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.