Best course of action? FTB, future extension [UPDATED WITH DIAGRAM]

OSCO

Hello

We're first time buyers and have just put an offer in on a house.

The house sits on a decent corner plot so on the face of it has great scope for an extension.

Someone did get in before us on the sale but later pulled out. The estate agent has told us that they were looking to add a sizable extension to the property but under estimated the costs. This could be true, but clearly I want to be 100% sure everything is okay with the property so we'll be having a full building survey.

Whilst we don't necessarily want to build an extension right away, a big draw of the property is the plot size and scope for extending in the future.

However, I have noticed that ~1-2m behind the property are two inspection covers and to the side garden is a manhole cover.

I've tried to quickly put something together in paint to illustrate a bit better (don't laugh too hard):

EDIT - CAN'T POST PIC BECAUSE I'M A NEW USER. URL IS imageupload . co . uk /images/2017/09/19/house.gi f WITHOUT THE SPACES; IF SOMEONE CAN BE KIND ENOUGH TO REMOVE THEM AND POST IT UP!? :beer:

I've looked online for guidance from the sewage company (Welsh Water) and it indicates that building over their covers is not allowed and instead they have to be relocated.

We phoned the sewage company up and they cannot provide info/plans of the sewage's in/around the property - apparently it's a bit hit and miss on what is shown. I'm guessing it used to be private to the property but they took ownership in 2011 when they were all transferred.

From looking at the layout I'd imagine there's a main pipe running from behind the properties and the inspection covers at the back are the junction where our pipes join (why would there be two though?) and therefore if we just extended to the back it should be easy enough to move them to the side of the extension?

I know the only way to be sure is from looking in them.

I'm unsure on the best path forward, though.

Do I contact a decent builder and see if the sellers would allow us onto the property with them to open it and look at the feasibility?

Is this something that would/could be covered during the building survey?

Any advice would be great!

Thanks

armchaireconomist

I thought you could build over the manhole covers on the condition you don't block access? Half my street has built over them and put access hatches in the floor.

LandyAndy

http://imageupload.co.uk/images/2017/09/19/house.gif

OSCO

armchaireconomist wrote: »

I thought you could build over the manhole covers on the condition you don't block access? Half my street has built over them and put access hatches in the floor.

I'm not sure if it depends on the sewage company. Unless I've misunderstood, the criteria for approval from Welsh Water state that you can't build over their covers and instead they need to be moved.

Doozergirl

armchaireconomist wrote: »

I thought you could build over the manhole covers on the condition you don't block access? Half my street has built over them and put access hatches in the floor.

Absolutely not allowed!

May well have been done in the past but the potential consequences are pretty disgusting.

OSCO

OSCO wrote: »

I'm not sure if it depends on the sewage company. Unless I've misunderstood, the criteria for approval from Welsh Water state that you can't build over their covers and instead they need to be moved.

... The extensions may also have been done pre-2011, and therefore were private and not owned by sewage company?

Doozergirl

It will be pretty obvious where everything is coming and going from if you open the inspection chambers. You don't need a builder to do that. However, a build over agreement will require CCTV footage of the existing drains and it's a pretty prudent thing to do when buying a house, so that would be your better option, especially if you're not prepared to open covers yourself and rely on your own judgement.

It's hard to re-route shared sewers, as you introduce angles, but relatively simple to move your inspection chambers so that waste coming from your house connects onto the main sewer outside of your extension, with new inspection chambers.

Build over agreement is still required.

More important is advice from an architect. Corner plots do have opportunity but they can be restricted by having two building lines from two streets to contend with.

Also, it makes financial sense to wrap that extension around, not build two separate ones. You're creating exactly the same length of new external walls but restricting size of the extension by having an internal corner.

OSCO

Doozergirl wrote: »

It will be pretty obvious where everything is coming and going from if you open the inspection chambers. You don't need a builder to do that. However, a build over agreement will require CCTV footage of the existing drains and it's a pretty prudent thing to do when buying a house, so that would be your better option, especially if you're not prepared to open covers yourself and rely on your own judgement.

It's hard to re-route shared sewers, as you introduce angles, but relatively simple to move your inspection chambers so that waste coming from your house connects onto the main sewer outside of your extension, with new inspection chambers.

Build over agreement is still required.

More important is advice from an architect. Corner plots do have opportunity but they can be restricted by having two building lines from two streets to contend with.

Also, it makes financial sense to wrap that extension around, not build two separate ones. You're creating exactly the same length of new external walls but restricting size of the extension by having an internal corner.

Thanks, makes sense

Maybe another call to the sewage people then - to see if they can inspect for us?

Yes, if we were extending both ways we would wrap around - or maybe just go out one way or the other depending on what is feasible

ProDave

Just go for another viewing and lift the covers to see which direction(s) pipes exit from them. Wherever they exit they should run in a straight line. If you can't do it, get a friend or builder or probably a plumber to go with you with the pair of handles needed to lift a drain cover.

My gut feeling is the back extension could be very expensive to relocate those drains and inspection chambers. Can you live without a rear extension.

As long as the right hand chamber on your drawing does not have a pipe branching and running alongside the house you are probably okay for a side extension.

Another thought is cables. If the builder / plumber that accompanies you brings a CAT scanner he can check for those at the same time.

UKTelecom

Kudos on the image you provided btw. Nicely presented.

OSCO

UPDATE

We had the drain survey carried out.

No issues with the drains.

They provided the following plan. I was expecting it to be a bit more informative TBH, but may just be me. I plan to call them on Monday to confirm how the plan relates to what you see at the property.

The plan they've provided:



This is the opposite way up to my previous crude diagram of the property:



My plan is correct as to where the covers are in relation to the property, so on their plan MH3 is really to the left and diagonal to MH2. I'm assuming that MH3 is the junction where the three pipes meet, but unsure why they wouldn't have just put it in the correct place in the diagram...

As far as I can tell, the pipe with MH2 shouldn't be an issue with an extension as MH2 could be moved closer to MH1 with the pipes from the house joining where the new cover would be?

The pipe with the MH3 and RWG1 is a bit more confusing to me and potentially an issue? I am not sure what RWG1 is and where it comes from. The garage is in that direction, but if it came from a garage I would have thought it would be in orange being private not shared :huh: unless it comes from other houses.

We'll be phoning them next week to ask, but thought I'd post on here to follow up as you're all usually helpful :beer: so any thoughts welcome!

Thanks