Conversion of attached garage built over <160mm sewer in 2003.

[Turbonic]

Have read and read many similar threads but still have some questions.
Am wanting to convert an attached garage built in 2003. External wall is cavity brick/block and trench foundations.
In the middle of the existing garage door opening runs a foul sewer at about 1100mm depth, running front to back of the house.
The house is an end terrace and the sewer serves 4 houses
The floor of the garage is DPM and concrete slab.

The proposed wall and window to replace the garage door, will be built perpendicular to the sewer.

Where the garage door was inset by 1000mm the wall will be flush with the front of the house.
The wall will be cavity brick/ins/block, on trench foundations to invert + 150mm, and a bridging lintel

Questions

After doing a lot of reading, I am less clear concerning the need for a buildover agreement with Thames Water.

I had thought it could be self cert, did the questionnaire and am given full approval required.

This annoyed me, and I got to thinking. The substantial slab and existing foundations were approved in 2003.

Does the change in use of the garage therefore need a buildover agreement as the sewer was already built over in 2003.

To confirm there would need to be foundations dug, whish the sewer pipe will pass "through"

Any opinions/experiences?

Cheers, Nic

 

[freddiemercurystwin]

Your new foundation is being built across a (now) public sewer, so it needs a buildover. Are you getting Building Control Approval or doing it on the sly?

 

[Turbonic]

Have put in a building notice and paid the fee so trying to do it all by the book.
I had a good read of the self cert buildover requirements and thought all was well. This was until I did the TW questionnaire.

 

[Notch7]

Have put in a building notice and paid the fee so trying to do it all by the book.
I had a good read of the self cert buildover requirements and thought all was well. This was until I did the TW questionnaire.

is the garage over 6m long?

https://www.thameswater.co.uk/media-library/home/help/home-improvements/building-near-our-pipes/self-certified-build-over-agreement-specification.pdf

Does the change in use of the garage therefore need a buildover agreement as the sewer was already built over in 2003

well you are doing building work within 3m of a public sewer, so yes.

it wasn’t a public sewer in 2003

 

[Turbonic]

The garage was part converted previously, and the remainder of the garage (bit to be converted) is not 6m long. The run under the resulting house footprint, inclusive of the remaining garage would exceed 6m.

Maybe an important point to note is that we had a bedroom built above the garage on 2016ish and TW agreed after plans submitted. We built off existing foundations 1.7m deep trench.

The difference here for the actual garage conversion, was that from what I read I was sure I met the criteria for a self cert as wanted to avoid expense.

I had seen the pdf criteria before, however also another TW pdf a 12 page one which makes no mention of the 6m rule (will recheck though!)

 

[Turbonic]

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.thameswater.co.uk/media-library/home/developers/larger-scale-developments/sewers-and-wastewater/build-over-or-near-a-sewer/building-over-or-near-a-public-sewer.pdf&ved=2ahUKEwiBkp6zloL-AhU1hv0HHUdBAhYQFnoECBQQAQ&usg=AOvVaw1ATATrYAx4hDx6aTQlOB3S

This was the document I viewed which I don't think mentions the 6m thing. I do not disagree that the other one does though!

I see a conversation with TW in the near future