renovation or KDR?

We are thinking of whether to renovate this house or knock down and rebuild. Initially we wanted to put an extension to the back of the house and renovate the house to live in. However cost has come up to the point that we are thinking whether we just knock down and rebuild. Will appreciate your input.
We were planning to knock down the back wall and put a living area+ master bedroom with en-suite in the extension (approximately 33sqm2)
Will need to renovate the kitchen and bathroom as well
House contains asbestos so that needs to be removed and re cladding done on the external wall of the house
Electrician told us wiring is very old and the whole house needs re-wiring which will cost $ 25000
So the estimate has come to
1. Asbestos removal $10000
2. Re cladding and insulation $10000
3. Extension 33m2 of the main house. Living room plus main bedroom with en-suite $80000-100000
4. Redo kitchen $30000
5. Redo bathroom $10000
6. Knock down and build double garage $40000
7. Internal wall painting and flooring $10000
Regards
8. Re wiring of the whole house $25000
9. Deck $5000
This will come to $240000 so far. I’m a bit worried there will be more surprises coming up.
We have been quoted 1600/sqm2 for new build (including council application)and we are thinking about 180sqm2. Demolish will cost about $20000. We are looking at early 300k for new build.
What do you guys think? Will a new build give better resale value?

We were in a similar situation. Our old house had been renovated and extended several times over the years by previous owner. We considered major renovation and extension as the house was double brick and very solid, but the different parts of the house didn’t match and it would have cost a lot of money. Friends who have gone down this path commented they regretted not doing KDRB as the house just didn’t match even after spending a lot of money. In the end, we chose to start from scratch and KDRB.

Are you particularly fond of your existing house or have aspects that you want to retain?

I can't recommend because I don't know your situation, but we had the same dilemma & decided to KDR as well. Even spending all that money, you end-up with a compromised floorplan because it has to work around the old house - even if you remove/move walls etc.

Don't forget to factor in resale unless you expect this to be a "forever house", a new home is almost always going to be worth considerably more than a renovated one of similar size.

I recommend you get Preliminary BIM 3D Sketches and data for renovation and KDR and compare the total build costs (ie, materials, Labour, time, etc), ask for Data & Proofs, If you are on a difficult block include the Engineering examples here
Site cost fixed price Reno
Slab and formwork cost new Build
LOL, How many times have I heard a salesman, Builder, contractor say
"Its $10k for this, $20K for that and add another $15K here...LOL all together $65K
Make sure you don't miss out items/build elements.
hth

I would ask yourself, do you love your existing house?

If keeping your existing house and building the extension to the back results in your dream home, then by all means do that. If the extension your want to build onto the house is actually a bit of a compromise to the whole project, then KDR seems like your best solution.

The other advantage to a KDR is that the energy rating of the whole house is likely to be a lot better than your existing house with an extension. The downside to the KDR is that you have to find somewhere else to live in the meantime (not sure if you are living there already). The estimate for your extension at $240k does seem a bit high, although I guess better to budget for more than not enough (but I would get some more quotes).

Another vote for KDR. My mate and I live in the same suburb. I went with KDR and he went with a large renovation. Yes I ended spending a lot more, but at the same time i'm a lot more happy with the final result. He tells me all the time he should have just started from scratch and would have been more than happy to have spent that extra money in retrospect.. But yeah, every case is different which most guys above have already covered the pros and cons.