Raft Foundation and a New Patio

5 Nov 2008
Reaction score
United Kingdom
Hi All

I live in a house that's built on a raft foundation so I have a 3ft concrete border around my house.

I want to do a rear patio at the back but the first 2 patio slabs will be on the raft and the remaining 4m will be on the soil.

As the raft is theoretically always moving separately from the other 4m laid on a lean mix base on top of the soil. What do I need to do to make an allowance for this so that I don't get cracking between the 3ft raft and the slabs laid on the soil?
Sponsored Links
There is not a lot you can do about the differential movement other than going overboard on the remaining part of the patio, i.e. laying concrete under this bit.

Bridging the join with a full slab may help. The other option would be to have a deliberate join at this point though this would likely cause problems in colder wetter weather. A gravelled join would work but I'm not a fan of gravel or any aggregate borders for that matter.

Are you on clay or unstable ground?

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links