All Topics / Help Needed! / Sewerage pipes …help please. Want to build a granny flat

Viewing 17 posts - 1 through 17 (of 17 total)
  • Woody1986
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    @woody1986
    Join Date: 2010
    Post Count: 57

    Hi guys. I just purchased a property with sewerage running from front to back fence in the back yard and I purchased it with the view of building a granny flat. It is in the black town council region. I am 1 week from exchanging and wanted to know if this could potentially stop me from building a granny flat there or if worst comes to worst could I encase the pipe. Does anyone have any advice on what info I should find out and where to minimize problems in the future. Thanks

    Profile photo of Scott No MatesScott No Mates
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    @scott-no-mates
    Join Date: 2005
    Post Count: 3,856

    You will need to determine if this is the Board’s sewer or your drainage. There should be few issues if it is your service. what does sewer diagram indicate? Where is your boundary trap?

    Woody1986
    Participant
    @woody1986
    Join Date: 2010
    Post Count: 57

    Thanks for your reply. I have no idea really when it comes to drainage It actually runs across from side fence to side fence instead of front to back. My main concern is the council saying that I can’t build a granny flat once I buy them property which would defeat the purpose of buying. What are the things I should tick off before I pay the cooling off deposit. I h e sent the diagram through to a builder and he seemed to say it was alright although he has mainly done bigger developments and not granny flat so I just wanted to try and get a much advice as possible an insight into what could go wrong. Thanks again for ur help. It I much appreciated

    Woody1986
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    @woody1986
    Join Date: 2010
    Post Count: 57

    Sorry but I am unsure what a boundary trap is aswell?

    Profile photo of mattstamattsta
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    @mattsta
    Join Date: 2011
    Post Count: 604

    same. what is a boundary trap?

    Profile photo of grantos_champosgrantos_champos
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    @grantos_champos
    Join Date: 2009
    Post Count: 106

    You should have jumped onto Dial Before You Dig first and put in a request. This service is free and will highlight where the sewer (and any other services in and around your property) runs. This is a great quick tool for looking at what you can do with a site. Eg, on a development site you can quickly see if the sewer is on the other side of the road or not. If it is then you may have to thrust bore across to it or put some traffic control in place and trench across.

    Whether or not it will stop you building a granny flat depends on a few things:

    – where you want to locate the GF
    – how big your block is
    – how big the existing building envelope is
    – ingress/egress of the GF

    If the main sewer line runs through your yard then it will have an easement over it and will limit (but not make it impossible) your chances of building a GF. It should run along your boundary at a 1m offset and the easement width will probably vary depending on the water boards specifications. FYI you cannot build within this easement.

    RE: encasing the pipe – some good building design should eliminate this need. Digging down 1-6m is a big, big job, especially in suburbia!

    A boundary trap is a U shape in your sewer that is located at the boundary. It stops any bad gases from the main sewer creeping up your pipes, similar to what is in your kitchen sink. Look for a pipe rising up out of the ground with a little concrete surround somewhere along your boundary, thats the BT.

    Profile photo of BMWBMW
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    @bmw
    Join Date: 2012
    Post Count: 25

    If the council is saying you can't build, then you most likely wont be able too.
    if the sewer pipe is your internal line to the main council line, you may be able to move this at a cost.
    if it is the council line, you have bucleys chance. 
    The drainage diagram should indicate the location of these, but you can also check the location of the council line by looking for the manholes and join the dots between the two (they always run in straight lines).  the council will have a digital map of the location of it's mains but they are not always correct, and the advice you recieved from the council may have been relying on this.
    I'd be ringing the council and asking what restrictions there are about building near sewer lines and asking for a map of the property with the sewer services.

    Woody1986
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    @woody1986
    Join Date: 2010
    Post Count: 57

    Thanks heaps for your information guys. . Really helpful…. I havnt cooled off yet so I will further investigate with  your information provided. ..Thanks again

    Profile photo of BrazenBrazen
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    @brazen
    Join Date: 2010
    Post Count: 47
    James Wood wrote:
    Hi guys. I just purchased a property with sewerage running from front to back fence in the back yard and I purchased it with the view of building a granny flat. It is in the black town council region. I am 1 week from exchanging and wanted to know if this could potentially stop me from building a granny flat there or if worst comes to worst could I encase the pipe. Does anyone have any advice on what info I should find out and where to minimize problems in the future. Thanks

    Hi James,

    You can encase the Sewer Mains' Pipe if you're forced to, but thats only if it's lying right under where you want to build. There are alternative ways to avoid encasement and it all depends on the distance you are (laterally) from it and the depth of the Sewer Mains' itself. Here's a post that explains the formula used by Sydney Water to decide how much it's going to cost you to mitigate the asset:
    http://www.grannyflatapprovals.com.au/news/granny-flat-sewer-help/

    Serge.

    Brazen | Granny Flat Approvals Sydney
    http://www.grannyflatapprovals.com.au
    Email Me | Phone Me

    Granny Flat Approvals Guru

    Profile photo of KeyStrategiesKeyStrategies
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    @keystrategies
    Join Date: 2011
    Post Count: 155
    James Wood wrote:
    Hi guys. I just purchased a property with sewerage running from front to back fence in the back yard and I purchased it with the view of building a granny flat. It is in the black town council region. I am 1 week from exchanging and wanted to know if this could potentially stop me from building a granny flat there or if worst comes to worst could I encase the pipe. Does anyone have any advice on what info I should find out and where to minimize problems in the future. Thanks

    So james how did you go? The question I would have asked is where exactly was the sewer line – running from front to back? if its was along the side boundary and out of the way it may not have been an issue .

    Would be interested to hear  the outcome

    Profile photo of Brian PobjeBrian Pobje
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    @brian-pobje
    Join Date: 2012
    Post Count: 21

    Hi James,

    Need to know where it runs across the block
    is it at the front, middle or back of the block, will the granny flat be built over the easement.?

    Profile photo of NHGNHG
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    @nhg
    Join Date: 2010
    Post Count: 198
    Scott No Mates wrote:
    You will need to determine if this is the Board's sewer or your drainage. There should be few issues if it is your service. what does sewer diagram indicate? Where is your boundary trap?

    Hey, have the same issue.

    If it is my drainage and not the boards, and runs directly down the middle of the backyard front to back. Will I need to concrete encase it? Doesn't look like there will an impact from the zone of influence, however it runs directly underneath the building itself.

    Profile photo of Brian PobjeBrian Pobje
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    @brian-pobje
    Join Date: 2012
    Post Count: 21

    Having been in real estate for over 16 years, I have found that if the sewer runs under a property that it severely decreases the number of people that are interested in buying that property, solicitors and builders will also add to the buyers uncertainty of such a purchase.
    People get worried about the what if questions, what if it bursts, what if the council need access?

    Profile photo of NooobNooob
    Member
    @nooob
    Join Date: 2012
    Post Count: 34

    Just from the engineering point of view:
    If your structure is going to sit on the sewer line you will require a piling mechanism to pass the load of your building to a layer deeper than the sewer.

    As a rough figure for a single level building you will require screw piles every 1.5m (on top of the sewer line only) and they will be roughly 3m long base on the ground condition.
    so say if the length of your granny house is 8m on top of sewer, you will require 6 screw pile at ~$600 each.

    This is just in case there was requirement to repair the sewer line, your building will stay safe.
    Council will look at the access to make sure in case of repair required, there will be enough access.

    Profile photo of sarahddsarahdd
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    @sarahdd
    Join Date: 2012
    Post Count: 1

    Hi James and anyone else dealing with this issue.

    I've had development approval for a studio/guest "house" at the rear of my property. It will only measure 6m wide by 4m deep – and constructed of concrete slab, brick walls, metal roof.

    I have had the same issue – I have a sewer pipe running across the back from left to righ (side boundary to side boundary). It is set in a metre from the rear boundary.  On top of this there is a tall vent shaft in the corner which meant I had to redesign the granny flat to sit 1m away from the vent shaft.The sewer pipe issue has added an extra year to the process. (Although don't let that scare you – it probably should have only been 3 months max as I kept procrastinating about whether this was worth my while.)

    I have found every professional incredibly unhelpful, yet very expensive. Everyone seems to 'pass the buck' onto the next professional with conditions and waivers and 'subject tos' and what not – so you end up on this seemingly never ending adventure never quite knowing for sure if it's going to get approved or not whilst spending more and more money along the way.

    Anyway, I've finally had approval from Sydney Water and have proceeded to get quotes to get on with the job. Sydney Water actually didn't seem to care too much as long as the pipe is being encased. Also, their rules are that buildings need to be 2m from vent shaft – but they have allowed me to keep it only 1m as they have access from another side anyway.

    So I thought I would let you know, the actual encasement and piering work will add at least 20K to the cost of the building.  I figure once it is done, I won't have to worry about it again. But, if we find that during construction the buildings either side (neighbours laundry, other neighbours fence and patio) – need shoring/propping up it could add more to the cost.

    I am wondering –  if I change the construction type to an elevated lightweight structure, timber floor, elevated 20cm off the ground, sitting on piers going around the perimeter of the building…..wouldn't this mean we don't have to encase the sewer? As there is no weight bearing down on the ground over the sewer?

    If this is the case – I am tempted to change the construction type at the last minute to try and save costs. If anyone knows about avoiding sewer encasement could you let me know?

    Regards,
    Sarah.

    Profile photo of BrazenBrazen
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    @brazen
    Join Date: 2010
    Post Count: 47
    sarahdd wrote:

    I am wondering –  if I change the construction type to an elevated lightweight structure, timber floor, elevated 20cm off the ground, sitting on piers going around the perimeter of the building…..wouldn't this mean we don't have to encase the sewer? As there is no weight bearing down on the ground over the sewer?

    If this is the case – I am tempted to change the construction type at the last minute to try and save costs. If anyone knows about avoiding sewer encasement could you let me know?

    Regards,

    Sarah.

    Hi again Sarah,

    The answer is no. Regardless of whether you're building on piers or a slab, Sydney Water's rules are the same. Id get a multitude of quotes for encasement. $20k seems pretty steep to me, It's usually around $1,000 per square meter from my experience.

    Brazen.

    Brazen | Granny Flat Approvals Sydney
    http://www.grannyflatapprovals.com.au
    Email Me | Phone Me

    Granny Flat Approvals Guru

    Profile photo of graham_williamsgraham_williams
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    @graham_williams
    Join Date: 2013
    Post Count: 1

    Building over a sewer can be complicated, but once all the details are figured out, hopefully the actual building goes smoothly.

    A Class Concrete and Landscape

    http://www.aclassnsw.com/au/

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