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Replace old leanto with extension - foundation question
I have a single skin, dwarf walled, single glazed wooden lean-to conservatory with plastic roof and a crumbling, uneven concrete floor. It's about 3650mm wide and 1230mm deep (internally) and is falling apart.
I don't see the point of a like for like replacement or bigger conservatory, but I'd like to explore levelling it and building a basic extension, 3650mm wide by up to 2500mm deep (therefore costing somewhere in the region of £10,000 for argument's sake).
我的主要问题是约1700毫米outer wall, is a square mahole cover, 450mm x 580mm, with a combined drain junction, around 1200mm deep. There are 3 pipes: 1 x toilet / shower / bathroom / stack, 1 x kitchen and 1 x front gutter pipe. These all feed a single pipe which goes away from the house. With the cover lifted, I can hear fluids from other houses, so can only assume the public sewer is somewhere down that pipe.
My question - can I assume, that as the 3 pipes from the house are already under solid concrete about 1m deep, that this can be used as part of the footings for an extension, or am I limited to a conservatory due to weight? I will not be covering the manhole cover, but want to put the outer wall adjacent to it, say about 300mm gap betwen the wall and cover.
I hope this makes sense, I have drawn it out if anyone's interested in seeing it.
Thanks.
2 Answers from MyBuilder Extension Builders
Best Answer
hi there,
if you are right in what you are saying, and it is indeed a public sewer, then firstly you have to get written permission off of the local water board (if you are building within 3 metres of it). you will have to arrange for a contractor to do a cctv survey of your drains before and after any work carried out, and also you say that the invert level of the drain is 1200mm deep. any footing will have to be dug at least as low as this so no pressure is acting upon the drains.
hope this has answered your question
Graham
Answered 3rd Feb 2014
In the past we made a single extension and the drainage pipe ran smack under the middle of the extension it was a shared drainage system with 4 houses the main waste pipe ran under the footings what we had to do was build our footings like normal but we shuttered the pipe off so it was not in cased in concrete. We then built our walls as normal but we stopped and put two lintels in over the top of the pipe then we poured chippings into the space to allow easier drainage we then used common house bricks to build up to the same level as the breeze blocks and then carried on building like normal. Hope this helps
Answered 3rd Feb 2014
