Anyone Put A Workshop/Granny Flat Underneath A Deck?

Yes, I've got a rough quote from a building designer who said very roughly $80K(ish) for what we want to do. This seemed a bit high to me. No biggie - if we can't have a workshop or granny flat underneath the deck, we can build elsewhere as we have plenty of space, just seems a waste not to use it given that we want a deck anyway.

But am just wondering if anyone else has done what we're thinking of doing and if so, how much:

1. Putting a big deck on the house running the whole width - would be about 20m x 2.5 metres (I'm making these measurements up a bit because it's dark and I can't go outside to measure). The house is elevated from the ground so the deck would be too.

2. Putting a workshop or possibly a granny flat underneath the deck given that there is space underneath the deck. We'd have to excavate though as the space wouldn't be high enough to stand up unless we dug down.

I would say the reason for your expense would be because of the excavation? It does seem pretty expensive and that's the only reason I can see for it being so high?? Although, I'm no builder either lol. I'm hoping to get some quotes for a deck and some reno's myself soon....!

Is is just the granny flat he has quoted on, or additional works? Just wondering as I suspect you are probably in a fire overlay area and the new building regs are very strict. As result the cost of doing anything has increased, plus it often means if you renovate your place you need to bring other parts of the house up to spec.

2 years ago we got a quote on extending the living area and adding a bathroom to our bedroom and it came in at $60,000. That was just getting it to a a basic point, as we were going to do the final fit out.

It was a very rough quote Astrid - came out and had a look - told him that we wanted a deck, with some sort of space underneath. At that point we were undecided about what the space underneath would be used for - whether it would be for a garage plus workshop (eg. quite rough and ready) or a granny flat. We would need to pay $4K for a better idea of price with drawings etc. which I'll do, just not with that guy, who had the personality of a slug and if I've learnt anything over the years it's that you have to get along with your contractors.

So ... just putting this out there. Will go to another architect within the next few weeks and weigh up our options which boil down to having some sort of usable space underneath the deck and hooking into the house's utlities (ie. gas, plumbing) but copping the cost of excavation or building a new strawbale workshop/granny flat at the bottom of the garden which we thought would entail bigger costs to get plumbing, electricity down there but have since done some preliminary research into making it self-sustainable with solar panels, composting toilet etc. etc. We could also build a weatherboard cottage with a kit but strawbale looks like it would be cheaper to heat and cheaper to build.