I tried a couple of things to stop the freezing before writeing them.
One thing I found after writeing them is Hopps # 9 MDL sprayed on the zippers thru the straw.
Still the zippers could use the courser teeth and most of all a flap over them to protect them.
A sheet of the cedar T1-11 is $15.00, 4 needed
A sheet of OSB for the roof is $6.88 1 required.
a2x4 is $1.88 2 required split in half.
A small bit of sheet black plastic as a roofing materal. about $5.00
A hand full of dry wall screws Lets say $5.00
Comes to 85.64 for the stuff I need to buy.
I have windows I picked out of the trash I can cut down for that. Frames can be made from the left over OSB or T 1-11

Al