With the start of the foundation that needs to be sound would usually be made of 2X6 lumber. This can be placed on top of the four posts that have been previously placed in the ground. It is best to have the chicken coop off the ground to help with ventilation and pest control.
Then each of the walls needs to be framed out. If you are strong and so is the help, some builders prefer to place the siding on before the wall is put up. I do not recommend this. The reason the frame is first completed is to make sure not only that the building is square but it is sound.
Once the frame is up and checked for being square the siding can be nailed in place. This is the part that will take time since this includes all the doors and hatches that have to be cut. If a storm is approaching or rain is predicted, the roof can be added after the frame is done to help protect the structure.
After all the sides and doors are in place it is time to paint. The prime and paint is essential for the building to last in the elements that Mother Nature will through at it over the years to come.
When complete the chickens can move in and as soon as the hens start laying eggs in their new nesting areas, I can have my farm fresh omelet. To build a chicken coop is fun and simple just make sure it has a solid foundation.