I just finished my Silkie coop last week, made out of pallets, 42 in x 52 in, I have 2 Silkies.
After putting the walls up, I covered the outside with 4 mil plastic, then covered that with 3/4 plywood. The space between the pallets, I filled with hay. I sat in there on a windy day, and felt no draft. The front door faces North, the window faces East (see the pict.)
The back door faces South, and the solid wall faces West, there is where I will put a small nest box for when Nonnie starts to lay.
If you look toward the back, above the door (which I still have to hinge) there is a 2 - 3 inch gap, that is my venting, it is covered in hardware cloth. Just finished fencing their run today, so my big hens will stop breaking in & stealing the Silkies food!
I heard some people talking about some type of inexpensive board, that has a slick white side to it, they said it was easy to wipe down. If you got the foam board insulation, and the covered it with white board, that would give your Silkies some buffer to any wind or cold temps you may get. I also deep littered their coop.