Not sure about where you are, but in our area, the law requires that outside dogs have a shelter that meets these criteria:
Minimum of 3 walls.
Solid roof overhead.
Floor raised off the ground beneath.
I.E., you cannot just provide a simple "lean to" for the dogs, or a bottomless "box" which shields them from above, but still makes them lay on the bare ground. We have 4 dogs (at least if you consider the chihuahua a dog... I think the jury is still out on that one), and 3 doghouses. 1 is a large home-built job which can easily accomodate two or three at a time, and the other two are the plastic doghouses you can get from WalMart for about $50. When I started figuring out how much it would cost me to buy wood to build a doghouse, plus the time, we decided the store bought ones were a better option (besides, the plastic roofs are easier to keep water proof than a wooden homebuilt roof).
We have a large back yard that the dogs have free run in. While two of the dogs are getting old and don't play much anymore (the one's idea of playing now is to take the toy and go lie down under the tree with it), our Australian Shepherd gets at least a few minutes of playing "fetch" whenever one of us goes into the back yard. If we're putting clothes on the line or something, he will keep dropping whichever toy he grabbed at our feet and looking at us, waiting for us to throw it, kick it, or whatever to send it flying across the yard for him to chase.
I can't imagine a home without a dog...