external rendering on breeze block wall??? HELP!

[billiedi]

hi

we have lived in our house for two years and are having to pull the external rendering off cos it was cracked and pushing away from the wall all the way up.

we have just pulled some off to find breeze blocks underneath. this is an external wall of an added extension to our house (done by previous owners). we have all the planning permissions and plans for this extension in our house pack but wanted to know this:-

1. how can we render it properly again and make sure it stays? any advice on rendering on breeze block?
2. is rendering on breeze block actually allowed? why would they even build external extension walls in breeze block? should we approach the council? can we sue/get compensation? surely it wouldnt have been passed by an inspector?

ta
diane

 

[shenks]

Our local BC has no objections to render being applied to solid dense or cellular dense concrete blocks, but it wouldn't be a good idea to have thermolite/celcon/durox blocks rendered because I think they would be subject to very high suction which could affect the end result.

Some of the other guys on these forums would be able to tell you more about this but if the exterior skin isn't thermolite then it could just be bad rendering/preperation that has caused the failure.

 

[billiedi]

thanks for your reply shenks. well, at least i know its not illegal then!


anyone any advice on how to render it properly this time?

 

[shenks]

I'll leave the in depth replies to some of the other trade guys on here, but if you do a search on the forum you should get some good background info about scratch coats, waterproofing agents, etc.

 

[billiedi]

it seems the breeze blocks might be thermolite!

is that bad?

 

[shenks]

Bad? Generally not recommended on thermolite (or so my regular plasterer/rendering bloke tells me). Possibly this is why you have encountered the failure of your rendering.

Over to the guys who actually do these jobs instead of me who just gets somebody else to do them...