A trellis up in front of your house wall will make a pretty, safe place for birds to nest. It should have a gap of 10 to 15 cms (4-6 in) and cover it with climbers like ivy, wisterias, honeysuckle, etc.
This will also create a wildlife corridor at the bottom for small mammals such as mice to wander around safely.
To give the birds more help, leave nesting materials out and about – but not synthetic stuff. They will like wool from old jumpers, feathers, short lengths of string, twigs, dried grass, shredded paper and moss, says The Natural Garden Handbook by Caroline Foley.