Building an extension near a public sewer - has anyone any experience of this?

FAB

We are in the process of buying a house. One of the searches revealed a public sewer in the garden of the next door house, right next to the fence of the garden of the house we’re buying. We’re going to want to extend into our garden, small enough that we won’t need planning permission. We’ve been told we’ll need to get Thames Water to approve any work at the back of the house as it would be less than 3 metres from the public sewer. We’re told there would be a legal process and that the result will be a legal agreement which grants Thames Water access rights and other rights. Does anyone have experience of the process - how long it takes and the cost? Also should we be concerned that the rights given to Thames Water would put off potential buyers if/when we sell the house in the future? Thanks in advance for any information.

Doozergirl

Most of us have a public sewer in our back garden! Any shared drain is a public sewer, which is the responsibility of the water company, which in turn means that they have 'access and other rights' over the property.

There's no reason why it should put people off. It's a benefit to most people.

You're referring to a Build Over Agreement.
You've described it correctly, but that sounds far more scary than it is. It forms part of the Building Control process. It doesn't take long, and costs a few hundred pounds - the info will be in plain sight on TW's website.

Do you have the drainage search? The key should tell you the diameter of the pipe indicated by the colour of the line drawn. That's important as to what can be built nearby.

What does it say?

Slinky

We had a buildover agreement with Anglian when we extended our old home. We were initially refused permission to build within 3 meters, which would have meant revising our plans and ending up with a very odd shaped room. We dug down and located the sewer so we could assess the situation. It turned out this was running at a 45 degree angle to the corner of the proposed extension, and within a few inches of it. We contacted Anglian, they sent somebody out to look at what we were planning on doing, and they said that with extra deep footings so the load of the extension would be going below the pipe, and protection to their pipe by gravel and shuttering, they would be OK with what we planned to do. We also called the chap back on the day of the concrete pour so he saw the protective measures he wanted had been done, and was happy to sign off the job.


So yes it can be done, but be aware you may be turned down initially. With some detective work and making it easier for the water company to see what you plan to do to protect the sewer, may turn no into yes. But be aware if this sewer is on your neighbour's property, and your neighbour doesn't want you digging their land to find it, you may not be able to get as close to it as you'd like.


We recently sold the house, and made the EA tell any prospective purchasers all about the buildover agreement when they first viewed, in case this was an issue which would scare them off.


In terms of costs, they weren't huge, can't really remember now. £200-£300 perhaps, maybe less. It took months for a bill to arrive after we'd done the work, I did wonder if they'd never bill us, but about 9 months later they did. Make sure you keep all the paperwork as you'll need it if you sell later.

Cakeguts

I can never understand why people buy a house and then build a small extension? Doesn't it cost less overall to buy a house that has a big enough area downstairs to start with at least that way you won't lose the cost of the extension when you come to sell?



I can see that a small extension on the back of a house would be offputting to anyone who wanted to buy a house with the possibility of not having a weird shaped downstairs area or who would want to put on a decent sized extension without having to demolish someone else's small extension first.

Slinky

Cakeguts wrote: »

I can never understand why people buy a house and then build a small extension? Doesn't it cost less overall to buy a house that has a big enough area downstairs to start with at least that way you won't lose the cost of the extension when you come to sell?



I can see that a small extension on the back of a house would be offputting to anyone who wanted to buy a house with the possibility of not having a weird shaped downstairs area or who would want to put on a decent sized extension without having to demolish someone else's small extension first.

Location, location, location. Sometimes you can't find the ideal property in the location you want so you have to make do or adapt something that nearly ticks the box.


We intend a reasonable sized extension which will probably cost more than the value it adds, but we don't intend to move again so don't really care.

Doozergirl

Cakeguts wrote: »

I can never understand why people buy a house and then build a small extension? Doesn't it cost less overall to buy a house that has a big enough area downstairs to start with at least that way you won't lose the cost of the extension when you come to sell?



I can see that a small extension on the back of a house would be offputting to anyone who wanted to buy a house with the possibility of not having a weird shaped downstairs area or who would want to put on a decent sized extension without having to demolish someone else's small extension first.

Presumably you live in a cheap area where build cost per square metre is higher or similar to that of a house complete with the land it sits on. Where I am, it adds value and you get the cost of the build back, usually with some spare change to play with.

Buying a "proper house" with the relevant downstairs space means it comes with the associated upstairs space too, which also costs money. Fashion appears to dictate more living space these days and live-in kitchens.

Small is relative anyway.

Gaikokujin

FAB wrote: »

Also should we be concerned that the rights given to Thames Water would put off potential buyers if/when we sell the house in the future? Thanks in advance for any information.

[FONT=&quot]Technically they already have rights to access any drains: the responsibility for what were previously considered 'private' sewers (the connections from individual houses into the main 'public' sewer) was automatically transferred over to the various water companies across the UK in 2011. This means that if there are any issues such as leaks or broken pipes then it is up to them to deal with it and not the home owner.

As such they will want to ensure they have free access to the drains and access points (i.e. manholes) in the event of anything going wrong, so any building work over or nearby will need to be checked to make sure it doesn't affect this.

It will make absolutely no difference whatsoever when it comes to you selling the house in the future. If anything prospective buyers will insist on you providing proof of a build-over agreement so they don't get caught out themselves if anything goes wrong after the keys have been handed over.

[As an aside the same could also be said for you getting a certificate of lawful development to prove that any extension you build didn't require formal planning permission: costs about half the price of a standard domestic planning application but avoids any awkward questions at sale time over whether or not what you've built is legal].

From experience Thames water are one of the more helpful water companies to deal with when it comes to these kinds of things and are generally very amenable to proposals like this. There is actually a questionnaire on their website you can fill in and if the answers are acceptable you can get what's called a 'self-certification' agreement which won't cost you a penny. You'll need to make sure you have all available information you can about the existing drain and also what the building proposals around it will be so definitely talk this through with a builder to get a better idea before doing that.

If the proposals are too complicated for a self-certification - say for example like installing a new access point because you want to build over an existing manhole - that will most likely require a formal build over agreement with them which as I recall costs somewhere in the region of £300 and usually takes 2-3 weeks for them to approve.[/FONT]

BobQ

Have you established where your prospective sewer is located? Does it connect to the sewer you are concerned about. If it does you have a more complex situation as you might be building directly above a sewer.

JIL

Cakeguts wrote: »

I can never understand why people buy a house and then build a small extension? Doesn't it cost less overall to buy a house that has a big enough area downstairs to start with at least that way you won't lose the cost of the extension when you come to sell?



I can see that a small extension on the back of a house would be offputting to anyone who wanted to buy a house with the possibility of not having a weird shaped downstairs area or who would want to put on a decent sized extension without having to demolish someone else's small extension first.

I'm in the process of buying a house and we will be having a single story extension at the back. We dont intend to move again and we will fit the house around us.

Davesnave

Location, location, location, indeed.

In the 80s, we built directly over a 150mm sewer with an agreement. It wasn't easy because the sewer was over 2 metres down and at a difficult angle. Fortunately, we had family to call upon who could do the extra work, or we might have settled for something smaller.

Having this g/f extension made it possible for us to live in the house much longer than we'd have done otherwise, so it paid for itself. We consulted a large scale map of the town and concluded we'd never find anywhere affordable with such a large garden, so the extension was logical for us at a time when no one else in the road had extended.

Times change and areas increase or decrease in fashionability. Suddenly, in the late 90s, it seemed everyone in our road was extending.

Now, being single storey, ours is one of the smaller ones, but as Doozer says, size is relative.

Cakeguts

Doozergirl wrote: »

Presumably you live in a cheap area where build cost per square metre is higher or similar to that of a house complete with the land it sits on. Where I am, it adds value and you get the cost of the build back, usually with some spare change to play with.

Buying a "proper house" with the relevant downstairs space means it comes with the associated upstairs space too, which also costs money. Fashion appears to dictate more living space these days and live-in kitchens.

Small is relative anyway.

Where I live people don't want small extensions. The houses are mostly 1930s with the small kitchens so if someone is going to do an extension they will do a big one all across the back of the house to extend the size of the kitchen. I can't see anyone wanting to pay extra for a small extension on the back of the house because most people who want to extend want these big extensions to increase the size of the kitchen and so would have to demolish a small extension first in order to do their big one. The cost of demolishing something first would devalue the house quite a lot especially if it was in a popular area.