You will need to get quotes for actual costs and it will depend on what work needs to be done. I

Thanks, I guess I was hoping someone has done similar and can give an idea of what to.expect. hard to.find tradies who.have time to.quote.

Are you talking about the waterproof membrane under the slab? Or waterproofing wet rooms?
This page has good info on converting a shed to an approved dwelling
https://www.devcert.com/shed-houses

how can you have a converted granny flat that now needs a DA unless a conversion has been done illegally?? more detail is required but be careful about the specifics of what you (and rule makers) mean by Granny Flat in your local area as the rules are different depending on the expected purpose and what is OK for a rumpus room or workshop with bathroom may not be legal for a self contained accommodation that you may want to offer to tenants and this will be even more important if the building already exists

There are thousands of backyard situations like this, and we are doing the right thing with a retrospective DA. My question is about costs, there will be no issue re approval, I've already sorted that. We are very clear on Councils rules, hence my specific questions above.

the last time we built a granny flat (ours was called a dual occupancy) the Council fees were about $5000, the architectural plans were about $2000, retrofitted firewall and door were about $3000, engineers slab design about $2000 but all our other costs were based on a new 100 sqm building and unless there is someone nearby who has done recent similar work to yours the best costing will have to be based on specific quotes for the work you need to be done but i would expect total to be much more than $10,000

Excellent information, thank you so much. I don't have much choice but it's great to have a rough idea. Very hard to get quotes these days. Can I ask what the engineer slab design involved ? My job will involve lifting the flooring and doing a membrane over the slab.

we've had several new slabs built over the last few years and each time the engineer inspected the grounds and took soil samples as well as designing specific thickness and extras for the slabs two of which involved extra underground concrete piers on sloping sites ..we've also had an engineer inspect and design new floors to enclose a room over two separate old concrete verandahs ..one of which involved removing the original concrete and starting new and the other suspended slab had a 10cm slab added to raise the height to match other floors (and assume that would have also included some waterproofing) ... we've also had engineers inspect and advise about structural changes for renovations and advise about cracks in an old double brick building and each time price was based on hours of work and i can't be specific but assume at least $1000 for basic inspection and taking photos (maybe an hour or two on site) plus they need a copy of any existing and proposed plans so a few hours for off site research and a written report with plans and recommendations for any new and/or remedial work and each job will have individual challenges

Hi Vivianne, just wondering how you went with this. I've been working with a builder trying to better understand what sort of questions/answers would help people like you trying to navigate council approval.

Is there anything you are still trying to work out, or could you tell me areas that were really difficult in the initial stages of your planning process? This would be a huge help, and hopefully will be a huge help to others like you in the future.

UHI Alistair, I've only just submitted the first thing to Council , to obtain a building certificate. It's all difficult! And everyone gives different advice. For example, I only found out recently that my Council is apparently very strict on the 60 sq m rule for granny flats. But the old garage is 70 sq m. Some say I'll never get the ok, others say I can call part of it storage by putting up a temp wall, and reduce the area . Also that I didn't need to hire a town planner for this kind of job. Many other questions to come, I'll try to update as I make progress.

Thanks for the update! It seems like there are many like you struggling with the council laws mainly...thanks for getting back to me so quickly

Hi all we are in the situation of getting the approval to convert a double garage into a habitable space in Lavington nsw.

We had done all the interior renovations kitchen and bathroom, but we need to get th eactual approval. Does anyone knows all the procedures and the cost? We had find someone who is willing to do it, but is not giving us any cote or an approximate of the cost.

We will appreciate any advice in order find a solution for this matter.

Thanks