Extending a house - downwards

[kmillar]

OK, not really a 'diy' question. Our house is a fairly traditional 3 bed semi in Scotland. The upper floor has just 3 bedrooms (all dormers) and nothing else. Downstairs is bathroom, kichen, living+dining area.

Some people in the street have extended out sideways - but this means loosing the driver way and in two neighbours do it it means a gap of just inches betwwen houses.

So (you're ahead of me here I bet), How possible would it be to extend downwards? IE, excavate under the house and put in a study, entertainment room and storage areas? I don't think we'd be alowed a bedroom downstairs.

Obviously this is something for the professionals to tackle, but would it be prohibitivly expensive? Or just downright impossible?

[Rick]

It can be done, some compaines specalise in it.

Rick

[The3rd Earl Of Derby]

But only if the governing bodies will permit going below ground level? Seek advice on this before you tackle it.

-- Sir Benjamin Middlethwaite

[chris_doran]

ISTR a TV programme about this a month or two back. A major exercise to reinforce foundations, as you'd expect. A figure of =A3100k comes to mind, but they reckoned it was cheaper than moving.

Chris

[meow2222]

Perfectly possible. See the basement company for some pics. Companies like that charge in the region of 90k to give you another floor, and its fully habitable. Can be done in conservation areas too.

As long as youve got enough window area, access/egress etc, its as habitable as any other floor. Dark damp old basements: one hs to wonder why they were designed like they were.

The work involves excavating and propping the house, underpinning effectively. You need to add a storey plus whatever depth of foundation is required nowadays. Then its a case of installing doors windws and an access well, staircase, services, and making it all look nice. And your ground floor will need replacing if its a concrete slab type. Suspended wood ones can stay.

So yes its diyable, though not a small job. Just make sure your insurance is up to date :) And budget quite a bit for props.

NT

[Dave Fawthrop]

| OK, not really a 'diy' question. | Our house is a fairly traditional 3 bed semi in Scotland. | The upper floor has just 3 bedrooms (all dormers) and nothing else. | Downstairs is bathroom, kichen, living+dining area. | | Some people in the street have extended out sideways - but this means | loosing the driver way and in two neighbours do it it means a gap of | just inches betwwen houses. | | So (you're ahead of me here I bet), How possible would it be to extend | downwards? IE, excavate under the house and put in a study, | entertainment room and storage areas? I don't think we'd be alowed a | bedroom downstairs. | | Obviously this is something for the professionals to tackle, but would | it be prohibitivly expensive? Or just downright impossible?

Not sure about your area, but round us the water table is too high for that. Cellars sometimes become swimming pools and are usually too damp to be of any real use.

Take professional advice.

[Rick]

Has anyboy ever DIYed this in their spare time ?

Rick

[Owain]

Another option might be to extend the first floor sideways giving you additional bedroom/bathroom space, but leave the ground floor as a drive-through carport.

X X / \ / \ ____/ _ \_____/ _ \____ / / | | \ / | | \ \ / / |_| \ / |_| \ \ / \ \ | | |------------| _ _ | | | | | | | | | car port | |_| | | | | | | | |

Owain

[Doctor Drivel]

It can be done, but not cheap at all. Will you make back the cost? If you intend to stay in the house for many years then cost is probably not an issue. Best get a specialist company. Your existing ground floor will have to come up and the house unliveable for quite a while. You could put the boiler down there with any cylinder too, saving space up top where you need it.

One I did see was the garden excavated and backfilled, with access via a staircase in the main house. The staircase was dug under the integral garage, so not that much disruption inside. The room under the garden had about 3 foot of earth between it and the main house, so the foundations would not shift when the garden was dug out. The ventilation to the under garden room was to the side of the garden and up out of the way. Two of them at opposite sides. Of course a JCB needs access.

If doing an under garden room then installing an earth pipe is well worth it.

[Dave Plowman (News)]

It's quite common in this part of London where house prices are silly, and they generally don't have large gardens. Two being done in my road at the moment. However, they did start out with cellars - mainly for coal storage, etc.

[Doctor Drivel]

That is because silly people live there.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Rick saying something like:

There was a bloke somewhere in the North who did it with an excavator. His was the middle of a row of terraces which was on a slope. In an attempt to create a basement which would house his car, he took away all the bank in front of his house and dug down in front of the wall.

The house partially collapsed and took his neighbours' with it. Not only that, but working on the domino principle, all the houses in the terrace were affected.

Not a popular man, iwt.

[Ian Stirling]

Hmm. Random thoughts. Assuming it's similar to mine. Walls 3m*0.5m stone. Call it 1.5m^2, or 3500Kg/m of wall. Call it 5000Kg/m, and including the rest of the structure.

So, for a 20m*5m, that's maybe 50m of wall, or 250 tons.

If the wall is supported by one beam on the inside, and one on the outside, then the load per beam on the long wall is 50 tons.

Hmm. I don't know where to go from here. Can one hire a crane for a day that'd simply lift the whole structure in one, and place it on a convenient flat surface, before digging the basement and pouring foundations and placing it back on?

[Andy Hall]

At least they put the coal in the cellar as opposed to the bath, or have they stopped doing that in your area now?

[Doctor Drivel]

Matt, I don't believe you. Sarf Lahdan is full of silliness. It is noted for it. An those appalling grotty towns that surround it too.

[kmillar]

Once again, I really am not thinking of tackling this myself. I just anted to know if it was possible.

As for the wather table - I remmeber seeing a programme on Discovery about a new house being built with an underground level - the lower level had special collector units in the wall and a pump to keep the level dry. Any way, we're at the top of a hill so water table probably won't be a problem.

[Capitol]

Any way, we're at the top of a hill so water table probably

Water table can be