How long can chicks stay in a 6x2.5' brooder?

[blessedmamato3]

The coop still needs the roof finished, nesting boxes made and siding on and the chicks will be 5 weeks on Wednesday. My hubby works 2 jobs and isn't home much. I can do the siding, but not the other stuff. How long can we keep them in the brooder? There are 20 of them, 5 of which we got for meat. They have plenty of room right now, but dang, they grow so quickly!

Here's a picture of them doing their thing...

 

[Mahonri]

Well as you know they are crowded... the sooner you get them out the better... can you make a small tractor for your meaties? that might help a bit.