Rats in the cavity walls

[ucan]

Rats are climbing up between the cavity wall into a flat roof extension from a sewer I have had a CCTV down the sewer but can't see where they are getting up into the wall, I have done the rat posion bit many times but they keep coming, I have removed one brick and I was thinking of putting gravel down into the cavity so it lays in a bed below the ground to fill the space they are getting through, pouring concrete seems a bit extreme and might cause a damp problem, any ideas please.

[stoneyboy]

ucan,
If the rats are getting out of the sewer there must be a hole in it and a smell to go with it.
Councils will generally send round the rat catcher for free so get in touch with them.
end

[joe91]

On TV the other day, I think it was 'Help, my house is falling down', they had a one-way valve type thing for drains, which allows water down, but stops rats getting up. Not sure where to get them though. Try Google.