Haf63

Quick update - structural engineer checkout out my garage and basically said the best route is to build a pillar on the inside and run a steel to the end of the garage which will support the first floor. The existing garage wall and structure looks ok to stay as is. Good news - other than will need to dig a 800x800mm hole inside the garage for the pilar. He also suggested I contact the house builders as I purchased from new 25 years ago and they may all be able to give me a copy of the structural documents so will give that a go as well.

I am in warwick (CV35)

Thanks and I am calling in a structural engineer to have a discussion - just trying to track one down

Appreciate the spelling correction so no excuse needed. The wall is made of single house facing brick with a few pillars on the inside - not sure what you bean by 'wall stiffening' but sounds sensible

Thanks for the feedback and I will see if I can dig to see depth of foundation but would hope the 'new build' guys would have at least done the minimum thickness to get me to 1m. I wasn't aware of the width being an issue as this looks about 15cm overhang on the outside. The inside is a concrete floor so don't fancy digging that up but there are some blocks pillars on the inside - look like a single blocks mounted on their side against the outer brick wall. If the inside is also 15cm past the block then that would give a width of 500mm. Lastly I went to see the neighbour who had something similar done back in 2010 and he said they did absolutely no foundation work at all (didn't even check it) and simply put a steel on top of the block pillars in the garage so the outer wall was a simple continuation of the existing wall and they build the blockwork for the first floor onto of the steel. They also had a steel front and back on existing garage pillars - so it seems like there is an option to use steels to support the first floor regardless of the garage foundations. Obviously I am leaving this to the architect and structural engineer to work out but my builder is advising me that his quote would be lower if the existing garage stays mainly intact and he doesn't have to do lots of foundation work hence I am educating myself before I have this discussion with the architect. Appreciate the advise so far.

Just a quick update. I dug a test hole to check that foundation and it starts at 800mm below ground and I assume it will be 300mm+ after that. I would hope this is enough to be useable and so keep the existing garage external wall and build on the inside

I have a 1997 new build with an attached side garage and have got planning for extending the garage backwards to match the rear of the house and add a first floor with a dorma at the front which will be built into existing garage roof. I am reasonably familiar with extension builds but usually starting from the ground up. In this case I would really like to keep the existing garage wall along the length but its a single skin facing brick wall with a couple of pillars along the 5m length (the front 2m will stay as garage and the extension will add 4m to length). I know that I will have to dig and check foundation but suspect its unlikely to be suitable for building regs. I know that demolish and start again maybe the best option but wanted to explore the options of underpinning and a steel frame. I believe underpinning is pretty expensive versus demolition so was thinking of using some sort of steel frame around the 3m of the existing wall being used so it can support the first floor. A normal foundation can then be dug on the inside for the inner block work and insulation. Or am I being a bit nuts and should just knock down the wall where the room starts?