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We are building a singl storey extension which extends 2m out from the back of the house and 5m accross. The footing are 700ml wide & 1m deep.

We are now hoping to mix the concrete ourselves and fill. The only problem is we are not sure how much ballast to cement to use. Is it 6:1? That is what we have been advised but donot want buildings inspectors to make us rip it all out if its wrong.

We have had buildings inspectors out tio check the foundations but the application to building control is still pending.

The ground around here is pretty clay-y not sure exactly what % though.

Thanks :lol:

RachelC9

I'd suggest that a 1:6 mix is a little light and would prefere to specify 1:4. This should be gauged using a bucket of cement to 4 buckets of ballast. Do not gauge with a shovel as you'll end up getting it nearer to 1:8.

Hope this helps

LCL