Checking the drain - under conservatory!

[StatesOfMatter]

Hi all

Bought end of terrace house end of last year and it came with a conservatory that goes along entire back of house over 10 years old and pre-dates previous owners (I know Mumsnet is split on them but we like the idea of one). Has PC roof so in process of replacing it with insulated tiled roof.

Been looking over things to make sure nothing unforeseen happens and decided I needed to know about our drains (I know should have done this earlier. Hindsight is great!) - found out the conservatory was built over the main drain. Manhole access was kept (found by bringing up current worn Lino) which looks secure with screwfixed airtight cover and concrete in recess to match concrete flooring. This means drain runs under one wall of the conservatory to neighbour as part of shared drain system.

This throws up a few things - in particular are the foundations built in a way that means a heavier roof will not cause damage to the drain? I have flagged with company doing the roof so hopefully answer is the roof design will not put additional weight on that part of the wall.

Also as the entire drain is under the conservatory if we ever get a broken pipe that needs replacing the entire conservatory floor needs to come up. This wasn’t something identified during purchasing by anyone (and as FTB didn’t think to ask).

I am being overly anxious in wanting to check drains before proceeding with the conservatory work to make sure drains are fine before we spend lots of money on something we may need to bring down in a worst case scenario?

I am thinking of getting a CCTV survey done to check. Anyone had experience of these?

[pussycatinboots]

Ours is the same as yours, and the same age.

The additional weight of the replacement roof will be spread over the existing structure/foundation - not all at one point so it should be fine. It's still quite lightweight roof structure - not as heavy as a traditional roof with timbers and slate.

The fact that the "visible" bit (manhole cover) is done properly and hasn't just been left as original & tiled over (hidden) makes me think it's fine.

You could dig a trial hole against the wall where the drain runs to expose the foundations, and this would show if the drain had a lintel bridging over it to carry the weight of the structure above.

If the drain does ever fail, it is possible to "sleeve" it as a repair rather than digging the floor up.

If there had been an issue with the drains, surely it would have shown up by now?

For peace of mind, maybe do the CCTV survey?

[shiveringwiggles]

We're in the process of purchasing a house with this exact issue. Our surveyor has been made aware of it and is going into the house today. I'll update you with any feedback he gives!

[StatesOfMatter]

Update - the conservatory company have reassured me that it should be ok and have experience of dealing with this.

Thanks pussycat for sharing - comforting to know others have similar set ups. Thankful in a way that the owners who installed it seemed to have done the right thing and had decent builders!

I am going to have a CCTV survey done anyway as thinking about it we should have done one during purchase or soon after we moved in. That will give peace of mind anyway that all is well (nothing indicates there is an issue) especially as it would be hard for us to tell if there was a problem. And having a report is no bad thing before work is done and if we sell in the future we have a record it was (all being well) ok when we first moved in.

[Catsick36]

We've got the same but with a bricks and mortar and soon to be steel joist going over ours. It's in the kitchen. It's been fine, was like it when we moved in 9 years ago. We just looked into moving the drain. It was going to cost in excess of £15k which southern water wanted up front, the red tape hoops would have been a nightmare, they hold onto 20% of the money for a year after completion just in case.
It wasn't worth the palava or cost for us so it's staying where it is.

[marieg10]

Op...building and conservatory companies say all sorts. They may be correct but have you actually checked with the water company....even anonymously?

Our water company was a straight absolutely not without diverting it!! Fortunately didn't need to in the end

[StatesOfMatter]

Thankfully we are an end of terrace and at the end of the chain of the drains which connect so ours is a fully private drain so no permission needed to build over - now or retrospectively. (I have learnt too much about drains and permissions in the last week!)

CCTV survey done and all is good so one more thing crossed off the ‘know that about your house’ list.

[Witsend101]

If more than one house is connected to the drain then I thought that made it the responsibility of the waterboard? If you are at the end of the run it's still a shared drain. I'm not sure what you are hoping to achieve by getting the drains checked now?