Are these costs reasonable?

Hi everyone,

Have been a lurker here and hope you don't mind me asking a question or two. My husband and I are building our PPR. We're building a two story on a small rear lot. The lot is level and soil is sand. We're at the point of signing contracts with our builder. Our preliminary agreement had a provisional sum of $15,000 which has now jumped to $24,000 as they have included more provisional sums. The $24k includes $7,000 for survey and earthworks $4,000 for stormwater disposal including two soakwells, $5,000 for connection to Western Power (we were told that the reason that this is so high is that WP have recently changed their connection fees). WP is located at the front of the front property and our driveway is 25 metres from the front verge to our front door. There's an additional $4,000 for dropped footings (we asked for this so we can put a small pool in after construction) and a few other smaller items.

There's no allowance for rock breaking rubble removal or de-watering (whatever that is!) However there's a PS of $2,000 to provide a crushed limestone road base and access track to the site which seems high given that the drive is already concrete so the most they could "limestone" would be the area that will be the parking circle.

Anyway I just get the impression that it's all been thrown together a bit. I know that the are only provisional sums, but I am concerned about giving the builder overly generous allowances that they will use regardless of necessity.

I was thinking about asking them to agree to cost + fixed margin for site works.

Would be very grateful for all comments and advice.

Thanks very much guys.

the numbers and items seem about right.

"de-watering" - when digging your footing, and the depth is below the water table, they have to continuously pump that water out.
crushed rock road base,
may be if the existing driveway belongs entirely to the front dwelling, not a shared access

I pay 1500+ for three big truck loads 45tonne each of gravel and a grader to level the road and rspread it after winter snows melt away,
google conveniently shows melting snow,
and takes half the road with it.