New soil pipe through or under foundation?

[Jord]

Hi,

I'm installing a new soil pipe it our 70s house, which has a crawl space.

 

I plan on going through or under the foundation, which is the best route?

 

Is there any standard procedures/diagrams to follow?

 

Thank you!

Edited October 6 by Jord

[Nickfromwales]

20 minutes ago, Jord said:

Hi,

I'm installing a new soil pipe it our 70s house, which has a crawl space.

 

I plan on going through or under the foundation, which is the best route?

 

Is there any standard procedures/diagrams to follow?

 

Thank you!

Is the invert low enough for you to go under? If not, you’re forced to go through.

 

Some pics or a rough drawing would help. 

[Jord]

3 hours ago, Nickfromwales said:

Is the invert low enough for you to go under? If not, you’re forced to go through.

 

Some pics or a rough drawing would help. 

 

Hi Nick,

 

I've not started the dig yet so unsure on the actual depth but happy to dig out where necessary if i need to go lower.

 

I set my mind on going through the foundations with the BR's requirement of 50mm clearance around pipe would mean a +210mm hole into my foundation which I wasn’t too keen on!

 

If I were to go under and run the 110mm pipe though a sleeve, what material is suitable for this? Does it need to withstand high load or is PVC suitable?

 

Thank in advance.

[Nickfromwales]

Making that size hole through founds isn’t going to hurt it tbh, been done a million times before.

 

My point being you need to know the levels (inverts) before you start so you know where you’re able to go through (at what depth).

 

Me personally, I’d rather go through than under. You can hire a core drill to offer minimal disturbance.

[Jord]

On 06/10/2025 at 15:09, Nickfromwales said:

Making that size hole through founds isn’t going to hurt it tbh, been done a million times before.

 

My point being you need to know the levels (inverts) before you start so you know where you’re able to go through (at what depth).

 

Me personally, I’d rather go through than under. You can hire a core drill to offer minimal disturbance.

 

Hi Nick,

 

That's great thank you! Will start digging down over the weekend and see what the best route is.

 

Appreciate the advice!