Soft wood, had some splits and cracks in it so used wood glue and the screws ran into each other at the bottom of the catio where the caster mounts are and the frame. Had to drill pilot holes so the wood wouldn't split. The screws seemed on the short size.. Fortunately my husband the jack of all trades helped me out took us a few hours. His said it was ok for the $$$. He didn't have to build one! Elly Mae likes it and I am happy with it. But only time will tell..