We have a 1930s suspended floor construction. Pretty much like the construction seen in the attached image.
I laid my new mdpe water pipe in a trench in the front garden, and passed some ducting (110mm soil pipe) under the porch, an v it had to go under the footings of the outside wall. I made a hole just about big enough to pass the soil pipe through.
Do I need a lintel over this pipe, or should it be ok given that it's only 140mm hole. Access would be a knightmare to dig this out properly. From the outside I have to squeeze between the garden path and garden wall where all of drainage, gas, electric and water pipes run, plus having to go underneath the porch which is 1m depth.

From the inside it isn't much better. Would have to pull up all the floor boards and work between joists, digging out 100mm of concrete.

Perhaps I can try and put some concrete between the tiny gap between the top of the pipe and the footings?

To late for you, but I used a INSUduct and Groundbreaker 3 to avoid having to go in under the floor.

I know that this gets done, the web is full of debate about burying PVC pipe in concrete etc..

e.g. http://www.homeownershub.com/maintenance/pvc-pipe-buried-directly-in-concrete-326469-.htm

Personally I'd avoid having concrete in direct contact with PVC pipe: if (when...) shrinkage occurs, the pipe could be subjected to pressure which over time could result in embrittlement and eventual weeping. Imagine some time in the future sombody pouring boiling water or hydrochloric acid / drain cleaner down that pipe... Therefore I'd wrap the pipe first with something soft, or paint it with bitumen etc.

I have had terrible problems with PVC wastes being laid directly through 6-inch poured concrete walls, a nightmare in fact. The only happy person is the painter... Use a sleeve !

gg

PVC wastes are a lot weaker then underground drain pipes.

Posted By: gyrogearought-I to delete my irrelevant "contribution"

No, don't - I didn't know that you shouldn't put waste pipes nude into cement - would probably have done so in the next 6 months without your 'irrelevant contribution'.

Posted By: JT101I don't know why it can't enter higher if it is insulated e.g with Armaflex or Insuduct,

because 750mm is considered below the frost line, and higher could be subject to frost. Insulation only delays freezing doesn't stop it. If you go away for your winter skiing holiday the insulated pipe above 750mm could still freeze - any insulated water pipe will freeze unless the water flows sufficiently to replace the (slowly) lost heat through the insulation,

PS Personally I would not put a bridge over the soil pipe ducting the water pipe. IMO the foundations should be able to take a hole for the soil pipe without integrity issues. And if they can't how much damage / weakness will you create putting in a bridge as a retrofit. I assume the foundations are mass concrete and not concrete bulked out with rubble and alike.

Hi Peter

Thanks for your response. That clarifies that. It's hard to say really as I can't see much, but once I got down about 500mm below the concrete slab, I was able to dig through soil. There was definitely some hardcore there just before I reached this point but whether this was part of the concrete footings or just a hardcore layer I'm not sure.
It seemed too shallow to accomodate both hardcore, concrete and a few courses of bricks based on the image above so it must be part of the concrete footing. Given the build quality of some older houses, I wouldn't be surprised. I'm sure they chucked any old stuff in there.
Anyway, I'll try and shove some small pea shingle around the hole. Now way I'll get any concrete in there anyway without further excavation.

Great, that's what I wanted to hear. I'm not taking your word for it, but now I've spoken to several people in different parts of the building trade and that's the general consensus. In hindsight Insuduct or a Lintel may have been the way to go. Actually asking a structural engineer before I started the work might have been an idea but I didn't think too much of it at the time. The gremlins in my mind came afterwards. I've bought some 10mm pea shingle which I'll do my best to cram around the pipe. Nice one everyone, cheers for your responses.