so i was planning with my dad for my coop-to-be, and i said we needed to paint it too, inside and out. He said that it was fine to paint the outside, but he didn't think we needed to paint the inside.
What do i do?
It looks nicer to have it painted inside, but it's not necessary.
Perhaps your dad is thinking about the cost of painting both indoors and out. If you aren't too particular about color, you can often get cans of "mistake" paint very inexpensively from a hardware store. Try looking at a Habitat for Humanity ReStore store, too, if you have one in your area.
Prime first. If you have paint, then for sure do the interior. It will be so much easier to keep clean. If you buy paint, get exterior grade, preferably in a semi-gloss. It holds up to weather fluxuation and will be much sturdier. Make sure you do the floor too. But seriously, prime first.
What CityChook said. It is MUCH EASIER to get poo off of painted than nekkid plywood. I'd use semigloss, preferably some sort of light color to brighten the interior of the coop for the chickens' benefit. Prime first!!