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- Repairing Cracks In Thermalite Blocks Sizes Blocks
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The internal walls are made up of Thermalite blocks. The main wall is 38 feet long, and two cracks have appeared about 10 feet apart. Both cracks start at the bottom (above the concrete blocks) and go vertically, through the blocks and mortar joins to the roof. They both widen at the top. Width of cracks at the top is approx.
Cracks Yes I understand what you are saying spunky eml, bonding with a mesh bedded in then skim coat. What Iwas saying was to stop the cracks reapearing I didnt kow if I had to remove all the plaster back to the blocks then put plaster board ontop of the blocks and a finishing skim to solve the problem. A #crackedengineblock in a vehicle is not uncommon and certainly does not mean the end of the engine's lifespan. There are various methods of repairing crack. Thermalite blocks are prone to shrinkage. So long as the blocks dont appear on the outside walls this is probably the cause. British Gyprum only recommend boarding on thermalite as opposed to wet plaster because of this. Fill the cracks with a weak mortar and board over using dot and dab.
Bricklaying
We recently had a conservatory built (during very wet and cold weather), last week I noticed a vertical hairline crack running from top to bottom on one wall (wall is 4.5M wide). when the render was tapped it sounded hollow or live. Working with a small screwdriver of part of the crack a 2.5M x 1.5M section of render simply fell off and the whole of this wall sounds live although the other two walls seem sound. It can now be seen that the uniform hairline crack goes the entire height of the wall and there appears to be another starting about a meter further down. I called the company back and they are sending the builder to have a look before they have it re-rendered. I understand that thermalite can shrink and crack as the blocks were saturated when laid. Question is what is the correct procedure now?
There are three hairline cracks running the entire height of the wall from damp-course to the leaded top of the wall, nothing below the damp-course which is concrete block. The cracks are even top to bottom and are less than a millimetre in width. The was just one crack visible before the render came off then two more are revealed but the render over these was not effected.
The wall was built and rendered in February when the weather was both wet and cold but not at frost conditions, the blocks were saturated and since the wall faces South the unusually hot sun this year has pitched on the wall for about ten hours each day.
The builder has said he will do whatever is necessary to remedy it but doesn’t seem too sure as to how to proceed. I have suggested that he angle grinds a half inch gap along the crack and then fill with a expanding joint mastic of some sort – not sure if this is the right way to go, then finally PVA the wall and re-render.
4
4 Answers from MyBuilder Bricklayers
Best Answer
72434is a thermal shock
due to warm and cold water you must use elastic and heat resistant material
Answered 12th Aug 2018
72444Yes blocks do crack in extreme weather.i would take off render.put mesh on then render.never crack again.even if blockwork cracked.
2018-08-12T19:30:02+01:00Answered 12th Aug 2018
72495Hack it all off and dot and dab. Thermalite and hardwall dont mix
2018-08-13T21:50:02+01:00Answered 13th Aug 2018
72770Hi.
Repairing Cracks In Thermalite Blocks Sizes Blocks
If the render appeared ‘live’ before falling off, it is the bond between block and render that is at fault. Possibly caused by a combination of excessively wet block (although rendering wet blocks can be ok) and an overly weak mix. If it was cold during the build and the render was affected you frost, this could also account for problems.
I would take issue with ‘.....blocks do crack in extreme weather....’ speak to any block manufacturer for clarification of this.
Occasionally a block WALL may crack in extremely dry conditions if it’s foundation bears on highly plastic soil, and this shrinks due to reduced moisture content (dry summers/demand from proximal vegetation). I have never known a single BLOCK to crack -50<T<50 degrees C.
I would advise against simply meshing and rendering if there is a prob with the blockwork. You do not state wether the crack is in the block as well as the render. If the blocks are cracked, there could be an issue with the footing. Crack wider at the top?
If you give me a bit more info. I’d be happy to advise how you should deal with the installer
2018-08-23T19:00:02+01:00Answered 23rd Aug 2018
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Repairing Cracks In Thermalite Blocks Sizes Concrete
I've recently built a 2 storey extension and noticed vertical cracks appearing on the internal thermalite/celcon walls. The widest is probably only 1mm wide tapering off to nothing. There's also a number of hairline cracks at various places around the build, all of which are internal. Should I be worried? Do I need to do anything before I board it out? Thanks...Chris
22 Answers from MyBuilder Extension Builders
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24896Repairing Cracks In Thermalite Blocks Sizes At Home Depot
Thermalite blocks are prone to shrinkage. so long as the blocks dont appear on the outside walls this is probably the cause. British Gyprum only recommend boarding on thermalite as opposed to wet plaster because of this. Fill the cracks with a weak mortar and board over using dot and dab.
2013-06-01T16:05:02+01:00Thermalite Lightweight Building Blocks
Answered 1st Jun 2013
24890thermalite blocks always crack. I personally wont use them, I use toplite. If you are dot and dab probably be ok
2013-06-01T16:05:02+01:00Thermalite Blocks Price
Answered 1st Jun 2013
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