Paul - just asked my OH what he did with my shed to prevent rodents getting under and up inside. We live amongst farmland and there are dykes here as well so rodents of all types are here and, even having four cats, still can be a problem. What he did was to staple the top of some half-inch welded mesh to the base of the shed, then fixed the bottom of the mesh with strips of carpet grippers screwed to the concrete base using rawl plugs. It's worked so far.
That sounds a good solution.
I dithered about insulating the walls of my potty-shed. When I was a teenager I insulated a 12' x 8' double shed with hardboard and cork granular pieces in between. The mice loved it!
This time I've used blocks of material similar to new build home insulation and hefty plywood lining.
The floor is new sheet material - tongue & grove boards. Hard as nails providing it isn't contantly wet.
The roof has been insulated too.
I'm aware that rodents could enter via the door as well as up along the shed walls if they take time to chew their way in. I'm wondering whether a sonic rodent repelling device might be worthwhile. I tried one in my parents bugalow before they moved and it appeared to do the trick.
I've bought a small hoover for the aviary to minimise the amount of waste seed left about and all food storage should be secure.
I really hate mice.
spottymint I'd love to keep a range of hardy finches as I did way back when.... (I won't go on for a change). This time round I've started with a few budgies with the option of adding another flight on the front of the shed later for finches.
shoozie The hydgranga was a goner... roots firmly fixed below the paved area so I bought three replacements for elsewhere and they seem to be doing ok so far.