Dealing with a drain running through foundations....

[williamglossop]

Hi,

Please bear with me on this one as its really difficult to try and describe - i've tried to draw what I mean but I cant seem to get it right.

I am planning on building an extension to the rear of my house, off the back of the kitchen - there is a drainage pipe running parallel with the rear of the house that will pretty much run through the center of the floor/footings of the proposed extension.

The problem is the pipe is only about 300 mm down from the current floor level - whats more, the floor level outside the house, (i.e. above the pipe is the same as the kitchen, so when i've finished it needs to end up at the same height it is now, i.e. I cant raise the ground level.

Now, as I understand it, there are several ways to deal with a pipe running through concrete footings - but the pipe is higher than the footings. In my case the pipe will end up running above the footings and through a few of the layers of the sub floor. As I understand it, to build the floor I need at least 150 mm hardcore on top of the earth within the internal boundary of the footings, 20 to 50 mm sand, DPM, 100 mm concrete slab, 70 to 80 mm insulation and then 65 mm screed - I would need this screed to finish level with the existing kitchen floor. Due to the fall on the drainage pipe (from right to left across the plot) I suspect it may pass through 2 or more of these floor levels.

Is there a solution to this problem?

I don't know if i've explained that clearly enough or not - probably not

 

[noseall]

The pipe is ok to run through the sub-floor. In fact your job is more simplified because it sounds like they will be positioned in the hard core layer.

Just lintel over the pipe at each end and allow say 50mm clearance above the pipe and similar for the sides.

We had a nightmare job a few years back whereby the already shallow (existing) drains ran partially through the insulation layers. It was a pig to cut around the pipes!

 

[nickjb]

Is this a shared drain? Is it used by the neighbours? If so you will need to contact the water company who will want to inspect the works and charge you for the privilege. If you don't you risk them demanding it be pulled down at some later date. If it is just your drain then carry on, shouldn't be too tricky. Might be worth replacing the pipe if it is old to avoid issues later. I replaced the old clay pipe I built over with plastic. Every single joint in the clay had a crack and a small leak.

 

[tony1851]

If it's only 300 below g.l., it is probably at the top of the run and could well be OP's own drain?
Yes, replace in one length of plastic while it's exposed.

 

[williamglossop]

despite the pipe only being 300 mm deep, it is shared with several houses further up the terrace. The road slopes downhill and the pipe runs parallel with the ground level so its a similar depth below ground all the way along the back of the terraces.

How much is the likely cost of a build over agreement? How long do they typically take? I presume the BCO will advise me for certain if one is required, but just trying to get an idea of timescales and costs

Does the pipe not need to be protected as it runs through the layers of the floor? Also

 

[noseall]

Does the pipe not need to be protected as it runs through the layers of the floor? Also

It will be protected by the floor slab.

How much is the likely cost of a build over agreement? I presume the BCO will advise me for certain if one is required

Your designer or architect will advise about permissions etc within his design criteria.

If you are tackling this job blind, i.e. without professional guidance and relying upon a building notice then you as the homeowner will be responsible for all permissions etc. B.C. are likely to give you a cursory nod in the direction of the water company, though they are not obligated to hold your hand or babysit you through an extension.

 

[excited]

If you are tackling this job blind, i.e. without professional guidance and relying upon a building notice then you as the homeowner will be responsible for all permissions etc. B.C. are likely to give you a cursory nod in the direction of the water company, though they are not obligated to hold your hand or babysit you through an extension.

So if he was to do it under a Full Plans to BCO then they would seek all permissions ?

 

[freddiemercurystwin]

In my experience BC will take a view on it, if it looks like there could be some risk he will get you to do a Build Over, otherwise he may be happy for you to do it without. This sounds pretty straightforward and I would expect them to be fine with bridging over the pipe. But none of us are your BCO.

I would get your BCO out and see what he wants you to do.

 

[maltaron]

"It is shared with several houses" and as such comes under the local water authority, (whether they know it or not is a mute point) and they can be right b******s. As has been pointed out earlier in this thread you could have major problems if you ignore this. This is wear PD falls down, if PP was required it would be a condition of the PP to contact the water authority to discharge this condition.

 

[mandm65]

would different rules apply if your house was the first house on shared drain?

 

[maltaron]

I think if you are the first house it is classed as a private drain until the point where the first neighbour joins.

 

[mandm65]

I think if you are the first house it is classed as a private drain until the point where the first neighbour joins.

Intresting, so does this imply that if you have a blockage in the drain then you cannnot call the utility compnay?

 

[freddiemercurystwin]

Yes, only drains that are shared by more than one property and are within 3m of any development are the Waterboards responsibility (technically needs a Build Over).

Any drain that only serves your house is your responsibility (does not need a Build Over but still needs to be done properly and to the satisfaction of the BCO).

The responsibilities are very clear.

 

[mandm65]

Thanks for the clarification.