Can I fill the void behind my facia / soffit?

[Amped]

Hi all

I have an issue with mice coming in from my neighbours loft space. They refuse to do the honourable thing and throw themselves into a trap, or eat any poison, so I'm looking at blocking up their access.

I believe they are using the void behind the soffit / facia to come and go and I need to fill that space along the party wall.

I can barely reach into the space from the loft, and don't have any external access due to a conservatory beneath, which can't be scaffolded over, so I was thinking about filling the space with expandable foam. I'm aware that any rodent can easily chew through expandable foam, but I'm hoping it will be enough of a deterrent, as they are only occasional visitors at the moment.

So my question is this: will filling that void with a big splodge of foam cause any air flow / condensation issues? Is the space needed for airflow etc? Will the foam cause any issues where it meets the roof felt or the soffit? I believe the soffit is made form a concrete tile, probably full of asbestos.

I'm worried I fill in the space, cause a damp / condensation issue and am unable to get into the space to rectify it.

Hopefully the attached diagram makes some sense. The red chevrons are where I'm wanting to fill in with foam.

Any help or info is greatly appreciated!

 

[blup]

Fire rated expanding foam? They might not observe human ownership boundaries and already set up shop on your side though.

Blup

 

[^woody^]

All vermin will chew through foam or suchlike and it won't take long. You'll need a fine steel mesh too. Also, any gap left will be taken advantage of, and typically its very difficult to seal eaves unless you take the tiles off for access.

Commercial bait traps do work.

 

[Amped]

Fire rated expanding foam? They might not observe human ownership boundaries and already set up shop on your side though.

Blup

Don't think they have set up shop yet, the noise is very intermittent. I'm hoping the foam will be a simple deterrent rather than a full proof solution.

 

[Amped]

its very difficult to seal eaves unless you take the tiles off for access.

So sealing eaves is something people do? It doesn't cause any air flow / condensation / damp issues?

 

[^woody^]

So sealing eaves is something people do? It doesn't cause any air flow / condensation / damp issues?

What you are proposing - sealing eaves between the property boundary is what should be done in new build and refurb work nowadays to prevent fire spread.

The other sealing eaves - under the roof line, is different, and I wouldn't say that it's common, but some people do do it for insulation reasons.

 

[Amped]

I wouldn't say that it's common, but some people do do it for insulation reasons.

Thanks, good to know.

After some time away from this with other work issues, and no sign of said vermin for some time, they have now returned and this will have to be dealt with.

I'll just have to go with the fire rated expanding foam and see how I get on.

Wondering if it might be bats or something else that doesn't want to go into a trap, but even with a camera trap I have been unable to catch whatever it is up there.

 

[datarebal]

Just hope they don't scoot along at ridge level ,

 

[Amped]

ridge level

Can I fill that with foam?