It is a moderately easy job to build a dog house for a large dog. You can do it in one weekend. If you use treated wood, your dog house should last for several years. The easy roof opening feature makes it simple to clean the house regularly.
Measure your dog from his nose to the back of his tail. This is the measurement for a snug, square dog house. Add 18 inches to that measurement to make a house that fits the dog. This project is based on 48 inches.
Translate the measurements for a 30 inch long dog into material measurements by adding 18 inches and building a square house. The floor and four sides are 48 inches square. Have the lumber company cut six pieces of finished ¾" plywood.
Screw together four 2x4x48 inch cedar studs to form a floor frame. Place a drop of wood glue in each screw hole to ensure a tighter fit. Repeat for the top frame.
Screw the frame to the floor section of the dog house. Butt the sides and screw three wall sections to the floor and roof frames. Cut a dog door the height of your dog's back plus 4 inches on the left 1/3 of the 4th wall and then screw it in place.
Use wood caulking to seal the four corner seams of the house.
Attach the roof section of the house to the frame with three hinges. This will allow you to fold the roof back to clean out the inside. Put two latch fixtures on the front side of the roof to lock it against wind and rain.
Finish the dog house with weatherproof stain. Use at least three coats. Allow the stain to dry thoroughly between coats.