Public sewer through back garden and doing an extension

ik1

Hi,

Hope someone can offer some advice.

I am purchasing a property and the searches has thrown up a potential issue with the public sewer running through the back garden. This is on all the properties on my side of the road that I can see on the map.

Servern Trent own this and as I am intending to extend at the rear I just want to be sure I wont face any issues. Having checked the severn trent website they do state "build-over" is possible on 300mm or less pipes and mine seems to be 150mm as indicated on the map.

The other problem is if the pipes need replacing Servern Trent state they will do it free now or if replacment is required in 10-15 years then I would need to pay for them?

I want to know is how expensive can this be if I have to pay for them? Having spoken to a family relative who is builder, he has stated that its not a problem and he has done this before on his own property and even replaced the pipes in the past and created a manhole where no existed before.

So has anyone been in a similar scenario and what was the outcome??

Many thanks

ik1

anyone????

SuzieSue

Might be best to post it on the In My Home DIY forum as I know there have been similar questions in the past.

Richard_Webster

Water company will want you to enter into a build over agreement that says that if all else fails and they need to get to their sewer they can demolish your extension with no compensation.

ik1

interesting...so it would be better if I try to move the sewer around my extension if possible, to avoid such issues. Thats if they let me and I can afford to do it!!

Richard_Webster wrote: »

Water company will want you to enter into a build over agreement that says that if all else fails and they need to get to their sewer they can demolish your extension with no compensation.

sonastin

Richard_Webster wrote: »

Water company will want you to enter into a build over agreement that says that if all else fails and they need to get to their sewer they can demolish your extension with no compensation.

There are plenty of techniques available for replacing pipes under structures and/or diverting the sewer without having to remove/disturb the original pipe. The water companies are also TERRIFIED of bad publicity so they really will pull out all the stops to make sure that you don't go complaining to the local paper about big bad Severn Trent pulling down your extension after they gave you permission to build it. This really is an ultimate-back-stop-less-than-one-in-a-million-chance catch-all to cover the absolute worst case scenario.

What you've got to watch out for is the standard of build required to build over the sewer. Our local building inspector has a reputation of being a little, shall we say, over-zealous. My neighbour has a sewer through his back garden and the building inspector's requirements for his foundation design, to ensure that the sewer wasn't damaged certainly looked like overkill to me. My neighbour did what the building inspector required because he wasn't able to check whether it was required by the building regulations or the water company but it certainly added cost to the price of his extension.

Richard_Webster

I've got a client who had a sewer running through his land that he wanted diverted and the Water Company insisted that he used their approved contractors who wanted double the stimated cost of the work deposited with them before they started.

andy.m_2

Listen to Richard, he really know's his onions.

I did

Davesnave

We built over a 150mm sewer, but in those days it was still in public ownership.

The build involved creating two very large bridges of reinforced concrete about 2' in section, one 14' long and the other 6'. These spanned the pipe at entry & exit at a depth of over 6'. Once the structure was up to around DPC, a reinforced floor was also added, so that the weight would be carried only by the outer walls.

We used our own structural engineer (a friend) and we did the building work ourselves, but had things been different, I think the project would have fallen at the first hurdle, due to costs. Of course, every job is different.

And yes, the Building Over Agreement gave the water board the right to enter the property and break up the floors to reach their sewer, but we felt that in the real world, it would surely be easier to re-route the pipe if replacement became necessary.

HTH

chappers

andy.m wrote: »

Listen to Richard, he really know's his onions.

I did

I agree.

The lack of the correct agreement not only leaves you open to potentially serious costs, but could make your property un-saleable.
A building control application in these circumstances will probably trigger the opening of a file with your water authority, which will require you to either apply for build over notice or prove that an application is not necessary. Without proof of either buliding control will not sign your extension off and when you come to sell two things will happen.
1. Searches will come back with an unresolved build over situation.
2. There will be no building regs approval for your extension.

You will almost certainly have to use STs contractor to divert the sewer and will have to have CCTV survays carried out before and after any build over.Assuming you get permission.
I would strongly advise that you follow the correct procedure on this one and find out all the facts and decide whether this extension is crucial in your decision as to whether to continue with the purchase of this property

Slinky

OP have any of the other properties extended over where you expect the sewer to be?

We have a build over with Anglian. Initially they didn't want us to go within a meter of the sewer, but in desperation we dug down and found it. It turned out the corner of our extension would be at a 45 degree angle to the sewer within six inches of it. Anglian came out and agreed we could build up to it but not over it, as long as precautions were taken. We had to have the base of the footings lower than the sewer, and put shuttering and gravel alongside the sewer before the concrete was poured. We took loads of photos so they could see what was done.

In theory Anglian could knock down the corner of the house if they needed to access the sewer. In practice there should be enough room to access it from our garden and the neighbour's garden.

Bit of a worry for a while as there would have been no point in having the extension without the extra meter.