Underground room build, Need help Options

[cf]

hi stealth

actually i dont think he'll have this problem as he's above the water table and on what is effectively a slope, albeit one that has reinstated ground levels.

i recently did a total renovation on a house that has a few similarities to this idea, at the front of the building one floor is underground but coz the house is built on a slope at the back the lowest level is exposed. so at the front it looks like a 2 storey house and at the back you can see 3 floors.
i completely tanked the bottom floor as it was uninhabitable due to the amount of water leeching through the walls, but using a sump system was unnecessary due to the fact that any hydrostatic pressure could be dissipated through the exposed substrate to the rear of the building.
as long as water can leach through the existing retaining wall in this guys picture there wont be a need to pump it away.

i can see that some people dont believe there will be a problem with damp in the hole, all i can say is my mates underground g/r was on a hill 20 feet above the ground level outside his house,well above the water table, and after one particularly wet spell he lifted the trap door and his plants were floating around in two feet of water.
once it stopped raining and we had a couple of dry days the water level dropped but he has abandoned the room and grows in his roof space now.

when it rains a lot of water is absorbed by the ground and it takes a while for this to reach its natural level or drain away to underground aquifers, until it does that it will find areas of low pressure and move towards them wherever they are. if you dig a hole in the ground and it rains chances are that hole will fill with water even if you prevent the water from actually entering the top of the hole, i've spent too much of my life digging trenches for cables, post holes and footings and have seen this again and again.
like i said... constructing this thing is a major task, waterproofing it is not

[d|t]

whats the point now though above ground

police arent gonna say "where is it boys"

[Rambone]

I'll be very impressed if this ever materialises.


Get a picture of the finished product and ill happily give you £500.

Thats how sure I am this isn't going to happen or if it does happen it wont 'work'.


Just my 2 cents.



p.s. Im not being a dick about it I just REALLY cant see this happening.

[Stealth67]

hi stealth

actually i dont think he'll have this problem as he's above the water table and on what is effectively a slope, albeit one that has reinstated ground levels.

i recently did a total renovation on a house that has a few similarities to this idea, at the front of the building one floor is underground but coz the house is built on a slope at the back the lowest level is exposed. so at the front it looks like a 2 storey house and at the back you can see 3 floors.
i completely tanked the bottom floor as it was uninhabitable due to the amount of water leeching through the walls, but using a sump system was unnecessary due to the fact that any hydrostatic pressure could be dissipated through the exposed substrate to the rear of the building.
as long as water can leach through the existing retaining wall in this guys picture there wont be a need to pump it away.

i can see that some people dont believe there will be a problem with damp in the hole, all i can say is my mates underground g/r was on a hill 20 feet above the ground level outside his house,well above the water table, and after one particularly wet spell he lifted the trap door and his plants were floating around in two feet of water.
once it stopped raining and we had a couple of dry days the water level dropped but he has abandoned the room and grows in his roof space now.

when it rains a lot of water is absorbed by the ground and it takes a while for this to reach its natural level or drain away to underground aquifers, until it does that it will find areas of low pressure and move towards them wherever they are. if you dig a hole in the ground and it rains chances are that hole will fill with water even if you prevent the water from actually entering the top of the hole, i've spent too much of my life digging trenches for cables, post holes and footings and have seen this again and again.
like i said... constructing this thing is a major task, waterproofing it is not

Hi cf, been a while

Like you say, if he can release the water pressure from around the construction without a pump all good and well<(scuse the pun ), but if it doesnt release it quick enough during torrential downpours, he could end up with a pond like your mate.

Could really do with some pics, is there any pics ?

[ragemonkey]

Could really do with some pics, is there any pics ?

Had to mess about with a few of this pics , jsut to make it not too obvious ;] . And remember this is a work in progress its by no means finished yet .


















The type of soil thats being dug out

[Rambone]

Ok I take back that last post. Looks like it is happening. I still dont think it will work though. But hey....prove us non believers wrong!

A lot of work yet to be done. The 7th picture really looks a bit sketchy. Dont think i'd like to be stood next to that mud wall

[podgy]

Go for it vato...

[cf]

hey ragemonkey you've been hard at work!

that looks like quite crumbly sandy stuff you've been pulling out of the hole, and considering you have the weight of a shed on top you need to get some concrete down and build some walls before your hole starts to change shape dramatically.

please dont think that it will stay that way for ever just because it has for few weeks, it needs shoring up at the very least and really you should be building an underground 'room' like i have described.
please get this done asap if you are in that hole and something gives you might not make it out in one piece .... am i sounding a bit over dramatic? i hope you dont think so, a lad died whilst digging a hole next to the road a few hundred yards from my old house , the hole was only 6 ft deep and the side gave way when he was bent down in the hole and despite the best efforts of his colleagues he didnt make it.
sorry if this sounds scary but i've seen enough nasty things on site over the years to know that youre at risk

[rebirth]

that was a lot of digging congrats thats gotta be at least half the work done! rebirth

[ragemonkey]

1. cast a slab in the bottom of the hole.
to do that you need to put down some hardcore (broken bricks etc) 100mm deep and then smooth off (blind) the surface with sand and then mix up and pour in concrete 100mm deep , skimp on this and the bottom of your hole will move about when the ground dries out / heats up with the heat of your grow.
you should put in a dpm (damp proof membrane) on top of the sand and before you pour the the concrete, make it a big piece and fold the remainder up the walls to ground level

2. build walls with concrete blocks on the edge of the slab with the dpm between the side of the hole and the back of the walls and back fill down the back of the membrane with sand.

3.put on a roof?

you can do it on the cheap but if you dont completely waterproof you will end up with an underwater g/room...i've seen one and if you dont make a solid structure it will subside sooner or later.

this is a lot of work but if you have dug a 6 foot cube in the ground youre obviously not shy of a bit of graft

If i were to follow this plan how much would all the building materials costs , I expect concrete and bricks to be quite pricey?

[Rambone]

From the position your in now to a finished 'underground room' (without grow equipment just the basic structure of room) I reckon your looking anywhere from £1500-£3000 depending on what problems you encounter along the way. Also price depends on if your getting contractors or doing all the work yourself.


Boy, and im worried about standing on the flooring I put down in my loft Kind of puts my flooring situation into perspective.

[cf]

If i were to follow this plan how much would all the building materials costs , I expect concrete and bricks to be quite pricey?

they arent cheap but i cant really see another way of doing it properly.

you can work out how much it will cost by estimating the quantities and then giving your local builders merchants a call.

for the concrete if your floor is 2mx2m x 100mm then you'll need just shy of a half a cubic meter of concrete, best to buy in ballast and a few bags of cement and knock it up yourself


anway you had £250 ..and now Rambone owes you £500

(edited coz i cant reckon properly)

This post has been edited by cf: Jul 16 2008, 02:57 PM

[Leprechan Sweet ...]

Hey,
I just finished digging a 6x6x6 ft hole in the ground or damproofing but with no luck :[.

This is turning into an interesting thread
Looks great but I have read a lot of stories about damp cellars being unsuitable for humid plants to grow. Hope ya can make it work.

[growndome]

If i were to follow this plan how much would all the building materials costs , I expect concrete and bricks to be quite pricey?

anway you had £250 ..and now Rambone owes you £500

haha


thanks for putting up pictures it does look impressive. I really hope you manage to sort this and sort it safely and well because it does look like a cracking hole you have and obviously a lot of work gone in already.

[Keye]

I tell ya what, a big big big round of applause to you for digging that hole.

I feckin' hate digging holes for fences, let alone that monstrosity. And with nice straight walls too!

Well done.

Not over yet though. I personally want you to listen to the advice being given here. It's worth its weight in gold.

Keye.