What type of sheet goods should I use to build square exterior front porch columns?
Michael Dresdner: You want exterior structural sheathing, and there are many types, including exterior plywood, OSB, fiberboard, and several non-wood versions. I’m assuming you will be painting it, since all those need to be. You should be able to find most of them at the local home store. If the columns are load-bearing, you might want something more than simple sheet goods, though. Consider boxing in a support column so you are not relying on the plywood box for strength.
