I was thinking of buying a new dog house, there’s a great one on the internet, beautiful design, insulation, even windows, unfortunately it costs like hell and it’s 100 miles away, so I’d have to pay for transport as well and I’m out of money at the moment, so I was thinking of building my own alternative dog house from just wood, but thick enough to prevent losing too much heat.
The walls on the dog house I was looking at are made from 1mm OSB board on the inside, followed by a 3mm styrofoam layer and a wood layer on the outside of the walls, but I don’t know how thick that layer is.
So, if I used only wood, how thick would it have to be in order to have similar insulation characteristics? If it’s hard to calculate, what would at least be a good thickness for a dog house that would be used in winter?
To calculate insulation efficiency look up the R-value of the particular wood you want to use. Wood is not a great insulation material. The styrofoam sheets are dirt cheap and much more efficient. You could probably pick up scrap sheets from a construction site.
I built “The Best Cat House in Idaho” for my barn cats. It is made of a 1/2’ plywood case, with 1" styrofoam on the inside, and cedar siding on the outside. It has 2 levels in an effort to keep the heat in. The lower level has the entrance, and the upper level has an electric heating pad.
Without a door, the insulation of the dog house isn’t that crucial, as cold air will be constantly entering.
Is there a reason you’re considering using all wood? As steatopygia mentioned, wood isn’t a great insulator. There’s a reason that houses are built with insulating material in the walls: it’s much cheaper and easier to achieve a desired insulation level with insulating material rather than wood.
Also, your question “what would at least be a good thickness for a dog house that would be used in winter?” can’t be answered unless you tell us where you are. A good thickness for winter in Los Angeles is not going to be good for a winter in Minnesota.
5cms Styrofoam sandwiched between layers of 4mm ply would give sufficient insulation. A few coats of polyurethane varnish will make it waterproof and look okay. If you have some shingles about; put them on the roof for decoration. It’s important to insulate the floor and give the pooch somewhere inside to curl up in.
To put some numbers on this, rigid polystyrene insulation like this has an R value of 5.0 per inch. By contrast, solid pine has an R value of about 1.4 per inch. To match the 5 cm styrofoam that bob++ suggests, you’d need 18 cm (6.7 inches) of solid pine.
I built a heated cat house 15 years ago. It still works perfectly.
It was simple to build:
Using 2X4s, build a cube.
Screw plywood to bottom.
Screw plywood to the four sides.
Heavily insulate bottom and all sides by gluing thick (at least 1.5 inch) insulation foam to the plywood on the inside.
You don’t want your dog chewing on insulation, so you should also glue plywood to the foam on the inside. At this point, the outside and inside of the house are plywood, with foam sandwiched between.
Install a horizontal 2X4 in the middle, across the top. Mount and wire up two light bulb sockets on the top of the 2X4. Cut off the receptacle end of a 25 foot extension cord and connect it to the sockets. Screw in two heaters.
Build slanted roof rafters using 2X4s.
Install slanted roof using plywood. (Before screwing the plywood on, insulate the underside by gluing the foam insulation to it.)
That’s ridiculous design. Put a door on it. One easy design is a square of plywood door, with staples on either side onto bolts sticking out from the sides of the opening. Result is a swinging door that the dogs can use to go in & out at will. If you want it fancier, cover it on both sides with a scrap of carpet in whatever color you want. That can also help with heat retention.
Another option is two surface-mount bolts which slide into holes in the side walls – these work as well as the hing for the swinging door, but make it easy to remove the whole door for cleaning.
Growing up, we ran a boarding kennel with 15 individual runs for dogs, and each one had a swinging door like this. In western Minnesota winters, it was very important. And even dogs visiting for the first time figured out the door within the first day.