Birds in shed problem

I have a problem with birds getting into my workshop / shed, (the feathered kind unfortunately) They have pushed out the foam packers at the base of the roof and when the packers were glued the pecked them through, the little devils are nesting behind the H beams and I want to stop them before breeding season.
the roof is big 6 fibre cement and the shed is 30' x 40' box profile. Dose anyone know of bird proof packers or any other means to keep them out, short of a pet Pinemartin.
Thanks in advance,
Ronnie.