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What is the best way to extend a existing old concrete slab
Richard brown 16/09/2025 - 9.12 AM
I need to make an existing concrete slab (old shed base) about 30cms x 3m bigger/wider so that I can lay porcelain tiles on it to make a patio. Any info on how best to do this would be really appreciated. Is it best to use a layer of MOT and then a M20 concrete mix or could I use a 5:1 or 4:1 sharp sand/cement mortar mix on the MOT instead? Either way what depths would you suggest? Many Thanks
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2 Answers
Morgan Groundworks
Rating: 5 out of 5
To add concrete to existing concrete you would need to prep a new sub base digging out for 150mm compacted type 1 mot and a minimum of 4inch concrete depth for the slab as they are laying porcelain on top the fall and levels of the slab need to be extremely precise aswell, as you are adding f new tools there is always a risk of movement during expansion of the new slab which can cause issues with the porcelain so bare that in mind
Answered16 September 2025
2
Mj civil engineering solutions
Rating: 5 out of 5
Hi,prep the ground as per other response,i would recommend an additional bars drill into exsisting slab,like 12mm every 400mm,that would prevent movement.
Good luck with your project
Answered16 September 2025
2