structural, are there any signs of cracking on the outside? Has anyone crashed into your house in a car or something similar?

 

[Richard C]

i honestly think you can forget blaming the plasterer on this one, like what most people have said this looks structural, are there any signs of cracking on the outside? Has anyone crashed into your house in a car or something similar?

That is one hell of a crack to appear out of nowhere & no amount of PVA would have stopped it. Are you (or your neighbour) doing any other building or ground works nearby? & I was being serious about that quake; there have been a few in the UK this year!