Extending underground

Seve OB

I seen a program recently on the box about London homes extending underground. some unreal jobs, going ridiculous depths.

Was wondering if that trend has arrived in Ireland at all?

Would be very interested as I'm considering an extension, 2 story basically the width of the house out back, but if we could go underground it would make it a lot more interesting.

2 ways of looking at it. go straight down and out from our existing back door where we are thinking of extending
or what they were at over in London, and going right in under the existing house (obviously cost a hell of a lot more)

end of the day, it would probably be cheaper to move, but we like where we are. busy housing estate in Dublin suburb.

wersal gummage

Can't possibly make any financial sense in a housing estate. Would think this is something for someone living on Fitzwilliam or Merrion Square type of place in a house worth several million.

kieran.

Cost is seriously prohibitive expect it to be a very least 10 times more than building overground.

Metric Tensor

If you have to post here asking about it you can't afford it under the existing house! Unless your butler is posting for you?

Anything under the existing house is going to be part of a project in 7 figure territory.

It would obviously be cheaper if you just want to install a basement under a new extension you are building out the back but still substantially more expensive than anything above ground and a bad economic proposition unless your house is in a very valuable location.

Seve OB

im just curious is all.

would like a decent play room for the kids, maybe somewhere I can whack a golf ball into net on a cold winter evening, snooker table etc. underground is the only way I could get it in. I know its gonna cost more, I already said that. just that we like where we are, so starting to look at our options as if we build, cant see us ever moving

loyatemu

Johnny Ronan's been trying to do something similar in town:
https://www.irishexaminer.com/breakingnews/business/johnny-ronans-25m-plans-for-underground-office-extension-refused-by-an-bord-pleanala-857670.html

we've a massive void under our house for the suspended floors - it's about 5 feet under some of the rooms. I've often wondered if I could dig down to turn it into a basement, probably not a good idea structurally.

Lumen

Colin Furze has an amazing series of Youtube videos on building a bunker under his garden.

I'm not entirely sure they'd meet Irish planning or building regulations, but you get a sense of what's involved.

riclad

Theres a bbc documentary about underground extensions ,in central london, where a house costs millions of pounds ,
it makes sense to make a large basement .
Its very expensive, only the rich can do afford it.
It makes no sense in ireland where houses are cheap at least compared
with central london.
It might make sense to maybe build maybe part of an extension underground
,i,m not an expert but ,id leave space between the extension and
the house as you do not wish to risk weakening the house foundations .
It might make sense if you could do part of the work yourself ,
eg blockwork, putting in doors windows .
heres the link

https://www.youtube.com/watch?v=sLJ0zZQb9x0

In ireland its usually cheaper just to build an standard extension if you need
more space.

Seve OB

Lumen wrote: »

Colin Furze has an amazing series of Youtube videos on building a bunker under his garden.

I'm not entirely sure they'd meet Irish planning or building regulations, but you get a sense of what's involved.

yea I've watched that before
the apocalyptic bunker I think wasn't it. something else

Metric Tensor

It's totally possible and basments are built all the time, in some cases to extremely high standards.

Assuming you can get planning permission, which isn't guaranteed, the cost will be large. But if you have the money - more power to you.


Structure will be your primary concern - make sure you have a good structural engineer on board. After that natural light, ventilation, waterproofing and wet services (sewers, etc.) are likely to be the most challenging aspects. It's all doable though - you just have to budget WAY more than you would for an above ground building of the same size.


Edited to add: In the above I'm talking about a new build underground basement not under the existing building. I only know of two (although I'm sure there are a few more) places where an existing building had a basement installed under it in Ireland. Neither was a domestic dwelling and both were/are in Ballsbridge.

riclad

It would be cheaper if you could use the underground extension as an extra room with no water pipes going through it .

B-D-P--

Lumen wrote: »

Colin Furze has an amazing series of Youtube videos on building a bunker under his garden.

I'm not entirely sure they'd meet Irish planning or building regulations, but you get a sense of what's involved.

I forgot about him, You revived his youtube channel for me

DOCARCH

Ground conditions (soil type and the fact bedrock is deep down) and water table levels in London make basement extensions a lot easier than, say, Dublin (or a lot of Ireland!).

Johnnyhpipe

Definitely possible. But even if you could get the planners to go for it, a say 40m sq extension would be in the order of €1-1.2m basic. And if you’re doing a basement beneath an existing house, in reality you’ll build as big as possible, not 40m sq.

So as stated earlier, unless your butler is posting this for you, you likely can’t afford it. If you can however afford it - any chance of a fiver??

riclad

I mean maybe you could build part of the extension underground ,
maybe 10ft deep .
but not under the house ,
building basements is so expensive in ireland it makes no financial
sense for ordinary home owners .

Dial Hard

AFAIK the Goethe Institute's recent renovation included underground space. They had plenty of German federal money to play with, though.

AndrewJRenko

Dial Hard wrote: »

AFAIK the Goethe Institute's recent renovation included underground space. They had plenty of German federal money to play with, though.

RCSI build on York St went down by four storeys, iirc. Look out for the RTE documentary on the build project.