building on piles in WA

[Tano]

I am looking at a 17.3m wide block with a 150mm PVC sewer running 1.1m in from the rear boundary and 3.1m deep. From reading Watercorps asset protection guidelines it seems i need to be 1.5m away from sewer to build with no special foundations or 1m if i use special foundations.

Does anyone know the approx cost of building a single storey 3x2 b/t using piles? The perimeter of the rear of the dwelling will prob be 14m wide

 

[paulie]

Hi Tano,

I've always worked with a 2.5 metre set back from mains sewer lines for where building envelope can be without piling - and whilst your table may be correct, it does seem to be an industry standard within the spec home builders, so something to keep in mind when designing what you are looking to build.

 

[Tano]

Hi Tano,

I've always worked with a 2.5 metre set back from mains sewer lines for where building envelope can be without piling - and whilst your table may be correct, it does seem to be an industry standard within the spec home builders, so something to keep in mind when designing what you are looking to build.

Thanks Paulie
Im paying extra for this land due to the larger size block but if the land is unusable then i will walk.

Lot boundary setback (no sewer) = 1.5m (from r codes)
Lot boundary setback (this block with sewer) = 2.5m from sewer which is 1.1 from boundary = 2.5+1.1 = 3.6m

There is an extra (3.6-1.5) X 17.3 (width of lot) = 36m2 wasted space.

I could position the alfresco at the rear to take up some of this space but i am not sure what to do with the rest of the space. Have you seen anyone just make the alfresco just the width of the block in the sewer setback area and do these sell well?

 

[westminster]

I am looking at a 17.3m wide block with a 150mm PVC sewer running 1.1m in from the rear boundary and 3.1m deep. From reading Watercorps asset protection guidelines it seems i need to be 1.5m away from sewer to build with no special foundations or 1m if i use special foundations.

Does anyone know the approx cost of building a single storey 3x2 b/t using piles? The perimeter of the rear of the dwelling will prob be 14m wide

It cost me about $3-5000 for piling for building a 3 x 2 near a sewer line. It was actually on the neighbours side but as I wanted to go zero lot it required piling.

It wasn't excessive but did need to be taken into account.

 

[cd83]

Gday Tano,

My understanding is you can go to within 0.6m of sewer with piles. Most engineers will specify them spaced 2-2.5m along the wall adjacent the sewer so you shouldnt need too many. If you put the alfresco in the easement area as well you might only need a handful along a shorter length of building at that boundary.

Sounds like WM got a pretty good price. If you find a smaller contractor they might have an excavator with an auger than can do it cheap or (depending on where the site is) I know people who have done it themselves with a hand auger.

 

[bashworth]

I am looking at a 17.3m wide block with a 150mm PVC sewer running 1.1m in from the rear boundary and 3.1m deep. From reading Watercorps asset protection guidelines it seems i need to be 1.5m away from sewer to build with no special foundations or 1m if i use special foundations.

Does anyone know the approx cost of building a single storey 3x2 b/t using piles? The perimeter of the rear of the dwelling will prob be 14m wide

Its not just any piles, that's a much deeper sewer than you would find on a typical subdivision block, Those piles will need to be 3.4m deep.

For that depth you could well need bore casing so I would be talking to a piling company if you want a realistic idea of the cost

 

[Tano]

Thanks everyone. I will ask a few companies for more detailed information

 

[Jake D]

My understanding is you can go to within 0.6m of sewer with piles. Most engineers will specify them spaced 2-2.5m along the wall adjacent the sewer so you shouldnt need too many. If you put the alfresco in the easement area as well you might only need a handful along a shorter length of building at that boundary.

Sounds like WM got a pretty good price. If you find a smaller contractor they might have an excavator with an auger than can do it cheap or (depending on where the site is) I know people who have done it themselves with a hand auger.

0.6m is the minimum for the shallowest sewer. the red are in the picture Tano posted shows the minimum distance for other depths.

It is far more common for piles to be at 1500c/c max.

In the past I've heard of builder's allowing about $1000 per pile as a thumb-suck price.

14m, 1500c/c, $1000 /pile. I'd use $10k as an estimate and be happy if I got a cheaper quote than that.

(I've done pile design for two different engineering companies in Perth, I've never had to pay for or price any though.)

 

[cd83]

0.6m is the minimum for the shallowest sewer. the red are in the picture Tano posted shows the minimum distance for other depths.

It is far more common for piles to be at 1500c/c max.

In the past I've heard of builder's allowing about $1000 per pile as a thumb-suck price.

14m, 1500c/c, $1000 /pile. I'd use $10k as an estimate and be happy if I got a cheaper quote than that.

(I've done pile design for two different engineering companies in Perth, I've never had to pay for or price any though.)

Agree re the picture posted but have seen several jobs where they allow 0.6m above 3m sewer depth, provided it is a designed solution. If you are going to outlay cost of piling in this case I would apply for the min 600mm. The pile spacing does not need to be as close as 1.5m, so long as your capping beam (footing) is designed to span between the piles accordingly, its usually cheaper to make this slightly thicker/ a bit more reo and space the piles further apart. I work for a piling contractor and the price can be hugely variable depending on the size/overheads of the company, some wont even offload the equipment for less than 20k. As Jake says $1K per pile would be a pretty good price, probably one of of the smaller contractors might get down to the prices WM quoted.

 

[Tano]

Once the piles are installed , are you aware if there are any additional builder costs for running the slab over these piles? I am trying to work out the total build cost for this sewer problem.

 

[Jake D]

Once the piles are installed , are you aware if there are any additional builder costs for running the slab over these piles? I am trying to work out the total build cost for this sewer problem.

Usually a second layer of mesh in the strip footing.