Walls over drains

[Pete]

Hi

I know how to bridge a foundation/brick wall over a sewer pipe if the are at right angles to each other,but would like to know how close ca foundation/wall be put to a underground pipe when it run parallel to i

-- Pete

[Peter Taylor]

The bottom of the foundation must be at least 150mm below the bottom of the drain so it will be bearing on solid soil and won't put any load on the drain. That way you can go as close as you like, although put some formwork in between to stop the concrete surrounding the drain. And take care not to move or damage the drain, especially if it's an old stoneware one.

[Rick]

Assuming its house walls, there are some rules depending upon pipe depth, but from memory 1m, but please check, as it depends upon the relative depths of the pipe compared to the foundation.

Rick

[The Natural Philosopher]

Huh? Mostr of mine run almost alongisde...

[Rick]

At ground level I guess thay can, I guess its about not undermining the foundation when you dig the trench.

Rick

[Peter Taylor]

"Rick" wrote

True, but the question was how close can a foundation/wall go to an existing drain - not the other way around.

[The Natural Philosopher]

Well we dug the foundations a LOT deeper than the drains.

But that of course was a new build with modern foundation depths. At least 1.2m and up to 2.8m in places where trees are.

[Charlie]

There are detailed Building Regs at:

at section H 2.25 onwards

Hope this helps

Charlie

[Peter Taylor]

Charlie, this reference to the Building Regs relates to laying drains near existing buildings, so as not to weaken the foundations. The OP wants to know how close he can dig a foundation to an existing drain - it's not the same question. New foundations are covered under Part A.

Peter