Waterproof air-conditioning slab

We have paid extra to have the ducted air-conditioning slab poured as part of our house foundation. The builders say it is our responsibility to waterproof the slab, they don’t offer to do it. Where do I find out how to or who offers this service. The air-conditioner is part of the build as a “free upgrade extra” from the builder.

The slab still needs to comply with the BCA
And it’s the builder resposability to comply with it

Have you a photo of the AC slab

Not quite understanding what you mean under ducted air-conditioning slab.
There are ducting pipes inside the slab and duct vents placed will be in-floor?

If the builder offers an upgrade, he should be waterproofing it too (it should be all covered by your building contract).

It looks a lot better than my situation at least you have a step down to your AC plinth

You can get some clear sealer from bunnings to maybe spray on to slab , what the life span would be I don’t know it’s not a permanent barrier
It’s a design fault really and as I said it’s down to your builder to meet the code requirements it’s not for you to come up with a solution to sort out a problem for them
Part 2 of the code states you must prevent damp and moisture entering the building
You can down load a free copy of this so you can have a read up on it
Where abouts are you building ?

Virginia in Sourh Australia

No it’s just a slab for the air conditioner to sit on, poured at the same time as the whole foundation, we paid extra for it, but in the contract it says we are to have it waterproofed, but it has the same plastic as the main slab, and has had the same waterproofing done by the white ant ppl. So I am at a loss to understand what blinking waterproofing they are talking about.

I don't think it requires any waterproofing at all (except possibly slab edge touching the ground), i.e. do you waterproof your driveway?

If you look at the photo you will see it’s connected to main slab so moisture and damp can penetrate up into main slab as there is no break or dpc to stop it

Where the moisture and damp will be coming from, I wonder? How do you specifically waterproof your driveway slab, which is also connected to the garage slab, etc.?

Waterproofing for concrete is only needed for below grade surfaces.

Your driveway slab is not connected to the house slab , if done correctly the dpm is extended through and then brought up the face of the slab and cut off at ground level
Giving you a barrier to prevent moisture / damp entering the slab
Down load a free copy of the ncc it’s all in there

Driveway connected to garage slab, garage slab - to house slab. There is no DPC between them. Same thing with the alfersco slab connecting to the house slab.

If you waterproof the edges and under your aircon slab, how do you see the dampness entering to your house slab even though they are connected?

The drive way is not directly connected to the house slab it’s poured independently with expansion joint between , if the dpm is not brought up the face of the slab it is in breach of the code unless an engineer signs off on a alternative solution
When you build brickwork you have a dpc to prevent rising damp and moister the dpm under the slab is the same thing it prevents damp coming into the slab , the slab is protected from the weather by the walls etc but the AC slab is left exposed but part of the slab so damp and moister can get into the main slab as there is no barrier to prevent it
Are you a trades person or builder ?
As I said down load the free ncc it explains it all in there
The point being that it’s the builders responsibility to build to code

I see your point here. What about patio slabs which are generally get connected to the main house slab (eg alfresco ones)? There is typically no expansion joint in between. How do you waterproof those?

I suppose they will say they are protected from weather as mostly covered over , techincally it’s not correct