View Full Version : Building an Underground Cellar/Room
29th Oct 2011, 09:55 AM
I am looking at building a semi-underground storage area under my deck where my above-ground pool used to be. This room will not be attached to the house at all. It will be around 7m in length and 3.6m wide and around 1.9m tall.
At its deepest point it will be around 4-5 feet underground and around 3 feet at its shallowest point.
On top of this structure I will have the deck.
I want some guidelines on how to build such a structure and/or someone in Melbourne who could look at it. Would your average builder be able to tackle this job? Doesn't seem that hard.
Main issues would be drainage, waterproofing, load on walls, roof construction (I want it to be solid concrete that could support a deck on top) and so on.
Looking for some knowledgeable people on this type of thing.
Any help would be appreciated!
29th Oct 2011, 11:05 AM
with out seeing any form of drawings, i'd probably recommend blockwork for your retaining walls/internal walls and then some bondek over the top to carry your slab. an engineer would probably be required to draw it up. hope this helps!
29th Oct 2011, 11:23 AM
My other posts mentions a few products and ideas on this topic, although I think Kryton would be the pick.
responding to your private message:
I would do it myself.
If that has any significance?
You should use an engineer but I would not, only because I feel comfortable doing my own thing.
Any decent builder could do; most builders are competent.
There are many ways to skin a cat.
I doubt many would be aware of the many products available to make water proof.
Dictating to builders products and methods to use is never easy.
To build what you want is easy.
To build it for a price is the key.
29th Oct 2011, 05:21 PM
Hi guys and thanks for the responses so far.
I have added some images to give you an idea of the area I am talking about. I don't have any drawings at present but basically I am thinking of some kind of rectangular structure that would be built into this hole. Would need to dig it out another foot or so.
Any special consideration as to the slab?
What are the main points to cover?
29th Oct 2011, 06:22 PM
I guess I'm a little lost.
What is your idea?
You have a hole in ground and think a cellar would be a good idea to fill in the hole.
As mentioned on your other thread cheap to fill in hole with some fill in the area.
Never cheap to get rid of fill so just wait to see whats advertised on gum tree or the like.
Cellar will cost $100 per square meter plus labour plus roof and slab.
A 5 ft cellar would be a pain.
Anyway to answer your slab question.
Just do high mpa, plastic under, and cure well cover and keep wet 28 days, maybe add some silica fume or metokaolin (spelling a guess).
200mm no footings 2 layers of f72 but you need a soil test.
30th Oct 2011, 01:56 PM
a 1.9m cellar - some 1.5m underground some only 900mm ie: not all underground. As the pics show the key will be drainage or you'll end up with a tank (or a concrete pool!) not a cellar. You could in fact do it using pre-cast sections such as those used for box culverts Rocla : Stormwater : Box Culverts (http://www.rocla.com.au/Products.php?id=2) which can lock together and for which ends are available too, but not cheaply. It will need to be strong so reinforcing mandatory whether blocks concrete or whatever. Many make the mistake of looking at the in-ground pool walls and how light a structure they are forgetting that it was the water on the inside which resisted the forces and kept the pool in place. This is one of those things that seems like a good idea, and might be, but will need a) good design, b) good build - and council approval. And will not be cheap even if you do the labouring (which is not 'free' either).
30th Oct 2011, 02:57 PM
Would your average builder be able to tackle this job?
I doubt it to be honest.
What you're proposing to do is a bit different from building a freestanding structure above ground.
Factors like moisture, drainage and retaining the ground around the cellar, as mentioned by Bloss above.
Plus the plain "awkwardness factor" will probably put a lot of builders off.
While a number of people will be able to do it I think it's more a question of if they want to do it.
You might find that those who show an interest in doing it might jack their prices up, so I'd advice getting a number of different quotes to compare.
Also the whole approval side of things could be tricky.
I have no idea what the regulations are for an underground structure like this one, as I'm not a builder, but I imagine there would be lots of strict guidelines.
Others might be able to confirm this.
Doesn't seem that hard.
Arr, um... well.... actually it does.
18th Nov 2011, 05:59 PM
Frankly, if you're going to all this trouble to get a ceiling of 1.9m, I'd spend a little extra (dig a bit further) and go for a ceiling height of 2.2 or 2.3. As for the construction, perhaps consider Dincel for the walls, as they are self-sealing (no additional waterproofing required, although you can always silicone the joins) and pre-stressed concrete beams such as from Ultrafloor.
I priced this stuff a year or two back for a basement, and it was cheaper to go down a floor than up. :)
19th Nov 2011, 12:47 AM
As for the construction, perhaps consider Dincel for the walls, as they are self-sealing (no additional waterproofing required, although you can always silicone the joins)
I have used Dincel a few times now I love the stuff.
19th Nov 2011, 12:01 PM
Maybe you could talk to ppl who build fire bunkers? After the bush fires things changed a bit I think?
4th Jan 2012, 03:20 AM
Hey guys, have been looking to do something similar under my house where i dont have to excavate because i have a huge amount of crawl space. stumbled accross this which was posted last night. might help you out design wise and give you some ideas. definately gave me some ideas to think about.
Free Inexpensive Diy Underground Spiral Wine Cellar Plans & Ideas - WinePress.US Winemaking and Grape Growing Forum (http://www.winepress.us/forums/index.php?/topic/49649-free-inexpensive-diy-underground-spiral-wine-cellar-plans-ideas/)
4th Jan 2012, 09:53 AM
The link above is a bit of a fizzer....looks like you need to be a member to access the plan.
4th Jan 2012, 12:25 PM
Here are the pictures from the site: URL's
6th Feb 2012, 02:03 PM
I have just fisihed some thing like this.
2.4x2.4 internal and 2.4 high.
pour slab with starters then block then core fill with reo then bondek with steel door fram casts into the pour.
as mentioned your bigest problem will be drainage. Mine was on a hill so i trenched a drain from behind the room under the slab and down the hill so gravity does it for me. you';; need a pump.
water proofing will also need to be done very well (even the pro's have leaks).
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