We decided after 6 months into hen keeping to ditch the wooden hen house. Our big hens live in a 6 x 4 plastic BQ shed bought on offer and easily converted to purpose ( one wall has a window , which if you install upside down becomes a pop hole with a bit of imagination to cover the hole. Already vented on two sides, only problem is a bit of condensation in the winter but a battery run expelair thing help with that. The silkies live in a converted plastic garden storage seat .
No red mite problem in 3 years , both are so easy to clean, even in the winter, especially the shed .
Red mite can be in plastic houses but are easily eradicated on the smooth surfaces.