Ask a tradesperson

Painting & Decorating

Spider cracks over old patches of plaster?

Hello. We recently bought a 1960s house and started redecorating room #1. We've ended up with what I think are referred to as spider cracks, in multiple spots. I'm pretty sure it's not the paint that's the issue (see below). We're hoping someone help identify a remedy. Here's the info:
* The plaster wall had been patched in multiple spots by the previous owner(s).
* The cracks in the paint appear in multiple spots, but not everywhere (there are large areas of wall completely unaffected)
* I'm pretty sure the cracking is only happening over patches that were plastered by the previous owner, for various reasons: to the naked eye it definitely looks that way, we also tried matching up some pre-painting photos to the current problem areas and it looks to be a good match. I can also see that the same cracking has happened in other rooms in the house where paint has been applied directly on to the plaster walls.
* I re-plastered additional bits of the wall in room #1 myself, and the cracking doesn't appear to be happening over those patches.

These are thick walls, not drywall. The walls in this particular room were papered when we arrived, but underneath they were bare - no paint, just bits that had been plastered.

We stripped off the wallpaper, washed and scraped the walls, then sanded them with an electric sander to smooth them out and try to ensure we got as much of the wallpaper paste off as possible. I guess that would be enough to rule out paste residue as being the issue?

We applied 2 coats of primer/undercoat ( and 1 coat of water based emulsion ( but halted the work when we noticed the cracks.

Here is a picture of the cracking - although it looks to be affecting the most of the wall that's just the cropping of the image there are much larger areas unaffected

2 Answers from MyBuilder Painters & Decorators

Best Answer

Good evening, regarding the spider cracks you have. these are fairly straight forward to repair as long as they are very small cracks if they are a decent size then you will need to use edge of scraper to open the cracks up to a V shape and then use a good quality filler and fill the cracks and when dry sand smooth. If they are small you simply need to sand over the cracks with a medium- or fine-grit sandpaper, feathering the edges. Then use a product called polycell base coat and paint on either over the whole wall or over the effected area feathering out and then once dried and cured ( follow recommended drying times on product) you can then apply 2 x coats of top coat emulsion. I know homebase sells the polycell base coat. I hope this helps you.


Answered 3rd Dec 2014

The cracks are a good indication that before the plaster was applied the patch area was not dampened down with a pva glue, a way round it would be to size the walls and line with good quality lining paper, then apply a mist and 2 full coats..
Hope that helps..
Francis decoration's..


Answered 3rd Dec 2014

Post your job to find high quality tradespeople and get free quotes

Can’t find an answer? Ask a new question

Question Categories