Wall cracks

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Neilly

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Wall cracks
Wall cracks
Hi Lads, I'm not a plasterer (floor screeder) but I've followed this site for a while. This isn't really an issue with plastering but would like to hear the opinions of people in the trade. I live in Donegal in Ireland and there's a major problem with houses in the area, the concrete blocks used in the cavity wall construction contain a mineral called Mica muscovite. This is present in the aggregate used in the blocks and the fines (Quarry dust), this makes the blocks like a sponge soaking up water and swelling up causing cracks. The inside leaf of the cavity isn't affected but the outside leaf under constant attack from the lovely Irish weather is deteriorating, luckily the last 5 or 6 winters have been reasonably mild and freeze/thaw hasn't been an issue. At the minute a group has been set up trying to get the government to put a redress scheme in place, some homeowners are chasing the manufacturer and others are going down the road of paying out of their own pocket. The common repair is to take down and rebuild the outer leaf. I have got to the stage with my own house where I can't leave it much longer, plenty of people offering advise but most of them are trying to save money which might not be the best option. A few houses have been re-plastered with Sto using a fibre mesh to wrap the house, I think my own house is too far gone for this option. I'm thinking of building a third layer rather than taking down the outer layer as I would be concerned that too much upheaval could weaken the inner leaf. What I'm asking you guys is what products would you recommend for the finished wall? I've added a couple of photos to show the extent of the problem.
Wall cracks
 

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1st. could you not claim on the property insurance ?

if you build a third skin you would need a footing for the skin to sit on.
i would remove the out side skin and rebuild. the weight of the roof is sitting on the inner skin. the outer skin is not structural

i would not be happy putting a external wall insulation on those blocks. to much movement it will cause problems later.
 
If you strapped all the external angles with plenty of straps then fully meshed the building with EML and gave it a sand and cement coat. Then maybe go over the top of that with another system ? Maybe EWI but I recon a few firms wouldn't guarantee it won't crack but might be an option.
 
If you have issue with external
& money allows just
Take it down re build
Pissing around with existing would prove to be a headache & no guarantees ect

Internals would need appropriate propping
To take load off floors roof ect
Good luck getting it sorted
 
That render has failed on every possible level. Whatever you do it needs to come off. Third layer will be like rendering over floating islands. The pictures are very impressive , but I am sure you a te not aware what the real damage is. Hack ff the render and let it dry before you do anything .
 
Hack it off!! Acess damage Insulation board and render. Or take block work down in sections and rebuild with medium weight concrete block or go maybe go down the route of sealing old block work with a 2 part epoxy waterproofing paint (good quality 1 delta membranes do a very good 1) and then insulate and render
 
Have you got the space under soffits and on gable to build a timber frame in front and then use render carrier board?
Saves taking it down.
@imago would be a good one for this!
There is way to much movement to go over existing with another render no matter the prep you do.



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Fcuk me!!! As soon as I seen it, I knew tgeat house was on this island! I've heard about your situation but never seen pics as bad as yours. IMO, there's only one 'right' way to deal with this and that is to take all them block down and redo it. If you go sticking EWI over it, yes it might do, but one day your EWI will crack to and that's an awful amount of money wasted. Take it down, redo it and you'll be able to sleep well at night once its fixed. O and don't go buying them blocks of the same cowboys, find a decent block supplier and do it right.

P.s, going by your 2nd pic, make sure you get a plasterer who knows how to mark out right size coins when rendering your walls again. They look awful to me, to thin and narrow for my liking.
 
Jgreenplastering said:
@imago would be a good one for this!
There is way to much movement to go over existing with another render no matter the prep you do.
Click to expand...

There's not a lot I can add to be honest, as @hail hail and others have said (including the OP) there is only one way to sort it properly for the long term. Have the outer leaf down and start again.

Anything else will be a waste of time and probably cause more problems. If you cover it with render/EWI/mesh etc the blocks will still blow and move and then the outer coating will be screwed and you're back to square one. If you build another skin outside the one that's there now you'll have a massive amount of interstitial condensation developing either side of the middle leaf. The blocks in the middle leaf will continue to blow, but now they'll push agaist the inner and outer leaves through the ties and you'll basically end up pulling the entire walls down to sort it.

You could replace the outer leaf with insulated timber panels, but that'll prbably work out more expensive.

It's a sh1t position to be in, but there's really only one way out of it.
 
OP, I watched a documentary on RTE about this few weeks ago and was shocked to say the least! You can lift a block and break it with your own hands and it crumbles like it's nothing. Can't believe they built houses with these blocks. Only solution for this is to remove all block and redo. In some cases, knock the house down.

It's been the quarry's fault using to much of that stuff in it that absorbs moisture from its surroundings and makes the block weak. Not only have they built houses with it, there's miles and miles of roads been built using same material but they're trying to keep that swept under the carpet.
 
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