Mouse/rat proof silicone

Colm R

I had a new external boiler installed last year, and the pipe work and electrics associated with it go through the external wall through a pipe that use to be the waste pipe for an old toilet. The pipe itself is cut flush with the wall on both sides.

The space in the pipe is mostly taken up with the pipework for the boiler, but there is enough space for a mouse to fit through.

I can only access the waste pipe from the inside under a kitchen press, but not from the outside, as the boiler is positioned there, flush with the wall.

Filling with concrete will be difficult as it will be hard to get it in there.

Is there anything that I can get to use with a silicone gun to fill this space, and more importantly, mice and rats won't eat their way through?

Wicklowandy

Ive used chicken wire and expanding foam on the recommendation of a friend who works for rentokil. Stuff the chicken wire in tight (careful / use gloves, its sharp!) and liberally apply expanding foam. Worked for me;)

jack of all

I think the expanding foam and chicken wire is a very good idea as it is reversible- just in case you ever need access for repairs or maintenance. Also it would be a bad idea to have concrete in direct contact with any bare copper piping due to the risk of the alakalis attacking the metal over time.

antoinolachtnai

Another thing that was recommended to me for small gaps (and which seems to work) was simply to pack with steel wool. This might be a bit less messy than the foam if the space is small. And you can pull it out easily enough if access is needed.

Filling with concrete wouldn't always necessarily keep rats out. You'd need to put some broken glass or something with it to be sure.

Joey the lips

steel wool or glass. I would try glass.