Can I stop birds from nesting in a chimney in a cottage due to be demolished without going on roof?

[joe90]

3 hours ago, scottishjohn said:

a suirrel could run up any sort of pebble dash

Oh yes, my last house had pebble dash and squirrels used to run all round the house (outside) on the pebbledash.

[saveasteading]

We are talking red squirrels here, and also pine martens. From what I have read the swallows are not programmed to see a box on a tree as an option anyway.

Perhaps a big, insulated  box constructed on the outside of an outbuilding would do.