Old lean to extension options...

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My bungalow has a single story lean-to type extension that I wish to upgrade and I would love to get some opinions. It has been around for ages, still has the polystyrene tiles on the low ceiling etc. and is looking like a very well executed temporary addition.

My dream would be to continue the kitchen roof the whole width of the house, break through into the small square kitchen (original protruding part of the house) with some nice bi-folds for a nice big room, but I have no idea how deep the foundations are, as if they are pitiful, then maybe a glass lean-to conversion?

a) how do I find out the depth of the old foundations as the whole house is surrounded by concrete, and what must they be to meet modern regs for a full tile roof etc.
b) has anyone done anything similar and can provide approx costs they paid
c) any images would be great!

Thanks all, Rob.
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My bungalow has a single story lean-to type extension that I wish to upgrade and I would love to get some opinions. It has been around for ages, still has the polystyrene tiles on the low ceiling etc. and is looking like a very well executed temporary addition.

My dream would be to continue the kitchen roof the whole width of the house, break through into the small square kitchen (original protruding part of the house) with some nice bi-folds for a nice big room, but I have no idea how deep the foundations are, as if they are pitiful, then maybe a glass lean-to conversion?

a) how do I find out the depth of the old foundations as the whole house is surrounded by concrete, and what must they be to meet modern regs for a full tile roof etc.
b) has anyone done anything similar and can provide approx costs they paid
c) any images would be great!

Thanks all, Rob.
You find out the depth of the foundations by digging a trial hole. The depth of the foundation isn't really the issue when increasing the load - width is what we need to be concerned about. I can be pretty sure though that considering it's a single storey extension, the load won't be increasing by enough to make a significant difference. The depth probably doesn't comply with current regs, but that's not an issue if you aren't planning to knock the extension down - as long as the foundations are stable and no evidence of cracking or other movement.

Depending on the existing foundation depth and loads you may need to install some pad foundations either side of the new bifold door opening.
I personally think it would look good either by mirroring the existing roof on the RHS and having a small flat section in the middle, or by mirroring and running the front hip the full length, with a flat section between the ridges.

No idea on costs as prices are definitely going up and costs can vary significantly depending on where in the country you are.
 
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New foundation depths will normally be 1m below ground level. That's what you would allow and not worry about the existing.

Build costs may be running at about £2k per m2 nowadays. Demolition and internal alterations may add a premium, but work on 2k for budget until you get actual quotes to a detailed specification.
 
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New foundation depths will normally be 1m below ground level. That's what you would allow and not worry about the existing.

Build costs may be running at about £2k per m2 nowadays. Demolition and internal alterations may add a premium, but work on 2k for budget until you get actual quotes to a detailed specification.
Where did the OP say they were knocking down the lean-to, or extending? They just seemed to have the idea that if they change the roof they would have to rebuild if the foundations don't comply with current regs. They wouldn't have to do anything to the foundations as long as the foundations are wide enough to carry the load
 
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i built an extension on old conservatory foundations. BC asked for trial pits on each elevation, came and had a look, and confirmed they would be happy with what was already in the ground.
 

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