[tmbrx]

I am building a small pergola over part of my patio; I live in suburban Detroit, so the structure will be exposed to all four seasons.
My plan is to finish the structure with an oil-based exterior primer and white paint.
My question concerns covering the wolmanized posts I've used as the uprights; what kind of material should I (or, should I NOT) use? Can I use MDF or a good grade of plywood (if I will be sanding and painting all of the exposed edges)? Must I use a 1-by pine?
I appreciate any advice that could be offered!

 

[Ron6519]

I am building a small pergola over part of my patio; I live in suburban Detroit, so the structure will be exposed to all four seasons.
My plan is to finish the structure with an oil-based exterior primer and white paint.
My question concerns covering the wolmanized posts I've used as the uprights; what kind of material should I (or, should I NOT) use? Can I use MDF or a good grade of plywood (if I will be sanding and painting all of the exposed edges)? Must I use a 1-by pine?
I appreciate any advice that could be offered!

MDF is not used outside in the weather. I'd avoid plywood as well.
I'd cap the posts with cedar. Seal the wood that is in contact with the ground/concrete. I would hold the capping off the ground by an inch and hide the gap with a wrap around base. The base could be a composite material that will not rot or a sealed cedar or PT wood.