Our winters can be long and VERY cold (-40 is not un common) and lets face it , keeping the dogs housed properly can be a challenge when it gets that cold out... One alternative to building a wooden insulated house is to get ahold of a small deep freezer (It doesn't need to work as you'll be removing the motor anyways).
Some benefits of using the deepfreeze dog house are ,they are completely waterproof , it's already insulated , ** it has a hinged top thats sealed so you can open the lid when its time to change out their bedding or wash it when needed** , the only wood needed is to go inside the opening thats been cut in one of the ends so they dont cut themselves on any sharp edges etc..
These setups will last MANY years and are surprisingly light so one person can skid them around when you have to clean the yard etc..
Simply cut out an opening in one end , line the opening with some wood and add a flap to keep the wind out.
Seeing as you don't need a working freezer , they can usually be picked up for free , so the only cost is the material for the opening