Building Dispute: 500mm missing from top floor

We are building a new place, duplex with a flat roof. The house was meant to have a 500mm overhang on the top floor and the concrete slab was laid without factoring this in. Engineer's drawings factor the overhang with a cantilever and architectural drawings confirm the top floor is longer than the bottom floor.

Our builder is arguing that there was no dotted line in the plans to visually show where the building line should have been and told us he sought legal advice - telling him the architect is liable. We feel it is an implementation error as the plans visually show the overhang and if there was any confusion they should have clarified with the architect.

The house is double brick and has since been rendered, venetian blinds put in. Didn't think that as an owner I would need to measure every room. Any experience from people in getting fair trading involved? Not sure how quickly someone can come onto site and order a rectification order.

Thanks in advance!

The builder obviously has a full set of working drawing. That would include dimensional drawings of all floors, elevations, cross sections, details and engineering drawings that would all indicate that there was an overhang of the second floor. They form a substantial part of the contract between himself and you.
He has absolutely no leg to stand on. He hasn't built the house you have contracted him to build.
Get your own lawyer who specialises in building to draft up a letter putting the builder on notice. They have failed to fulfill the contract and therefore are responsible.

The rectification is another issue. Cantilevered slabs typically have shelf lintels cast into it them and reinforcing running through the slab to support it. You'll need some serious engineering guidance to make sure it is rectified correctly.

Thank you, chippy! I feel we are being gaslighted by the builder and don't know any better. If anyone has any recommendations for good lawyers in the Sydney area, that would be greatly appreciated.

I know hindsight is a wonderful thing, but the upstairs formwork and reinforcing should have been inspected before the pour to make sure it was constructed to detail.
That inspection would have picked up that the formwork was not built as per the plans. The formworker should have picked it as well.
I'm amazed that someone somewhere didn't pick it up way before the second floor brickwork was done. Even the bricklayers should have picked it when they set out the second floor. The roof wouldn't have fit as it would have been bigger than what is actually there.
I'd definitely get your own legal help as something seriously wrong has happened. Either the builder has just stuffed up and continued to roll with it or there is something not correct with the plans he has been supplied.

That should have been flagged at so many stages, by all of the trades
Was there not a construction & engineering section detail through the suspended slab overhang?
That part can be demolished and rebuilt make sure it's done properly
Cheers
Chris

Yeah, I agree. I reckon the builder misinterpreted and when it was flagged to him he decided it was a flaw in the architectural plans and told people to push on. This is what makes this whole thing so disappointing. Thanks so much for your insights on where things should have been picked up in the process. It's been a huge help.

Thanks for your response, Chris. Good to know you share the same sentiment. All I know is that the structural engineer had drawn the right elements in his plan to factor in the overhang. As you can imagine, we have run out of positive intent and now realise the builder has perhaps prayed that we wouldn't pick up on this but it's pretty hard to miss once we realised we had half a metre missing from our WIR.

We went via CDC, so my understanding is that our drawings are detailed than average. We know anything can be fixed for the right cost...our concern is who will ultimately pay up. Our time and mental health in waiting out a long battle is also giving us a lot of anxiety while no one takes accountability.

I can imagine the anxiety you must be going through.
It definitely won't be your cost to rectify as the builder has clearly stuffed up but you will end up spending money making them accountable. It certainly sounds like he doesn't want to accept responsibility for his mistake so it will be on you to make him take the responsibility.
Building a house should be an exciting and happy time and that's what makes it so hard when things go wrong and that joy is quickly extinguished.

Let us know how you get on.

Sounds like the builder is rushing to complete and lockup.
Then they will dangle the keys in front of you and give you the option
1. Take possession of the units immediately as is?
or
2. Head to the courts where you will have a delayed hollow victory
Where the builder will have to rectify...but you and your architect will have your own court costs running into the hundreds of thousand$

No, but people make mistakes and builders find others to blame. Instead of everyone working together on builds.
Hence my great dislike for architects 3D BIM
"Software designed by artists/architects for Artists/Architects ...but they forgot about everyone else in the process"
OT The software companies must take some responsibilities, when I complained to them I was booted from their forums

Fair Trading will tell you it's a civil court matter

You need to take back possession of the site and the keys...literally you are stuck
But seek legal advice as I'm not a lawyer

Sorry there's no easy way out back to 1.
OT, Others need to make sure there 3D architectural drawings coordinate with the engineers 2D Drawings
then both have to be easy enough to follow on site. There is a high probability that the guys doing the work on site can't read drawings or fail to pick up discrepancies between the documentations, ie, 2d and 3d.
Hence the need for site inspections, preferably by the engineer as he got the drawings/construction correct .
Just another huge cost to unaffordable Housing (humour)
Cheers
Chris