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 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?
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.
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?
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.