I have 13 hens and 1 rooster, they are 8 months old. They've been in their coop for 6 months now with no issue. I noticed about 2 days ago that their coop smells strongly of ammonia. I keep water outside and use sand for the poo shelf under their roost and the floor, and pine shavings for the nest boxes. It's 14 sq ft and when we built it we ventilated it pretty well. All has been well until a couple days ago. No leaks that I can see anywhere, so what gives? I put the sand in six months ago and added some pdz to it. I scoop it regularly, floor and poo shelf. The sand in the shelf seems to be depleting a bit but other than that..no change in anything. I try to turn the sand floor about once a week for upkeep so it doesn't become packed down. It was fine Thursday, Friday I opened the doors and suddenly smells ammonia-y. Any help is appreciated.