Cracks in new plaster!! Advice?

JayV

I'm hoping someone can give me a little advice....

We got a woodburner installed recently and as part of the job they took out the old fireplace, widened the opening, and replastered part of the chimney breast. When the plasterer was plastering the chimney breast he said that it needed quite a lot of plaster but that he should get away with just putting it on in one think coat. He said that if you put on too much plaster there is a danger it will sag.

Anyway, they finished the job and it seemed fine. We left it for over a week before lighting the woodburner. About 2-3 weeks after the job was finsihed, cracks started to appear in the newly plastered area. They seem to be getting bigger and more numerous.

We have called the people who did the work and they are coming out to have a look at it. I just wanted to know if anyone could tell me what the problem is likely to be as well as the correct fix. I 'd like to have my facts right so that can't try and b*llsh1t me. We haven't paid for anything yet.

Thanks!

jack24

Hi,

We got a woodburner installed recently and were advised to get a metal strip around the fireplace opening to ensure the plaster didnt crack. We went with the strip and the plaster is fine (Buckleys fireplaces BTW)

Jack

JayV

Thanks Jack. We got the metal strip as well. The cracks aren't anywhere near the woodburner. I think the problem is related to the plastering as opposed to being caused by the woodburner..... I think.

Ciara22

Hi,

I'm not entirely sure but I have a theory on why this happens. (Im an engineering student so Im basing it on materials science)

Here comes the technical bit....

When plaster dries, the water molecules come to the surface and evaporate - this is the drying process. I think because the layer of plaster was so thick, the surface dried quicker than the underlying layers. This means that because it is still wet underneath, there are still water molecules trying to travel to the surface to evaporate and dry out. These molcules will cause cracks in the already hardened and dried surface layer.

Basically I think its cos the plaster was laid on too thick, isnt there a max thickness, like 10mm??

game4it70

hi. ciara is correct if the plaster is to thick this can happen.it will look kinda like a spider's web. if so easily fixed with polybond and a quick skimcoat.
i'd say the burner probably speeded the drying process up which didn't help.

GreeBo

FTR, I was repairing some cracks in plaster and also removed a spare socket.
About 1 week later I had to open up the hole again and the deepest plaster (maybe 1-2 inches deep) was still damp.

Elfish

game4it70 wrote:

hi. ciara is correct if the plaster is to thick this can happen.it will look kinda like a spider's web. if so easily fixed with polybond and a quick skimcoat.
i'd say the burner probably speeded the drying process up which didn't help.

Agree with this.

To the original poster, is the wall currently plastered with sand cement or was it skimmed?

Not a big problem to sort, at least the wire mesh was put in - the plasterer isn't a total cowboy.

I'd let him know what has happened, and leave to dry out for a good while yet before getting it fixed up. Know a good reliable plasterer in dublin who would sort it out at reasonble rate if things go wrong with your own plasterer.

John Mason

what everyone said is right but you really should leave your plaster to dry without any heat whatsoever for at least 4 weeks, if it dries too quickly it will crack, but its easy enough to fix with some skimcoat:)

JayV

Thanks for all the advice.

The cracks aren't like spider webs. They're bigger (can nearly get my finger nail into one of them) and there are less of them. They also seem to be getting bigger. I'll post a few pics tomorrow. The plasterer is employed by the company who supplied the woodburner - so they'll have to sort it out. Have a look at the pictures tomorrow and let me know what you think.

Cheers!

JayV

To Elfish: the wall is plastered with skimcoat.

JayV

Attached is a photo (DSCF0435.JPG). The remote is to give it some scale. Will polybond and a skimcoat fix this or is it more serious?

Thanks!

Elfish

Simple to fix.
Quick reskim will sort it out...but do leave it settle completely. Sometimes these fine cracks can be almost impossible to avoid, think your accelerated drying out is large part of the problem.

What I would be more annoyed about, and what WAS under the control of the plasterer is the poor finish on the wall - I can see the finishing trowel marks from here:eek:

Personally, think that reskim would be overkill - if those small cracks bother you that much, by all means get it reskimmed. What about using spackle to touch up after drying has completed - quicker, cheaper, almost as good as full reskim unless you are complete perfectionist?:D

hiscan

that looks to me like its dried out too quickly too much heat too soon