How to mesh off air bricks? Rats.

B0bbyEwing

Trying to think how rats are possibly getting in to our house & am drawing blanks.

The majority of the time we hear them either in the living room walls or under the living room floor (not sure which tbh) or in the extension (which is solid floor) walls - always around the skirting area. I don't really have access to these areas.
They've occasionally been under the bathroom floor which I have a little access to and they've been in the loft - which I have the best access to and is how I've caught them before. 

Our air bricks are square holed & on Googling I read that mice need a 1cm2 hole to get through (which would be the air brick) but rats need a 2cm2 hole to get through - so the holes on the air brick would be too small.

Regardless, I've thought about meshing off the face of the air bricks 'just in case' but I'm not sure how you'd tie it off so the mesh is secure. You could send a metal tie through but then you need to bring it back through towards yourself to be tied off & as I've no access on the inside of the air brick, I'm stumped. Unless there's some kind of product out there that I can't think of that would do this job?

I've considered the drainage system as a possibility but this couldn't (surely?) be connected to the living room underfloor because then you'd have sewage all under your living room floor, so the only other entry point to the house would be the bath/sink/toilet - which they'd then get in to the open house, which they haven't done.

My wife suggested going up the drain pipes, up the wall of the house & then in to the roof area that way, which would then give them access to the walls etc of the whole house, but can they really climb up a plastic pipe the height of the house? I'd have thought there'd be nothing for it to grip on to but what do I know. If this is possible then maybe something to wrap around the pipe somehow to stop any rat climbing beyond that point. Know of any products here?

Short of these 3 possibilities, I can't think of anything else really. There's next door but I imagine it's only the same possibilities as ours (they have had bother with mice/rats but I don't think it's nearly been as much as us). There's no obvious holes in walls externally where they've tunnelled through. 

Reddleman79

B0bbyEwingn

You could send a metal tie through but then you need to bring it back through towards yourself to be tied off & as I've no access on the inside of the air brick, I'm stumped.

Like this.

tacpot12

I've used external silicone sealant to fix mesh over the airbricks for my step-daugher. Apply a bead around the outside of the airbrick and gently press the mesh into it. It's still there two years latter and showing no signs of becoming detached. It looks like it will be there for good. The mesh is not so good. I bought a cheap stainless steel mesh of eBay and it has gone rusty!

MikeJXE

They could be getting into the floor via the service duct that brings electric gas and water from outside to inside under the floor boards

MouldyOldDough

I bought these anti-wasp covers to stop wasps - RATS would struggle to get through as well

RATS are too large for normal vent holes

https://www.amazon.co.uk/s?k=Mousemesh

they are well built and will last for years

ThisIsWeird

Hi BE.

I think I'd be inclined to first try some cheap plastic mesh, temporarily fixed over the vents using silicone or similar. This won't stop a rat or mouse, but it will certainly tell you if that's how they are getting through - and I suspect it isn't.

If the thin plastic mesh remains untouched, you need to look elsewhere, and around waste and water pipes coming through the floor is, I think, the most likely bet.