I think 16" o/c would be fine for oak planks. 16" o/c for treated pine 1-1/4" works and oak is a lot stronger. I've never seen it done but I'd bet they'd last quite a while considering how long oak barn siding lasts. If they were sealed regularly I'd bet oak would outlast unsealed treated. At that price I'd use the oak.



"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking