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Groundwork & Foundations

Building Block Annexe on existing Concrete slab?

Anonymous user 03/03/2024 - 3.43 PM

Hello We are in the early planning stages for a double garage with en-suite annex above. Currently on the site is a 6 year old double garage (oak frame) with a 165mm concrete base. The new building will be the same depth but a metre wider. (9m x 6m) Will building regs allow us to build on the existing concrete slab provided it can be extended and tied into the existing slab? The new building will be block and rendered. It's a solid existing slab of 165mm which has been in around 6 years. We believe the previous owner had intended to build a brick built garage but went for a timber/oak frame instead as they'd spent too much money on the main house! Any thoughts appreciated. Many thanks Mat

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3 Answers

Anonymous user

Building regs might allow you to use the slab as a floor in the new Develpoment, however there will need to be new foundations, chances are the slab is actually a raft (meaning there is no deep foundations) if it’s detached? It’s normal for a detached garage to be built on a concrete slab with a deeper edge than the middle, so although it’s 165mm at the edge it may only be 100mm in the middle! It’s also unlikely there is any insulation under the garage floor, again building control won’t like this
Answered29 September 2022
12

Moore Construction

Rating: 5 out of 5
Coalville
Hi that’s not ideal really as it may crack or sink and be unsafe with all the weight on it to do a proper job it would need 450mm deep foundations poured at 300mm concrete and two course of engineering bricks to build the Blockwork up off reduces the chance of damp and perished bricks / blocks in the ground 👍
Answered26 July 2022
0

Anonymous user

Your have to get a structure engineer to have a look into the above anix a to whether the structure is strong enough for the anix as for the extended area 165 is sufficient for the part that you wish to extend hope all goes well and best wishes
Answered31 July 2022
0