For us to decide to build another coop because of chicken fever and chicken math! This year was our first year raising chickens and our girls are just about to the point of lay. We built a nice coop to comfortably accommodate 11 chickens. Well it didn't take very long for my brain to start twitching that "it would be so nice to have another coop to get some more breeds and to make a nice environment for more silkies". So now I just ordered 7 more chicks to arrive in the spring. There you go...2 coops in one year to accommodate 18 girls. I've gone cookoo crazy for sure!