I used regular plywood for both my coops. I built them early Spring of last year and they still look new. I put 3 coats of paint (just to be safe) all around the outside and edges and so far so good! We plan on building a small barn/large shed type of thing this Spring to house several types of chickens, and we plan on using plywood again...and lots of paint. We just have to repaint every so many years to keep it protected, but I don't mind doing this