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New build, completed Sept05, internal and external cavity walls with Celcon blocks on concrete blocks below dpc - metre deep footings on sand/greensand site.

Have noticed vertical cracks externally and corresponding internally - ie cracked blocks inside and outside beneath quite large pvc casement windows. However, no diagonal cracking at the corners of windows. External rendered - internal plastered. The cracks are hairline and been refilled twice now but keep re-appearing

No cracks beneath these below DPC where Celcon meets the concrete blocked footings.

Keep being told "Just shrinkage" - but inside and outside, same locations - each about 2 metres from same corner - 3 years down the line?

Any advice very welcome, thanks.

This is quite common with these type of blocks. The cracks stop at the DPC.

[quote="stuart C"]This is quite common with these type of blocks. The cracks stop at the DPC.[/quote]

Thanks for that reassurance - any way to stop it though,; have used acryllic sealant, polyfilla, etc. still keep reappearing. :(

with celcon blocks the mortar used must be weaker than usual,so I assume the mortar was quite strong causing to much expansion .
but nothing major to worry about.

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