Site Cost Shock

We have just embarked on the journey of building a new house and have decided to go with Clarendon Homes in NSW. We finally received the tender recently only to be shocked by the site costs.

Some background....we have a flat site (barely 0.2m fall) which in most cases be ideal for a new home, but it is situated in a flood zone. Specifically under the 100 year flood level. To reduce the risk of flood, the local council has 'encouraged' new developments to be have finished floor levels (FFL) with a freeboard of 0.5m above the flood level. This means the the FFL of our proposed new house needs to be approx 1.15m.

Looking at Clarendon's tendor this has added ~82K to our site costs (we expected an increase but nothing to this degree). Here are some approximations of the additional costs (on top of the standard site costs)

1. Extra fill to be carted in 10K
2. Drop Edged beams all around the house 42K
3. Integrated retention walls 2K
4. Upgrading to H class slab 4K
5. I need to conduct my own flood survey 3K
6. A provisional allowance for screw piers 15K
7. Stairs (front and back and railings) 6K

My Questions
a. Is this reasonable for a house ~40 squares
b. What are my alternatives? Would it be more cost effective to have a suspended slab?

I don't know about the amount of the costs but if the the costs are for a single storey a 2 storey house 'may' be a cheaper option as it will require a lot less fill and foundations

Absolutely ridiculous. You can get fill for free. Getting rid of it is costly. Get the price for a drop edge beam from someone. It would only be about 1 metre deep, which is not a lot of concrete and steel.

I hope you haven't paid Clarendon more that about $1500 at this stage as you may need to try others. Clarendon also need to know you are prepared to walk away otherwise they'll just charge you four times what it should.

I would personally say to Clarendon, find a way to do it for $24k or we're out of here!

I think the builder is saying they do not want the hassle of building on that site without saying it. You have the soil test you can take to other builders and maybe get it cheaper but you may have to have a stump house to reduce the cost.

I had 17 truck loads of rock carted away and 260m2 of sand delivered, levelled and compacted for $7000.

I would be telling them to try a bit (lot) harder.

Other option is to do it on a do and charge basis. Companies definately over estimate for groundworks. Or take it out of the contract and just have them do from the slab upwards.

Do and charge is dangerous. It's the equivalent of handing over a blank cheque.

Another builder just quoted us $60K to raise another house similarly sized. so there is going to be some pencil sharpening if C is going to get our business.

If the council are just 'encouraging' developers to do this, is flooding a risk you'd be prepared totake? Otherwise mabe take another look at the block. Our builder wanted to do a 1mtr cut and fill diagonally across the block which was going to need more retaining walls that they wanted to charge me an arm and both legs for until I pointed out that they could do a deeper cut, no fill would be required and more of the slab would then be on original ground.
After this suggestion, the guy at the builders office was "oh yeah, we could do that too" so clearly he hadn't thought about what else could be done, just what would get us to spend more. The retaining wall I built with the bigger cut only cosy $1200 in rock...

Well said phippsy. Builders don't want what's cheapest for you, but most profitable for them.

This is why it's important to not spend any money until a final price is obtained and keep looking with mor ethan one builder. You've got to keep the builder competitive.