Brilliant! Now the only job left is for you to come and build me one the same!
In answer to your questions:
1. What size should the opening into the nest box from the main coop be? At the moment it is 28cm high x 90cm long (the nest box is higher when they are in there, 45cm)My chickens like an opening around 30cm x 30cm because they seem to like to squeeze in somewhere private and cosy to lay their eggs. If you divided your nest box into three equal parts it would be perfect, in my opinion. Or you could just divide it in half (see below).
2. If I get 3/4 chickens, will 2 nest boxes be adequate or should I make 3?Five of my pullets are currently laying in one nest box (although there is an identical one right beside it that nobody uses.
) My sixth pullet lays her egg in the garden.
The conventional wisdom is to have one nest box for every three or four hens, so two nests should be plenty for yours.
3. Should I leave the the openings between the Coroline sheeting open for ventilation or seal them?Are you sure no rain can get in? If so, leave the gaps open for ventilation. But while you have the coop apart for painting, line the roofing with mesh so small wild birds, rats and mice can't sneak in through those gaps.
Also while you have the coop apart look up Hillfooter's recipe for Diatom Slurry. Paint all the internal parts of the coop (including nest boxes, perches, floors and walls). This will be your first line of defense against red mite and I thoroughly recommend it.
Now some questions for you:
Do your nest boxes have a nice deep lip to stop your girls kicking the bedding out? (And a lip at the back to stop the eggs rolling out when you open the door of course!)
How will you clean out the coop? Is one of the sides (or the roof) hinged?
Are your perches nice and fat? Hens don't roost on something the size of a broomstick. They need something more the size of your leg! (oops I think I just called your legs fat
)
Seriously though, that is a beautiful looking coop and I'm sure it will be very practical for you and your chickens. Great work.