Cost to build an underground garage

that's right, the house isn't built yet. I'm planning to build a couple of units on the site and just thinking of a few options for how to maximise the use of space
 
Sorry can't give you a $ figure.. but an underground car park on a level block sounds very expensive... room for 1 or 2 cars?? You'd have the cost of a sloping driveway (assuming you have enough room, keeping in mind the max slope), retaining walls on 3 sides, and a suspended deck.. not cost effective for residential stuff.
 
Nice looking homes.. may be more cost effective for the higher end. I guess you'd do your DD and see what is in demand for the area 3 or 4br, I noticed they have room for 3cars.

You could come up with a cost for a number of scenarios. Rawlinsons is a construction handbook used for quantity surveying. It may help to have plans of a similar build that you could work from.

Edit: on second thoughts, coming up with an accurate construction cost would be essential as part of the DD.
 
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A lot! I know people who have spent six figures on an underground garage/basemenet/workshop. Was a builder who did it for his PPOR so obviously what it cost him will be less than what it would cost you.

You are looking at deep excavation, OH&S requirements associated with that, reinforcements (steel etc), concrete etc.

personally I wouldn't do it on a flat block as you would be cutting so deep that the liklihood of needing a hydrolic lift system to get down is huge.
I would consider if the block was on a slope and the site is cut in such a way that the garage becomes a split level if that makes any sense.
 
thank you all for your replies.

I did some ringing around and it looks like the cost is around $200/m2 (obviously depends on a lot of factors like the type of soil etc). The slab will also be more expensive.

Still, for some projects getting a basement carpark may mean being able to fit in an extra unit so might be worthwhile.
 
it's pretty much everything: excavation, floor, walls, waterproofing etc. Extra costs would be plumbing (they usually put a pump in to get rid of the water), garage door and the house slab would obviously cost more depending on how it's designed (i.e. suspended slab).
I was told of two actual projects - one is 400m2 costing the owner $120k (they had some rock in the soil) and another one was 1250m2 at a cost of $250k
 
Here I was with a double garage in mind. I guess for a >400m2 garage that pricing seems about right. I was thinking I could have a 6m x 6m garage under a new house for about $7200. That would be brilliant :)

Just have to convince the wife that if we get around to building a new PPOR that we should build a 400m2 garage under the house because it's only $200/m2 Sounds like value to me, fair chance I would be made to reside down there too.....

Gools
 
Rawlinsons

According to Rawlinsons, if it is partly set in the ground (but gets some access to light and ventilation) then $550 per square metre. If it is fully in the ground with sprinkler system then $1250 per square metre.

I'm thinking about it for a site I want to develop... it would allow me to get six units (3x3r, 3x 2br) instead of four (all 3br).

So might be worth it.
 
I reckon it is a great idea, if you do a search on cave houses you will find many of them overseas.
Wonder what the cave houses in Cooberpedy cost to build?.
I will do an underground carpark one of these days, maybe an underground house, I like the idea.
What if you put a series of shipping containers under the ground say only around ten feet or so down, could be worth looking into in bush fire prone areas, great insulation also, probably need to be on the side of a hill or drainage/damp could be an issue.
 
thank you all for your replies.

I did some ringing around and it looks like the cost is around $200/m2 (obviously depends on a lot of factors like the type of soil etc). The slab will also be more expensive.

Still, for some projects getting a basement carpark may mean being able to fit in an extra unit so might be worthwhile.

Only $200? , impossible.
They are charging $80/m for plain concrete driveway and for a flat block you'll need a considerably long one or it will be very steep and you'll also have reinsforced slab (probably 2 of them, above and below) , piers, stairs, side walls, waterproofing etc
 
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