How safe is coring a 100mm hole in this wall?

[Jaygray]

Hi All,

I'm looking to add 100mm ducting under my suspended floor and as such need to core a 100mm hole through my solid wall..

I wouldn't be concerns, but last year I also cored a 100mm hole for a new soil stack which will be roughly 1.5m from the new one.

I'm looking to core where I've highlighted in red. Any advise welcome.

 

[footprints]

Looks a bit near the DPC, what about water ingress? Traditional air brick about 65mm (a brick size) 100mm almost two bricks.

 

[Jaygray]

I can go down a bit to avoid the DPC. Is it likely to cause structural weakness being so near to the other?

Alternatively, I can add another air brick. Does that carry less risk?

 

[footprints]

I would think that removing one brick and fitting an airbrick would be less risk than a 4" hole, normally they are just under the DPC level, if too low any flooding along the path could run under your floor.
Any particular reason you need an extra air brick?

 

[Jaygray]

I have terrible crossflow ventilation because of a shallow crawl space and no end of sleeper walls prevents air movement.

 

[footprints]

Can;t see the soil pipe hole in the pic but as you say it's 1'5 metres away I can't see it doing any harm, when fitting the old boilers we used to knock out 9"x 9" holes in walls and none fell down.
OK I am not a structural engineer but I would be quite happy to put a brick sized air brick in if it was me.

 

[foxhole]

I have terrible crossflow ventilation because of a shallow crawl space and no end of sleeper walls prevents air movement.

What damage is this doing ?

 

[Jaygray]

Rotting timber joists and condensation.

 

[Harry Bloomfield]

Is it likely to cause structural weakness being so near to the other?

Unable to see 'the other' in your photo, but better than a core, cut a brick out below DPM, but clear of any likelihood of letting any water in - through both leaves. Replace with an air brick.

 

[noseall]

Is it likely to cause structural weakness being so near to the other?

No.