That's a beauty - won't last long for the chicks though - they will be perching on top of that rain within the week!!! Just my experience. I've used a baby playpen and by the time they are three or four weeks old they are trying to fly up to perch on the edges of the playpen!! Its a beauty though - and will be much easier to clean than the playpen!!! Enjoy.
A little bird netting across the top would make those flights pretty short.