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Hi, can anyone advise?

I will be putting in a building notice to convert my integral garage in my bungalow in late spring/early summer and i'm trying to cost it up. I don't have the resources to employ a builder (wish I had) so I have to do it myself, (planners say it's a permitted construction). The garage is part of the main bungalow and there's a lintel above the garage doors. I will be taking out the doors/frame and building up a cavity wall to take a new double glazed window. The head will but up to the rendered lintel.

Can anyone tell me what size footings I will need? In conversation with friends they think I will need to dig a 1metre deep by 450mm wide trench for the footings, does this sound correct? it seems a lot of footings to support a few blocks below the window. If correct how thick does the concrete footings have to be (surely not 1 metre)?

Thanks

russellfl,
Do a trial dig to see how deep and what size your existing foundations are. If the boot is big enough you could alway fit a PCC lintol to carry the brickwork under the window.
end

Hi

If your luckly the existing footing may already go right through.

Do a trial pit if not the best solution is to lintel across using concrete lintels as already quoted.

Bye

Thanks for the response guys, i will do a test dig to see whats there. the garage floor is a concrete slab and is about 100mm below the main house floor so if there's no footings i will also have to break up the concrete to put in the new footings, so as per my original question, how deep and wide would the new footings have to be?. I'm not sure what you mean by putting in a lintel, where would I fit it?

Cheers

russellfl,
It is likely that the existing foundations will be wider than the walls so the PCC lintol will sit ontop of the foundations where they project out from the existing walls.
If you have to put in a new foundation the depth and size will depend on the ground condition and whether there are any services like drains.
end

Thanks for all your responses it's been very useful. I haven't yet checked the footings, i'm waiting for some warmer weather before I get my pick axe out. (fair weather man)

Cheers

Hi guys just one more thing if you could advise on. The existing cavity wall endings where the garage doors fit have obviously been closed off will I have to open them up to join the new cavity wall under the new window or can I join the new wall to the existing walls using wall starters and seperate cavity insulation?

Cheers

russellfl,
It would be unusual to have cavity walls on a garage but if you have it's better to open the cavity and link it through under the window.
end

Thanks stonyboy they are definately cavity walls either side of the garage doors. Will take your advice and open them up.

Thanks for that

Thanks for all your responses, though due to illness i have had to "bite the bullet" and get a professional window company in to do the conversion. it cost me just under £2k to have a floating floor and new french doors in place of the old garage door, i'm well chuffed. A mate of mine is doing the plastering etc to finish off.

Cheers

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