Conservatory wall crossing a drain pipe

[Tim Watts]

Hi,

Just wanted to run a quick common sense check here:

Having a conservatory added round the back. This sits over a single continuous length of 110mm plastic soil pipe. There are two conservatory walls over the pipe - east and west sides.

East side is 2ft below ground surface and will have a lintel over it for good measure.

West side turnes out to be more complicated as the bit that is over the pipe is where the wall changes direction through 45 degrees so it's not easy to see how to add a lintle.

So the builder said he has dug down to just below the pipe base level on both sides. Assuming the pipe is surrounded by 10mm gravel[1], I cannot see who this is likely to be a problem. The loads are small (600mm dwarf wall, uPVC frame and glass) and as long as there is some gravel and the concrete strip bears onto ground under the pipe I can't see any significant forces acting on the pipe (which is within a foot of a chamber on both the east and west crossings).

Seem reasonable?

[1] I have yet to inspect this myself as this is the one day I had to be actually at work.

[Tim Watts]

On Wednesday 31 July 2013 18:48 Phil L wrote in uk.d-i-y:

Yes - I guess that is the most succinct way of putting it.

No - it's unfortunate that I was not there to see it in person (see below).

I know enough that it flagged up as a point of concern though.

I was considering the same, if I were the one doing the work. If I'd been around, I would have supervised this a bit more closely and pointed him at the bit of mesh I have spare behind the shed.

The builder is a subbie of the bloke who I have a contract with so I'll ring him tonight before we get too far that remediation is a problem.

Thanks for the comments...

Once again, goes to show that outsourcing a job is no excuse to not be vigilent....

Cheers,

Tim

[Andrew Mawson]

In practical terms there probably wont be a problem, just use common sense and bridge it to spread the load, but if a building inspector is involved he may even want an engineers report :(

AWEM

[Tim Watts]

On Wednesday 31 July 2013 19:01 Andrew Mawson wrote in uk.d-i-y:

The BCO has said (prior to work starting) that a conservatory is of no interest to him -

As I said to Phil, if I'd been around today[1] I would have had enough involvement to achieve a sensible solution. I do have a large pile of paving slabs too!

[1] This was supposed to be done yesterday but were were rained out and today, the builder had a slight mishap that involved me taking down to the local doctors - so whilst I had planned to be around for all the bits that mattered, I wasn't.

The pipe crosses just under the edge of a doorway -

I think the key thing I have concluded is whether concrete has been laid directly onto the pipe (bad) or whether he did what I said and put a buffer layer of gravel (suitable contained) bewteen concrete and pipe.

Cheers!

Tim

[Tim Watts]

On Wednesday 31 July 2013 19:07 Tim Watts wrote in uk.d-i-y:

Oh - and just for the sake of completeness - there is an element of DIY in this task - I'll be laying in the electrics and UFH.

[Tim Watts]

On Wednesday 31 July 2013 18:48 Phil L wrote in uk.d-i-y:

Just got home - here are some pics:

1st pic shows pipe projected correctly.

2nd pic - yes the pipe runs right through the corner of the turn in the wall (run is "vertical" through the photo via the middl eof the round chamber lid). Gawd knows what's going on down there. Allegedly there are photos.

3rd - footings stepped to follow ground

4th - I would have stepped those footings down another course - those are going to be visible above the ground level. Yes can be disguised, but why not step then down one more level.

This is why I hate employing people[1] - he's a nice guy but leave a job unattended for 6 hours and you just end up with a pile of problems!

[1] Well, I get on OK with trade specialists like tilers and plasterers, but then again I've seldom left anyone on their own before.

I'll speak to the main contractor...

Am I being too fussy?

[Tim Watts]

On Wednesday 31 July 2013 18:48 Phil L wrote in uk.d-i-y:

Just out of interest - what can happen? I'm presuming that there's a risk of slight settlement of the structure distoring the pipe if it's in direct contact?

[Tim Watts]

On Wednesday 31 July 2013 19:52 Phil L wrote in uk.d-i-y:

Good point!

Thanks - I'm halting work until I'm happy.

[Tim Watts]

On Wednesday 31 July 2013 19:56 Phil L wrote in uk.d-i-y:

Well, the main contractor is coming first thing tomorrow.

I'm a little uneasy about his opinion as he reckons it's "OK to lay concrete on plastic".

I did point out the concrete is within 6" of the chamber joint and the chamber is effecitvely an immovable object as it is bedded onto it's own concrete - meaning any movement will stress the joint.

Do you reckon I should halt work and call the BCO over?

Gawd...

[Tim Watts]

Ah - found it...

Part H page 49

Basically (can't copy n paste for some reason):

100mm gravel around pipe (check) and pipe is

[Tim Watts]

On Wednesday 31 July 2013 19:45 Tim Watts wrote in uk.d-i-y:

Builder's off today after damaging his eye (so to all those who angle grind without goggles, let that be a warning!).

Main contractor came round. I gave him 2 pages printed from Part H Building Regs and he did not argue. He said we'll check the photos that were apparantly taken, and if I'm not happy, he'll dig an inspection hole so I can test clearance around the pipe.

Seems reasonable. Just goes to show that you do need to be vigilant though.

He says he can kango out a strip to take the lintel and the outer course of bricks on the one affected strip. That's acceptable. Contractor did wonder why he didn't just go down a course in the first place...

Let it be known - this is tha last time I ever hire in a general builder, directly or indirectly. I don't think my heart can cope and it does not do anything for my already dim view of much of our species...

[Jim K]

mmm!!

because he couldn't be arsed? he has agreed a set price and was (and probab ly will still be) looking for any way of saving his time and materials to s crew an extra "mcdonalds" out of the job....

welcome to uk.d-i-y again Tim ;>))

Would have loved to have heard the conversation had you reserved the 2 page s from Part H until "necessary" but then that would have been even more str ess and knowing what a twitchy bunch of c*nts they can be they would probab ly have walked off the job or similar.

My hard earnt cynical top tip now is - remain vigilant for more bodges/shor t cuts/revenge or other "so you think you know do you" BS from now on...

Jim K

[Tim Watts]

On Thursday 01 August 2013 10:44 Jim K wrote in uk.d-i-y:

Daft thing is that he has mixed more concrete than necessary, and will now (as agreed with the contractor) have to kango out a strip 3m x 1 brick deep x 1 brick wide. Not much of a time saving.

Mixing less concrete and laying 3m x 1 course of bricks would have been quicker.

Yep. Trouble with a job like this is it would never happen if I did it. That's why I contracted out...

Yes. My leverage is limited having put down 25% of the job cost as a deposit. But I think the main contractor means well. He just trusts his builder too much. Whereas I trust no one!

Yep...

Even SWMBO went apeshit about the exposed foundation along the lower edge. And she said the job looked "rough" compared to my gullies. I'll take that as a compliment - but I did counter than noone cares what footings look like as long as you don;t see them :-o

[sm_jamieson]

You can encase the pipes in solid concrete or rigidly in a wall as long as there is a rocker joint either side (in practice just a push-fit seal). Or between two encased sections some compressible board. I had to do similar w ith a shallow bit of drainage in my floor slab. Not sure if this is allowed under foundations though. Simon.

[Tim Watts]

On Friday 02 August 2013 10:03 sm_jamieson wrote in uk.d-i-y:

Yes - I did come across that in Part H.

Anyway - the builder has told me exactly what he did:

1) Stopped the deep foundations either side of the pipe with plenty of clearance (pointed out either side). 2) Found the pipe already covered in >=3" 10mm shingle (that's about right - I saw the pipe going in a few years ago). 3) Left the shingle in place and bridged the concrete over the top from either side.

Now perhaps the only thing I might have done extra is bung some wire mesh in, but the concrete bridge is likely to be a foot thick so I don;t really see any issues. My house foundation strip has excavations under it (and through it in one area) and that does not have wire in either.

The only thing is I have not personnally seen it with my own eyes, which is a pity. I'm loath to kick up a fuss and make him expose the work[2] as given

1-3 above were what we discussed on the phone when he decided a lintel was not easy - I see no particular reason that he should make it up - nothing to be gained - and his descriptions of what he found were accurate. His work seems competant[1] in other areas, so I guess I will have to go with trust. No normal mortal would even have questioned this anyway.

And the pipe is trivial to monitor for problems as there's a pit 6" away!

[1] I raised the problem of the footings being level with the ground on the low side. He agreed and switched the concrete lintels for catnics which will be hidden. I will not fuss over 1cm of footings - I can tweak those with some soil anyway. [2] He's still got to dig out the floor slab to the tune of 200mm anyway - I can always request a little extra next to teh affected area "just for the record with a photo". Hopefully that will not cause too much offence.

Needless to say, I am working from home for the next few days to keep an eye on everything else.

[The Natural Philosopher]

when we ran drains under the walls here, the pipes were packed round with shingle, and we used 'window lintels' to bridge over them and support the masonry above. BCO was happy with that.

[Hugo Nebula]

Either:

A) It's an exempt conservatory, and the BCO won't call out.

B) It's a non-exempt conservatory, and the BCO should have been looking at the foundations before concreting including the correct way to protect drains under buildings.

If the drain serves more than one property it is (from last October) the responsibility of your sewerage undertaker. Whether they require a formal building over agreement is down to them, but they may not be too chuffed if the conservatory's foundations cause damage to their drains.