For roof decking, has anyone ever used dimensional lumber decking that is NOT tongue and groove? I know a lot of the homes on this site use the 2x6 T&G and it looks great, but I've checked prices and it is more than I want to spend on a roof deck. I saw that Vern Street made his own, but not sure I've got the time or tools for that.

The reason I'm asking is that I was at a restaurant last night, and on the wall, they had 1x6 rough sawn oak as a wainscoting. It wasn't tounge and groove, and i thought it looked really good. So I was wondering if that could be used for by exposed roof decking, if it were a little thicker.

A mill in the area quoted me a really good price on rough sawn red oak rafters....and I thought they might be able to do really well on some 1.5 inch thick oak planks for the exposed roof decking.

What do you think I would be missing by not going with T&G? Does the T&G add more rigidity mainly needed for flooring purposes? On top of the decking, I'm planning on 2x6s on edge, with 2x4 blocking to allow for ventilation, 4 inches of insulation, then a metal roof on top...might put OSB on top of the 2x6s. Snow load in Central Missouri is not really a big factor. Thanks.