Can you please repost the pictures of your shed.After much thought about what worked and what I wanted to improve over previous attempts, here is the latest version with a step by step pictorial on how I did it. It is time for my 2010 South African herd to move outside. They are moving into a 16x20' completely closed in enclosure. The enclosure is a wooden frame enclosed top to bottom with welded wire. It has a wire roof and the wire extends 18" down into the ground. The actual night box is 4x8x2'. I found a mini oil-filled heater to heat it with. The heater is on a thermostat and will be set to 80 for about half of the year and 70 over the warmer months.
Here is the lid. You can see the insulation in place.
Here is the plywood cover going over the insulation in the lid. The lid fits on top of the box and is hinged. There will be weatherstripping all around the top and the lip on the lid keeps the rain out of the box. You can see a finished lid for a second box in the background.
Here is the bottom. Notice the door notch and how that will fit in later.
Insulation in the bottom. All the insulation is 1.5" thick and has the shiny mylar foil side pointing to the outside. Don't know if that matters much, but thats how I did it.
Insulation on the floor all covered up.
Here the front and back are attached. Notice the door taking shape. Since 9 animals will initially share this, and as they get older they will get bigger, I went kinda big with the door at 26x16". This way one of them won't be able to sit in the doorway and block all the others in or out, and later, when they reach adult size, they will easily fit in and out of this door.
Another view of the front with the sides going up.
Here the side wall insulation is in place and about to be covered up. This box is also double caulked to keep out any cold drafts on those below freezing winter nights. The only air movement will be from the door, or when I open the lid.
All buttoned up.
Here goes the front insulation.
The front insulation is all covered up here. The 2x4 blocks there will support a 2x10" water tub holding shelf. Having containers of water inside will keep the humidity up in the night box, and act as a bit of a heat sink. This technique has been working very well in my underground sulcata night box.
Here's a top view showing the area where the heater will live, the weather stripping in place, the door flaps, and the 2x4 in the back that the lid hinges attach to.
Here is the front with paint and door flaps and water shelves in place.
Here is the door. I will carve out the dirt where the door/ramp hits the ground so it sits flush. One "weak" spot of previous designs was the simple plywood door. I went to great time and trouble to super insulate my night boxes, but then just used thin plywood to cover the door holes. This time the door shares the same 1.5" insulation as the rest of the box. Door open:
Here you can see the heater installed, the metal heat shield above it, the water tubs for humidity on the shelves, and my purple shoe box that holds all my electrical stuff.
Here are some of the babies enjoying their bermuda grass bedding.
Here is a wide view showing some of the enclosure. The empty wooden box in the lower right foreground of the pic is their 4x8' shade table/planter box. I will be filling it and planting leopard tortoise food in their in the next few days.
One more view of the same thing from the other side.
Well that's it. Tell me what you think.