Drain through wall

[acurachris]

Hi

I'm running a drain through the footing walls and i'm stuck on the section of the building regs that states "openings masked with rigid material and around the pipe should be compressible".

Rigid Board
I've heard people mention cement board but will this not perish after a few years sat in damp ground? Would a piece of rigid insulation work, how long would that last in the ground? Plastic is about the most durable material i can think of, but this could be a pain to cut/work with.

Compressible Material
I've read that 10mm pea gravel can be considered a compressible material, is that correct ? People have mentioned insulation, will this be durable enough in the ground?

Surely this is a common occurrence so what do most builders use? When you see pictures of drains running through walls (my internet search history is looking rather odd ), they typically show just the drain running though the wall; so either builders don't take pictures after fitting the rigid board or they don't do it!

Cheers, Chris

 

[tony1851]

I think it's one of those details which is easy to draw in a diagram, but difficult to do in practice, and probably unnecessary.
If you want to try it, polystyrene 50 thick would do.

 

[acurachris]

polystyrene 50 thick would do

Do you mean for masking the openings? Will the insulation not soak up water? The backfill is going to be against it. This is what i don't get, there doesn't seem to be a logical rigid sheet for the job.

 

[tony1851]

Do you mean for masking the openings? Will the insulation not soak up water? The backfill is going to be against it. This is what i don't get, there doesn't seem to be a logical rigid sheet for the job.

Polystyrene board is OK for use underground. It is often placed in sheets against below-ground walls in clay soils where tree roots are near. When the ground moves slightly over the seasons - as clay soils do when trees are present - any sideways pressure on the wall is lessened by the compressible polystyrene.

 

[acurachris]

That makes sense i suppose. Thank you.

 

[acurachris]

Will the jablite boards work, or are there specific types to use?

 

[John D v2.0]

Even The polystyrene packaging you get with new appliances would do, its just something compressible torepel the concrete.
You are supposed to ensure rats cant chew through though.

 

[acurachris]

its just something compressible torepel the concrete

It's not to go through a foundation, but through a linteled wall in the footings. It's to cover the hole where the drain enters and exits under the suspended floor, so no concrete will really be against it. I guess vermin could just chew right through the insulation then.

 

[Notch7]

I think builders use rockwall insulation batts wound around the pipes

It wont rot....its made of rock!

 

[Ian H]

If it were me i’d build a piece of 6” pipe into the wall and put the 4” through that, then stuff the gap with rock wool.

 

[acurachris]

If it were me i’d build a piece of 6” pipe into the wall and put the 4” through that, then stuff the gap with rock wool.

That's a good idea although the regs say it has to have 50mm around the pipe, which is odd as it also says, mask the hole you make with something rigid (which in effect restricts the movement!). I think your idea is better but building regs want it done differently.

Maybe i'm overthinking it, I'm good at that!

 

[tony1851]

The reason they ask for 50mm clearance is incase the wall settles over the pipe, or the ground heaves up slightly, pushing the pipe upwards.
But IMO if either of those two scenarios happened, you've got bigger problems than a leaking pipe!

 

[Ian H]

I’ve seen clay pipes that are built into the wall fracture by moving a couple of mm. Any that drop further than that do it because the fracture leaks and the ground gets wet.

Doesn’t matter though, rules is rules.

 

[noseall]

I think builders use rockwall insulation batts wound around the pipes

Correct. You just need to create a flexible buffer around the pipe. Whether it eventually rots or not only matters if it allows vermin access.

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[acurachris]

Cheers for the input everyone. It’s been very helpful.