Addtional Slab costs betweeen soils H and P

R

redsquash

If a concrete slab is to be built on flat land ,with a soil classification of P as distinct from H,
what estimate as a percentage would additional expected costs might there be .
Can a dollar estimate be put on this with the information below

I have been told an additional cost might be $1200 between H and M

Some additional details.
270 sq m single story house
external and internal piers
existing Fill,,highly reactive soil, services
silty clay foundation layer and piers 450mm dia

I would like to have this information before speaking to some professionals,since I dont know what I wrote !

How bad is P . What problems might occur in the future
 
P just means thst you may need some peiring. Whoever is building your house will be the one to speak to because it varies between builders.

I know my H class slab cost me $6000 with Alliance, I was told the same would cost $8-10k with coral homes and 12k with tamawood.
 
This was the exact same question that I wanted to ask.

Our geotech engineer classed our soil as Class P, extremely reactive.

Apparently it would cost us a lot more to build on this type of soil?
 
If you have a 'P' classification it is normally due to the presence of fill material on the block. Generally it will also be noted as being a s,m,h,e slab.

Basically if it has a 'P' classification it is calling for piering to your slab, however, most developers can supply (and SHOULD) supply a compaction report or compaction certificate showing that it is 'controlled fill'.

Your builder should then be able to negate the need for piering.

As a rule of thumb slabs should cost the following...

S - included in your base price
M - $9 per m2 additional
H - $19 per m2 additional
E - depends on the builder and the severity of the clay/fill and water table location

Most sites nowadays are M or H as the developers are adding a lot of fill to make the blocks flatter and therefore more appealing. I would always allow for M class when costing up with your respective building companies.

Hope this helps....
 
anthonykirby said:
If you have a 'P' classification it is normally due to the presence of fill material on the block. Generally it will also be noted as being a s,m,h,e slab.

Basically if it has a 'P' classification it is calling for piering to your slab, however, most developers can supply (and SHOULD) supply a compaction report or compaction certificate showing that it is 'controlled fill'.

Your builder should then be able to negate the need for piering.

As a rule of thumb slabs should cost the following...

S - included in your base price
M - $9 per m2 additional
H - $19 per m2 additional
E - depends on the builder and the severity of the clay/fill and water table location

Most sites nowadays are M or H as the developers are adding a lot of fill to make the blocks flatter and therefore more appealing. I would always allow for M class when costing up with your respective building companies.

Hope this helps....
Click to expand...
Hi Anthony,
Great information.
site classification is P
There is a Prelimnary site classification report and a certifivate of controlled filling dated 1 week later.

Does this imply a futher report will be forth coming?
Contract states an M slab
 
If it is a preliminary report - it is generally because it is subject to change based on compaction reports etc.

If you have signed the contract - and it is a fixed price (which it should be at contract stage) then if they have charged you for an M class slab only - they should not be charging you for piers...

If they have charged you for piers - and you can supply a satisfactory compaction report on the block, then you should be able to do a 'post contract variation' to get the piers credited to you - as they should not be necessary.

Hope this helps.
 
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