He doesnt pressure wash currently, we were only going to do that with a plastic shed that we could have dried out completely. For the wooden playhouse the chickens live in currently we use the mite powder, and mite solution sprayed into any cracks. We also dust the hens regularly.
The playhouse they are in currently is 5x5ft, technically big enough but I prefer my girls to have more than adequate space than just sufficient!
Wouldnt sheet metal sheds get horrifyingly hot in summer?? I hadn't even contemplated metal for that reason!