I took a real large wooden crate and cut it down to 44 x 42 x 30. It has a wood lid and is solid all around. Nights here are still in the low 30's. Got some chicks coming in about the 24th. I have a red 250w heat lamp in there. Should I install screen in the top for fresh air? The top seals with 1/4" gaps in areas. Bottom has some 1/32 or smaller cracks between boards. What is the overall opinion on drafts and fresh air? It would be easy to put screen in the top to open during the day and close at night, or just prop the lid open some, but I worry about things getting too hot. I was going to put the heat lamp towards one corner to allow alot of area to spread out just for that reason. Only gonna have about 25 or so chicks in there at a time. This is my first time, so I want to to try to do things right.