boxes for porch posts
my porch roof is supported by pressure-treated 4×4’s on elevated post holders, and I’d like to enclose the posts with ventilated boxes, with the boxes sitting on vinyl-composite bases. Any tips/pitfalls in building the boxes? How much gap between the 4×4 and the box, and how best to maintain the gap (PT shims? steel washers?)
Whatever you use to form the framework for the box just needs to have holes drilled in it or dados run through to allow some airflow. Keep the bottom and top open.
To me, those are the rules more than a specific opening. I would concentrate on getting the right proportions for looks and design, then work backwards to what size of gap to leave inside.
You may want to put some hardware cloth and or screen to block the openings to keep out bees and critters.
I'd prime everything on all sides too.
I think this was the FHB cover article within the last 2 or 3 years. Or at least a 3 page article with a pretty complete how to.