Cracks in plaster and breeze blocks Ask your questions and find answers on many subjects relating to plastering and dry lining

[hendon1]

I've bought a 1985 built house that has vertical cracks in the corners of most rooms, at the junction where each wall meets another, the cracks running from the top to the bottom. The cracks are anything up to 5mm. The surveyor put this down to "differential movement" where different materials move against each other at different rates. Apparentely this is not subsidence as there are no cracks diagonally from windows and the outside walls are not cracked.

My concern is that I have chipped off the plaster and can see that in some cases the breeze blocks themselves have fractured.

I have brought in a local builder who told me that this is nothing to worry and is initial settlement/shrinkage and all that needs doing is to put some wire mesh (known as EML - Expanded Metal Lath) on the cracks with sand and cement, covered over with a skim coat of plaster.

Any ideas?

[DUDE DIY]

Hi there, all sounds quite normal. If house was built in 1985 it will be well settled now. House settlement can take a number of years so if there was any major structural problems then you would know by now. Even newly plastered walls can show shrinkage cracks after short periods. If your still concerned then get a few builders in to look at the problem, if they all say similar things you know its nothing serious. Hope this helps. Cheers

[hendon1]

Thank you Mr Dude.

I've since got in a second builder over the weekend who is all doom and gloom - he said that the breeze block cracking worried him and that if it was just shrinkage only the plaster would have cracked.

The surveyor stands by his word and said that breeze blocks aren't that strong and are prone to cracking. Have you heard of breeze blocks themselves cracking?

Thanks

[DUDE DIY]

Hi, I have heard of breeze blocks cracking before, so yes. If you can imagine all the houses in England im very sure people live quite happily in places where there unaware of breeze blocks are cracked behind there internal walls. If its localised to a small area, as it is in your situation then I wouldnt be overly concerned. To some extent the second builder you had out is right. Shrinkage on plaster is different to the breeze blocks cracking. Have you checked the outside of the wall?...do the external bricks bow outwards or seem to be effected?. Only then would I have casue for concern. The make up of a breeze block isnt particullary a strong construction, there quite easy to break so there prone to crack under some pressure. My advice would be to get a few more builders out. Dont be paniced into major work by builders horror stories. Hope this helps.

[hendon1]

Thanks for that. I've checked the outside walls and they look completely true and straight. What gives me comfort is that the three rooms in the house that have been decorated have no cracks, so filliing and making good seems to have worked (believe it or not most rooms in this 1985 house that I've just bought appear to have never been decorated)

Interesting that you should mention breeze blocks not being strong - the original builder that looked at my house told me that the blocks are not concrete breeze blocks and are made of a brittle and weak material.

I'll have the cracks made good with sand and cement and EML and decorate and keep my fingers crossed.

Thanks again.

[DUDE DIY]

Cool... im sure all will be fine. Good luck dude. Merry christmas

[speedrush]

Hi!
I am having a similar problem, only discovered yesterday. I wonder if after all these years you could tell me if the problem has been resolved with EML or have you any more info on this?
Thanks
Christa

[welsh brickie]

Your block is thermalite by the sound of it,The reason for cracking is the mortar being made to strong,the motar will harden consistanly over the years and expand,this leads to the cracking.