Had a porch surround built this summer so we could use the space all year round. The wall is framed double hung windows with a header and at the base int/ext is panelling made by our contractor. Unfortunately some of the panels have already begun to warp and the surrounding framing is popping out as a result. He used poplar to make the panels which apparently is a poor choice for exterior woodwork. What would have been a better option? I primed all sides and edges of the panels before installation and gave them two coats of SW Emerald-so coverage is not the issue.