Building over sewer pipe in Queensland

Mofflepop · Jan 26, 2024 1:24 pm

Hi all,

*Yet to get an answer from my building broker about this (must be very busy!)* but we are looking at the site positioning options for our yet-to-be-selected house plan, noting that there is a council sewer pipe and maintenance point running right through the middle of our block (maintenance point is at the fence line). We have a very long block, so technically we could avoid building over it and build either in front or behind the sewer, but this would restrict our floor plan options and we want a certain size house.
So, we are trying to get an idea of the costs involved with building a ‘bridge’ over the sewer and have been told by new build sales people an estimate that ranges between $3000 and $40,000 to build a house over a sewer. We don’t understand why some say it’s not that costly, and others say it is $40,000.
We also don’t know if this is something that can only be determined after getting an inspection of the sewer to find out its depth in the soil and the state of the pipe, etc.
Lastly, we are not sure if we can get the sewer inspection done while the tenant is still living in the property (we are planning a KDRB once their lease ends).
Oh - and one more thing I just thought of - has anyone had issues putting their house at the back of their large block in Brisbane City Council? Or has council said it has to be placed in line with neighbouring houses (our current front set back is about 6 metres). Thanks ☺️

obiwon · Jan 29, 2024 1:13 pm

BOS isnt a big deal. Generally its just deeper bored piers down to something solid on each side of the sewer. There will also be some slab thickening as well.

As you pointed out, it will depend on the depth of the sewer but they are normally all in similar depth locations but it depends on the soil conditions under your slab - the depth of adequate founding materials to bore the piers to (founding depth).

Other than that there will be surveying fees to locate and mark the sewer line length/depth (location) so contractors dont damage it.

The setbacks are all determined by the local council and the overlays that apply to the area (based on the location of your site).

You can engage a private certifier for "pre-lodgement" building advice, its normally not a big cost, and they will detail all the things that apply to your site. The pre-lodgement generally just entails them searching overlays.

I haven't looked them up in a while but they used to be online, through the councils website - the overlay searches that is. You input your site address then they show you the overlay maps, you print them all out and read through them to get an idea of what will apply in the granting of building approval.

I hope this helps you Mofflepop

Mofflepop · Jan 29, 2024 2:38 pm

obiwon

BOS isnt a big deal. Generally its just deeper bored piers down to something solid on each side of the sewer. There will also be some slab thickening as well.

As you pointed out, it will depend on the depth of the sewer but they are normally all in similar depth locations but it depends on the soil conditions under your slab - the depth of adequate founding materials to bore the piers to (founding depth).

Other than that there will be surveying fees to locate and mark the sewer line length/depth (location) so contractors dont damage it.

The setbacks are all determined by the local council and the overlays that apply to the area (based on the location of your site).

You can engage a private certifier for "pre-lodgement" building advice, its normally not a big cost, and they will detail all the things that apply to your site. The pre-lodgement generally just entails them searching overlays.

I haven't looked them up in a while but they used to be online, through the councils website - the overlay searches that is. You input your site address then they show you the overlay maps, you print them all out and read through them to get an idea of what will apply in the granting of building approval.

I hope this helps you Mofflepop

Hi Obiwon

Thanks for that. Good to hear it isn't such a big deal, I just wish I knew why to-date I've had such differing advice about how much it costs! Our soil is kinda sandy (not ridiculously so) - yet to get soil test (and surveys) done.

I've definitely looked at the BCC website regarding overlays, set backs and all of that information before. I am supposing I could ask for a relaxation on the 6 metres it states (from memory). I have a building broker so they should hopefully guide us with pre-lodgement building advice, etc.

We'll get the sewer CCTV inspection done soon

obiwon · Jan 29, 2024 2:55 pm

I think you are getting different numbers because they all just based them on "other jobs" even though each job is unique.

Often, with builders, unless you're speaking to the actual builder or to an estimator, and if it's a big building company you're dealing with - almost no one else (other than estimators) and especially admin staff, will have any idea of costs nor how it actually goes together onsite. Most admins in big builders have little building knowledge or experience, they just know the company process and how to move people through them.

The actual costs will completely depend on where your house is situated in relation to the sewer.

Salespeople always have a "book of indicative costs" they keep from elements priced on previous jobs. They always like knowing what cost ranges to tell people so they can give "an answer" rather than "no answer" and lose face.

So once out have your soil test done then locate the sewer you'll know how deep your piers will be, how many needed and can cost it up.

If you have the space on your site, and you need a few piers, timber piles can be a good option as well as concrete bored piers.

Best wishes,

The force is strong with you and your home journey :-)

Obiwon