# Forum Home Renovation Structural Renovation  Guestimates for new garage dug into sloping block

## gregnpass

Currently living in a 3b/room double garage house. We plan to convert double garge to extra living plus a study. This means we will need a new garage.
We live on a block that slopes up, with probably 2meters elevation above the street. 
Our current idea is to demolish the driveway, and dig into the hillside (my guess is approx 3m deep to allow for 2.4m ceiling and slab) to make the roof of the new garage (suspended slab) to be level with the front of the existing house. So imaging the new double garage to be where the cars used to sit onthe driveway infront of the current attached garage. I plan to use a concrete slab, besser block wall construction with waterproofing, and then a floating slab ontop to allow for a "split level" style situation above in the form of an open area with awning or whatever. 
By the way it will be a detached garage so no tying into the slab of the house or anything like that. 
Anyone done this before or have any guestimates of what a project like this would cost i.e excavation, concreting, bricklaying etc? 
Cheers
Greg

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## Eastwing

$60,000 - $100,000

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## Bloss

Depends what they hit when they dig! In Sydney that could be sandstone and the cost of excavation alone might be what Eastwing says. So guesses are pretty useless in that situation. In any case best to get a couple of real estimates for the cut (& I assume removal of fill too?) before looking at the structure. The structure might vary too depending what the geology is underneath it, but once that is known is a pretty straightforward thing to estimate.

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## gregnpass

The general soil type in the area is just clay. Iknow this from some excavation work i had done in the back yard.
You are correct in saying the cost of removing fill may be expensive but I used a guy previously that took away 10 tonnes of fill for $300 a load, so i'd probably use him. 
The alternative to this "dig in" would be for me to build a  new 1.5 car garage infront of the origninal one, but this would involve digging up the driveway, pouring a slab and joining it to the roof anyway so im not sure if there would be much difference in the price in the end.

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## PeteV

my mate did one 7m x 10m dug in... it cost him just over $80k. like bloss said though, it depends a lot on your geology. your best bet, is to get your soil test done because you will require it either way. once that is done, consult your engineer. this will help you firm up your estimates! hope this helps!

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## Markt

I am in the finishing stages of doing just this sort of thing owner/builder on the north side of Sydney.  Double garage (6.5m x 6.5m) built out the front of the house.  So far about $65k.  Major costs were: excavation $15k (7 truck and trailer loads of dirt as I dug down about 1.3m or so and 5 days excavation), $8k bottom slab, $14k suspended slab roof, $5k for bricks/blocks (block below ground, face brick above and commons for the double brick inside)  and $8k brick laying and the rest is all the extras like sand, cements, pipes etc.  Probably another $5k worth of tiling on the slab roof to finish it off.  This cost doesn't include the drafting and DA costs.
Happy to give you some referrals for the people I used.

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