Soil pipe exit

[bogartslip]

I would really appreciate if someone could advise. 

I intend to install a downstairs toilet for my elderly mother, unfortunately it won't fit under the stairs so it will have to go in the back dining room. I intend to build it in a corner opposite the windows,  this means I will have to run the soil pipe along the skirting party wall for about 2 metres  then out through the external wall then into the soil stack about 2m away.

The problem being , will it be OK to drill a core hole ( probably 125mm) in the corner of an external brick wall , one side being the party wall and the other being the   back external wall. Would there be any structural issues as both will probably be load bearing walls. I'm trying to keep the number of turns on the soil pipe to a minimum as it's gravity fed toilet. 

Cheers

[nod]

Core drilling a hole won’t make any difference to the house structure 

[bogartslip]

Even if it's in the corner of 2 load bearing walls?

Thanks 

[Nickfromwales]

None whatsoever. Done so many core holes through masonry I simply cannot remember the number!! Whether you choose to open the can of worms by asking the neighbours permission is up to you....

 

IIRC a 127mm diamond core drill leaves you a hole which allows the knuckle of the pipe fittings to set into the wall, so look to hire / buy at that size. Measure the fittings as some manufacturers have smaller knuckles, and some are much 'fatter', requiring bigger holes.

 

Be sure to seal the external hole with sand/cement mortar, and the internal one with foam; if a cheap BM foam then do not let it ooze out into the cavity (less is more!!) and just seal a few inches in.

 

You will need a 105mm hole high up too, as the space for the new loo will need extraction for B regs compliance.

[Temp]

12 hours ago, bogartslip said:

Even if it's in the corner of 2 load bearing walls?

Thanks 

 

No not unless the corner is just a small pillar between two large doors

[bogartslip]

On 28/09/2025 at 22:04, Nickfromwales said:

None whatsoever. Done so many core holes through masonry I simply cannot remember the number!! Whether you choose to open the can of worms by asking the neighbours permission is up to you....

 

IIRC a 127mm diamond core drill leaves you a hole which allows the knuckle of the pipe fittings to set into the wall, so look to hire / buy at that size. Measure the fittings as some manufacturers have smaller knuckles, and some are much 'fatter', requiring bigger holes.

 

Be sure to seal the external hole with sand/cement mortar, and the internal one with foam; if a cheap BM foam then do not let it ooze out into the cavity (less is more!!) and just seal a few inches in.

 

You will need a 105mm hole high up too, as the space for the new loo will need extraction for B regs compliance.

Cheers, mate. I suppose my concern is not compromising the corner of  load bearing walls. 

[Nickfromwales]

10 minutes ago, bogartslip said:

Cheers, mate. I suppose my concern is not compromising the corner of  load bearing walls. 

You won’t. If you were using a kango demolition hammer I’d be slightly worried, but either stitch drilling it or diamond core drilling will be zero detriment. 

[saveasteading]

On 28/09/2025 at 13:04, bogartslip said:

Even if it's in the corner of 2 load bearing walls?

 How close to the corner?  Of course a wall with  a bit missing is not as strong as a whole one.  I wouldn't want a hole in the corner 'brick and a half' zone. 

But a neat hole further away is fine. Think of the load going down through the wall and half of each brick loading the one on either side, and so on. the loads goes around the hole and returns to being spread. V

ery near the corner doesn't. If it is a cavity wall then you wont get through right at the corner anyway. allow this. If it is very close can we see a picture?