extension over garage.

23 Mar 2005
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United Kingdom
Hi I currently own a semi detached house with attached garage. The garage is full length of the house and currently converted into a bedroom and half of the rear kitchen. The garage has a tiled roof. There is a crawl space under my house about 4 foot. Would you say the foundations are stable for the extension on top of the garage already? Would I still need to dig a test hole outside the house to please building control.
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I'd have to guess at around 1960s and has a cavity wall. Breeze block and brick.
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Even though you could probably see its deep enough from inside. Under stairs there's a hatch to crawl space.. still need to dig outside? Any paticularly point to dig?
You need to establish the thickness of the foundation and how far it projects beyond the face of the wall - which will determine its suitability to take an extra storey. Just inside will do. And once you know that you will have found the depth.
Thanks Freddie I'm with you now. It's the concrete foundation depth I need to know and width. What specs am I looking for to have the go ahead
You will prolly have to set the front elevation back, meaning a pair of steels and foundation reinforcement. this would be one good place for a test hole.
How do you propose building cavity walls above the garage? Are they cavity at present?

If not, this could mean more steel and more test holes.
Will get the spade out at weekend.....dig a test hole. NOSEALL why do you say I probably have to set the front elevation back a bit? The converted garage is already a cavity wall build. Here's hoping whoever had the house before had the hindsight to put the extra foundations in for future extension.
So the test hole I'm digging needs to expose the concrete strip foundation, what depth and width am I hoping for exactly?
Cheers for your time guys
Probably have to set the front wall back to keep the extension subservient to the existing house, very typical of side extensions. A foundation sticking out say 4-6" beyond the face of the wall and say 5-6" deep would be a good start. But your engineer will be able to prove it will work once he knows the size or if not some additional founds will be required and you will need an engineer. Set back say 1-2m.

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