a garden shed is fine m8,take the top bit of wood at the back out
and put wire along it [air vent],at the front where the window is
take out and put a sputnic trap and at the bottom cut 2 12x6 holes
and put plastic vents over the top,depends on the size if you have a corridoor
and sections plus put a vent on each side at the top.
inside nestboxes or boxperches [jmo]
also make sure is on blocksof the ground