Turning a dog run into a coop

[dangersjones]

I'm new to chicken keeping and purchased a premade coop for my four pullets at Tractor Supply. It was cute and would look nice in my suburban back yard. The add said it accommodates 6-9 chickens but my 3 month olds are already super crowded. I'm pretty crafty and thought I could come up with a more comfortable.
I purchased a dog run, (4x6x8 feet) and I'm planning on modifying an old dresser to be a nesting box/shelter.
My question is, how much covered indoor space do four chickens need? I live in Central California so it doesn't get too crazy cold. I know they're supposed to sleep on roost bars but they're currently sleeping in the inclosed part of my store bought coop. Help!

 

[Pork Pie]

Your birds will naturally sleep in the enclosed space - thats really what is for. Unfortunately, the number of birds prefab coops claim to hold a grossly exaggerated. Here are the minimum recommended space requirements for chickens, per bird:

Coop - 4 sqft
Run - 10 sqft
Roost - 1 ft

The roosts needs to be in the enclosed space.

Good luck
CT