
You live in where it gets cold, you may want to consider insulating (double wall w/plywood). Assuming you'll be closing off the "ceiling" (insulate) or you'll have them getting up there. Sealant "smells" maybe several layers latex paint or even that BullsEye primer (although it's white) but it wipes clean. I chose not to paint inside, they'll peck at the walls/paint for sure. IF you do paint, make sure to ventilate to dissipate the smell. For sure paint several coats outside for water proofing.
What are the dimensions? Will you be adding a run? Suppose you've read about the 4sqft per in the coop with 10sq ft in the run, helps to alleviate flock issues.
Instead of walling off the front, you may want to keep it open or separate the sections with wire, so it doesn't feel "closed in". Roosts should be about 2' - 4' high; not above the nest boxes; although I've seen higher. My thinking is the higher the harder the landing = bumble foot or injury. You may want to figure on a poop board under the roosts, will save alot of time cleaning.
I prefer pine shavings to sand, sand would be easier to scoop but harder on the landing & gets "solid" when wet. DLM (deep litter method) is the way to go, rarely having to clean, they do most of their pooping while on the roost at nite ... I had a had a poop board once but having only 4 now I relocated the roost and that's where I pickup the poop first thing in the mornings ... Poop board with a 2" lip w/PDZ makes it very easy.
Look into the Horizontal Water Nipples ...
horizontal water nipples for chickens
not the Vertical. Less water cleaning and mess in the coop. Best of Wishes, glad you're doing the coop before the chicks ... Chicks grow faster than the building of the coop
