Builder has proposed performance solutions - are these ok?

We are about to build a single storey house with a major builder, and they have come back with a range of performance solutions they have asked us to sign - see below.

Are any of these not ok and should we request they remove some of them?

The 25mm slab overhang is a bit concerning as is the reduced waterproofing.

Appreciate any advice!

There are engineering details, notes, etc for structural overhangs (that's the evidence you need)
if it's not referenced in the CDs then you've got buckleys trying to sort problems out later
Pity you didn't get your own drawings properly certified before hand.
Goodluck

You need an 'expert opinion' to have a "Performance Solution" certified as meeting the performance requirements of the NCC but many other experts do not agree with many of the "Performance Solutions" that are certified.

The slab overhang topic was discussed recently in the thread I have linked below.

viewtopic.php?p=1911731#p1911731

Ideally, the frame should sit on the slab and any allowances just excuse poor preparation and workmanship. I would feel disrespected if asked to accept a 25mm overhang allowance.

A mortar mix of 1 part cement, 1 part lime and 10 parts sand is a weaker mix and inferior to the norm.

I think that Porter Davis started the reduced waterproofing 'trend' but bless their hearts, you could option for the full waterproofing at considerable cost. There was much discussion about this on a large Porter Davis thread maybe 8 years ago. A forum search using the appropriate keywords should raise the thread.

The 20mm recessed DPC also falls outside of the recommendations of the brick manufacturers but manufacturers recommendations/instructions no longer apply in the NCC.

Make no mistake, builders use certified Performance Solutions for cost cutting and to excuse poor workmanship. They are not acting in your best interest or to ensure quality.

Have you already signed the contract or paid a deposit?

As a guess, I will say you are building with Henley. Yes/No?

Is your build so highly customised to the extent that the the national construction code's deemed to satisfy provisions (that reference Australian Standards) are not appropriate. Ask your builder to explain this for each one and confirm to you in writing. Don't sign until you understand the differences and rationale for each performance solution as well checking the engineers signed validation document for each solution. Proceed with caution and an open mind!

Carlisle do the reduced waterproofing too and require annual inspections at a cost to the homeowner to maintain warranty. complete rip

H2O answered this - This is cost cutting. Have a think - material subsititutions (more sand), less materials (waterproofing, flashing etc). This all ads up over thousands of builds.

Really???

That is wrong on so many levels.

Thanks all. Yes Henley is the builder.

I want to push back on some of these knowing I won't win them all. But I think a non-negotiable for me is the weaker mortar particularly as I will have a pool next to the house and chlorinated water splashing over the bricks regularly. I assume this could wear away a weaker mortar mix?

The reduced water proofing doesn't sound so bad as it is areas that won't see a lot or any water. The shower and bath will still be waterproofed.

I don't quite understand the 20mm DPC one - would this be an issue if we end up with garden beds next to external walls, and hence more moisture?

I'm very close to just walking away on this build as they have raised prices substantially including a doubling of our slab cost from tender to contract stage.

Realistically will Henley negotiate on any of these performance solutions??

I found the Porter Davis discussion (below) but there has been a lot of other discussion since then. Waterproofing is the best keyword to use if you do a forum search.

viewtopic.php?p=1275656#p1275656

The DPC is to stop rising damp. It use to be outwardly visible but aesthetics often subjugate function.

Having a garden bed against the house is not a good idea, particularly if you build on reactive soil. You need to do a forum search on this topic as well.

Anything is negotiable (often at a cost) but Performance Solutions are now engrained in the Henly culture and work practices.

Performance Solutions use to be called Alternative Solutions. I hated the name change because having a performance option most often signifies optioning something superior.

The stated principle of the NCC is its a 'performance based' code. There is inbuilt flexibilty to vary from DTS which can be of benefit to homebuyers and builders however i would want to fully understand the alternative, see the prior validation and consider cost/benefit before agreeing.