My bride thinks that the Southeastern flying squirrels that are so abundant here in South Carolina are about the cutest things she has seen, outside of me, of course. Since I am retired and have some time to devote to the project, I consented to design and build her a squirrel house with the added feature of a Bird House Spy Cam so she could keep track of the little critters on our big screen TV.
The design blueprint is all in my head, but is simple enough to build because it has only a few critical points. I used a couple of standard construction grade 2x4's, but they were specially selected from among many at the home improvement store. Criteria for selection is no knots, no warp, and no splits, so I had to cycle through at least half a bundle of them to find that criteria. I could have saved time by spending a little more and going for some furniture grade stuff, but I liked the challenege. All of the wood for the house was fashioned from these two 2x4's except for a couple of pieces of scrap 2x6 treated board and a piece of composite decking that I used for the mounting bracket. I also used exterior 3/8" plywood for the chimney and the gables.
Step 1: The Mounting Bracket
Since the finished house is rather heavy, I fashioned a bracket custom made for the tree I chose for the house. The pieces that rest against the tree are curved in and are composite material so it will resist rot, and the top and bottom cross members are 1" thick treated boards that will slide into slots in the house. The house will be attached to the bracket by two 1/4"x2" lag bolts at the top and two 2 1/2" wood screws at the bottom for adjustment to a level position should the tree be off from vertical.
Step 2: The Lower Section
I used a table saw to cut the 2x4 into 1" square "logs". I cut about 3 dozen of them 1' long even though I knew some would be 10" because of the "log cabin" type of construction. I chose this design because I read that these tiny creatures look for a stable and solid place for their nest and interlocked 1" square "logs" provide that stability. The logs are held together by three nails spaced evenly and a longer nail at the joints at the corners. A liberal amount of wood glue adds strength as well as a tight closure against the wind and rain.
I chose to provide the house with two shelves on the inside in addition to the floor so the squirrel with have options for the location for her nest, but would none the less be more likely to put it within view of the Spy Cam. The planks for the shelves were cut from the same 2x4 as were the logs and the dimensions were about the same for both except for the thickness which was about 1/8" for the planks.
The slots for the mounting bracket are formed at the bottom by the right ends of the two 1" crosswise logs and at the top by two short logs at the top of the right wall just under the bottom of the roof section.
The entrance hole is a piece of the 2x4 that is cut to 2"x8"x1" thick with a 1 1/2" hole at the center. This piece is also cut with a slot in the center of its thickness that will accept a piece of sheet metal to act as a deterrent for the big squirrels who will chew up the door to get inside. They do not want to live in there and they will not eat the smaller flying squirrel, so I guess they are just curious. It is much easier to place the metal with a couple of screws to hold it in place before you cut the entrance hole.
Step 3: The Roof Section
I also used the same planks cut for the shelves to fashion the rafters and ridge beam, but had to cut them longer. Every dimension in the construction is a derivative of the 1" square, 1 ' long logs of the walls, but notice that I made the roof 2" wider in the front/rear direction to provide for an overhang on the front. That overhang also creates a "loft" over the entrance hole.
The chimney is exterior plywood and is the location of the Spy Cam. I brought the cable for the Spy Cam in under the top plate of the chimney so that I could get to it easier without taking the house down. I used wood for the original top plate. but the big squirrels began to chew it up immediately, so I replaced it with a steel plate.
The gables are exterior plywood also and have an overlap to keep out water. The rubber gasket is the top of the slot for the mounting bracket and is also a water seal.
The roofing is cut from the original 2x4 and have about a 15 degree bevel for overlap, but you could use some other material to save time and trouble. I just liked the way the lap board roof looks, but if you use them be sure to use some wood glue along the edges between slats to keep out the rain. The peak of the roof is a strip of flashing folded over and stapled and glued to form a vent for the hot air in the Summer.
Finally, the roof section fit down over the lower house section so that one wood screw at each corner driven from the sides just under the roofing edge will hold the sections together. This will allow the roof section to be removed for cleaning without taking the house down.
Step 4: Finishing Up
The Spy Cam with a wide angle lens will give you a pretty good view of the interior, but your tenant could decide to nest under a shelf and if you try and change the Spy Cam to see him or her, they may desert you.
I buried the Spy Cam cable just about 4 or 5" in a slot in the turf of the backyard. I had to put the down wire from the squirrel house to ground in an armored conduit, however, because the big squirrels kept chewing it up.
The tree that we chose was leaning slightly, so I installed the house on the bracket using only the top two lag bolts and used them as pivots to tilt the house out until I had a center bubble on my spirit level and then installed the lower two wood screws.