There are many various styles and materials used in wood dog houses.

You can find barn style, standard A-frame, or one with flatter roof in case your dog likes to lay on top of his house.  Single slant roof, Duplexes.  Some come with a hinged roof for easy cleaning.

A raised floor is available which would be warmer in the winter and cooler for the summer.  There are optional porches available, some open and some covered so your dog can lounge outside his door.

If you have more than one dog you might like to consider a duplex dog house where the inner panel is optional, allowing you to separate the dogs or let them bunk together.

Cedar is the most popular material for wood dog houses.  You will find some are constructed of fir also.  Wood dog houses are finished to withstand the weather,  of course cedar dog houses would weather nicely.  There are many finishes available if you choose another material.  Some people like their dog houses to match their house and that is also an option if you build a wood dog house yourself.