Is this a problem expanding foam can fix?

[SeLHopeful2024]

Trying to work through some issues in our new house (on a shoe string as we wait for big jobs to be done).

Downstairs toilet is ridiculously cold, despite having a radiator most of the width of the wall.

I've noticed there is a big gap between the wall and the toilet waste pipe.
Would this be part of the issue, and would expanding foam into the hole fix it?

Any advice on better solutions to block it up?

It's very difficult to get in there as the room is little more than the toilet width.
Taking the toilet off and doing anything is not an option for now as we have bigger jobs that are more of a priority.

Thanks for any help.

If that hole goes all the way through the wall to the outside you will get rodent visitors. I'd fill it with steel wool and that stuff for filling holes round pipes, not expanding foam.

Expanding foam aspires to world domination, you squirt a tiny bit and it just grows and grows and grows until you can't see the toilet.

Expanding foam will be fine for this job, just use a small amount and let it expand you can always add to it. Leave over night and trim off flush with the wall with either a hand saw or a bread knife.

You'll never get a nice finish with expanding foam unless you are prepared to do a lot of work! I'd oack the hole (steel wool if you are worried about rats or mice) and the use filler to cover it, sand and paint.

Last post is 100% right, I do lots of diy & that's what I'd do. Expanding foam is over the top for this comparatively small gap. If you pack it with steel wool e.g www.screwfix.com/p/essentials-multi-material-grade-1-medium-steel-wool-150g/186rl
Then you want something like www.screwfix.com/p/toupret-ready-to-use-filler-1-5kg/812pp
Fill with a filling knife (screwfix also do these) then when you've packed it in wipe over gently with a damp sponge to get a smooth finish

Thanks everyone.
It doesn't go directly outside. It is on an external wall at the front of the house, but no obvious sign of it from outside.
That said, I appreciate the thoughts of rodents as I'm sure they could still get in if there's any other gaps into the wall.

Steel wool and filler it is.
The previous owner has botched the wall already in there, so I don't want to make things even worse for when we do get round to decorating in there.

For everyone saying expanding foam is hard to control using an expanding foam gun makes it very controllable as it has an adjustable knob that controls the flow. Screwfix sells the gun, the foam and the foam cleaner meaning cleaning up the gun is easy.

Toupret wall filler and wood filler (for other jobs) are great products.