Repairing Cracks In Thermalite Blocks Price

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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.

If the blocks are used on the external skins then the cracks cannot be covered because they will almost invariably show through the render. Even if the build mortar is the right strength to allow for movement in the blocks, this good work can be undone by applying render that is too strong. A cracked cylinder head or engine block may or may not be bad news depending on the size and location of the crack(s), the value of the casting and what it will take to fix the crack(s) versus what it would cost you to replace the casting. Read what your options are in this Larry Carley feature. Re: How to best repair crack in thermalite wall. Post by wes56 » Thu May 10, 2018 5:15 pm the new photo shows a strange ring shape in the central upper block,what is it.

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 Answers from MyBuilder Bricklayers

Best Answer

is a thermal shock
due to warm and cold water you must use elastic and heat resistant material

Answered 12th Aug 2018

Yes blocks do crack in extreme weather.i would take off render.put mesh on then render.never crack again.even if blockwork cracked.

Repairing Cracks In Thermalite Blocks Prices

Answered 12th Aug 2018

Thermalite Blocks Lowe's

Hack it all off and dot and dab. Thermalite and hardwall dont mix

Answered 13th Aug 2018

Hi.

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?

Repairing Cracks In Thermalite Blocks Price Per Block

If you give me a bit more info. I’d be happy to advise how you should deal with the installer

Repairing Cracks In Thermalite Blocks Price Home Depot

Answered 23rd Aug 2018

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