These generalizations are too sweeping; it very much depends on the kind of plastic, and the kind of wood, and the design. For example, painted wood doesn't breathe either (unless you've used a special kind of paint); rotten wood is very bad for the health of any birds in it, and fungal spores can live in and on it; but I would agree that wood is definitely easier to modify the design. Your neighbour's shed may not be a representative example given there are 7 common types of plastic. Can I suggest you have a look at this site https://nestera.co.uk/ Do you really think they would be partnered by the RSPB, The National Trust, the BBC, wildlife trusts, the Chair of the Poultry Club of Great Britain, and others if what you think about them were true of them?I don’t like the idea of plastic coops bc:
The only advantage of plastic coops I see is mite control. I use DE as a paint & under the bedding in the nestboxes for lice/mite control. So far it works great for me (7 years).
- The inside climate is not nice and healthy compared to wooden coops. plastic doesn’t regulate moisture. Imagine yourself in a plastic cabine and a wooden cabine. What would you prefer?
- Plastics are bad for the environment. Even the better recycled ones had a con. Because the tiny particles that come off, go everywhere.
- Plastics degenerates. How quick depends on the quality. Wood (if dry) has a longer lifespan. The lifespan of many plastic products is really short just because of differences in tensions in heat /cold. It often breaks near hinges or other critical points. (My neighbours bought a shed that lasted just 2 years).
- Wooden structures are easier to repair or to adjust.