Mould everywhere

[pilgrimhudd]

Your garage may be dry but if it isn't insulated there will be temp fluctuations and condensation which is what mould likes.
Floor, walls and roof are cold bridges, the roof and walls can be insulated between rafters/studs with celotex but floor is more difficult unless you raise it by battening and celotexing in between then cover with ply.
Maybe easier to make an insulated storage cupboard.

Yeah this is my problem in my brew shed, though I brew outside the shed itself is very damp (despite it being well ventilated). The temp fluctuates widely and I get awful condensation.

When I get a bit of spare cash I plan to convert my garage into a liveable space by insulating walls/roof/floor, and then sneaking my brewing kit in when the mrs isn't looking.