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Wall Crack (Read 1416 times)
TrevorP
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Re: Wall Crack
Reply #10 - Feb 7th, 2017, 8:51pm
 
Yes I think you are right, it has stopped moving, as paper had no cracks at all. Now chased out cracks and most seem to follow the motor line, with a couple with hairline crack through the block.
So am fairly confident now once re-plastered shouldn't get more.
Trev  
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Natedog
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Re: Wall Crack
Reply #9 - Feb 5th, 2017, 10:18pm
 
if it's had paper over it for 9 months, and the paper hasn't cracked too, that would suggest that it has stopped moving
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stuart45
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Re: Wall Crack
Reply #8 - Feb 5th, 2017, 10:34am
 
It's not being a soft block that's the real problem as harder concrete blockwork can also crack.
Blocks when made are initially wet, so as they dry in the wall it shrinks.
Clay bricks are usually the opposite being dry from the kiln so the external walls tend to expand with moisture.
Newly made blocks tend to be wetter and cause more problems, although using something like a 1/2/9 OPC/lime/sand mix can help.
The advantage of an AAC block is that it's lighter, easy to cut and has better thermal qualities although some builders now prefer other types of block.
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TrevorP
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Re: Wall Crack
Reply #7 - Feb 5th, 2017, 9:51am
 
I totally agree about the mortar used, as when I chased out for an additionally socket found it to be as hard as nails.
As the cracks in the blocks are cracks and not gaps will use a mess cover and re-plaster, then maybe a skim coat. We have considered dry lining so if as a last resort will go with it.
Thanks for quick replays and advise.
Cheers
Trev
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woodsmith
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Re: Wall Crack
Reply #6 - Feb 5th, 2017, 8:19am
 
It's not normally the relatively soft blocks that are at fault but the mortar used by the brickie. Thermolite needs a weak mortar but as your cracks are going through the blocks it looks like they used the same mix they would use for bricks, a common mistake unfortunately. I don't think there would be much point trying to rake out the cracks although adding mesh would help. If the problem is not too bad it may be better to paper the entire wall; there are some lining papers available which are designed to hide this sort of problem; B&Q sell one and it does work if the cracks are relatively minor. If the cracks are too bad to paper over, then it would probably be best to dry line the wall with plasterboard.
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TrevorP
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Re: Wall Crack
Reply #5 - Feb 4th, 2017, 10:47am
 
No, have checked and re-checked and there are none. As said this is not the only room with a crack through to and including internal block work, but no external cracking.
That's why I asked the question about thermolite being so very soft, breakable, to me as an ex engineer I would have never used such "weak" blocks that crack so easily, but I know you builders will disagree.
Was also thinking if it would be advisable to open these cracks a bit and try and get some cement in for strength, what do you think?
Trev


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woodsmith
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Re: Wall Crack
Reply #4 - Feb 4th, 2017, 8:28am
 
Are there any cracks in the external walls?
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stuart45
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Re: Wall Crack
Reply #3 - Feb 3rd, 2017, 8:25pm
 
You can do.
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TrevorP
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Re: Wall Crack
Reply #2 - Feb 3rd, 2017, 8:12pm
 
Thank, bit of a relief, should I bridge the crack with a mesh type matl  before re-plastering, after chipping out?
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Re: Wall Crack
Reply #1 - Feb 3rd, 2017, 8:03pm
 
Thermalite and other AAC blocks often suffer from shrinkage cracking as they dry out. It's not really a serious problem.
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TrevorP
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Wall Crack
Feb 3rd, 2017, 12:30pm
 
Just removed wallpaper from room we are decorating, and found quite a few cracks. A couple am quite concerned about, these are fairly large and did not notice with wallpaper on (only been in this house for 9 months)
I have chip plaster away and found the crack is though and in the thermolite internal wall, see pics.
Is this a concern? do I need a structural engClose upCrack to look .at.
The house is a 60s build, and all internals are thermolie block and under and top coat plaster.
What should I do, as I think this is not the only one in the house, do thermolite crumble and fall apart.
There are no external cracks in brickwork.
Any advice much appreciated
Trev
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