P class soil

Hi there,

New to the forum. We have just put a contract on a block of land pending satisfactory soil test (and finance of course). The soil test has come back as P. Sounds like the block has been built up with fill due to flooding around the area.

I'm just wondering if anyone has any idea on the extra costs involved with building on P class soil?

I'm a little worried but have been told P soil is fine?

I'll add- this is our DREAM block! It has everything we ever wanted.

Advice would be awesome, thank you

Ask the developer for the level 1 certificate and if you get one, your site will be reclassified.

It might not be that big a deal. As mentioned above, if the fill was compacted to the proper Australian Standard (which needs that certificate), the land can be treated as if it were never filled to begin with. But if it is like my block (class "P" that was filled and no certificate), then yes, you will almost certainly have to pay higher site costs. In my case, for example, I have a larger number of piers, ranging in length from around a metre minimum to around 2.5 metres (my fill was around 400 mm on the three bore tests they did, but they cover themselves given they cannot test every inch of the block).

Unfortunately I can't tell you what the price difference would have been in my case had the land not had fill. The builder has built about 6 other houses in the very same tiny subdivision and had already set the site costs based on experience. And my block was consistent with their previous experience. I elected to pay extra though for some much deeper piers within about 9 metres of trees on the nature strip, as I was concerned about very long term effects of the growing trees (which was actually why my site was classified as "P" to begin with - not, I believe, explicitly because of the fill).

Okay, I have requested the level 1 certificate. Thank you.

If they can provide me one, where do I go from there?

Sorry very amateur here, glad these are forums like this!

Appreciate your response mr sausage!

You'd just make sure all the relevant parties have a copy - builder, the geotechnical consultant (as in who did your soil test) and the engineer responsible for your slab and footings.

I had Class M soil with "P" classification due to fill. Cost for screw piers was around $10K (270m2). If you have the correct compaction certificate then it goes on solid classification only as previously mentioned by a contributer.

With the level 1 compaction certificate, you shouldn't need piering but if you do, it will only be to depth of adequate bearing capacity, or for pools, trees or sewer etc.
Without level 1, your builder will have to pier down to natural soil with adequate bearing capacity. Effectively you will have a suspended slab on screw or concrete piers, much more costly.
Sometimes the builder has a cosy relationship with the land developer and they may already have a level 1 certificate and a ** trick is to give you a really bad soil test result (eg "p") then a shockingly high quote for footings and slab.
Then, voila they produce the level 1 certificate and reduce the footings and slab cost but still make plenty off you because they have played on your emotions.
I had 3 soil tests done before I engaged a builder and I had level 1 certificate.
I got 3 different soil test results . Then I shopped the worst soil result to builders until I found one prepared to fix my site costs.
It's a hell of process but better to know what you have got before getting a builder who just wants to screw you over.
Never go with the builders soil test, get at least 2 done by independents.
Cheers