Cracking plaster

[marct]

Hi,

Could anyone tell me why the last time I plastered I got some areas of cracking? I gave the wall a couple of 50:50 coats of PVA first, was this too weak a mix to stop the plaster going off too quickly, and causing cracking?

Any ideas?

Thanks
Marc

 

[HandyJon]

Sounds like the plaster dried out too quickly. Not the same as going off too quickly. Did you do the plastering in hot weather, or put heaters on in the room to dry it out quickly.

I'm no expert by the way.

 

[TexMex]

If you use the right plaster for the substrate that you are plastering, you shouldn't need the PVA. One reason for cracking, is if the substrate has movement in it. If your substrate was solid but you have exprerienced cracking you probably either put too much water in your mix in the first place, or used the wrong plaster for the substrate (resulting in the moisture being sucked out too quicky).

In hot weather this can be caused, simply by ambient conditions being too warm and arid. Under these circumstances, giving the substrate a jolly good dousing beforehand may help quite a bit.

 

[marct]

Hi,

The substrate was some form of base coat of plaster over the brick work. The day was a reasonably warm day and no heaters were used. The wall I was plastering on was sound.

Perhaps the plaster mix was a little watery, but not massively.

Thanks
Marc