So, gluing the wood to the subflooring is suggested as well as nailing (toe nailing)? Before beginning the flooring, I will be leveling the floor using three 2×10’s face nailed and supported on 6×6 posts. I’m thinking of a 6×6 every 10 feet (floor is about 30×30 with a beam at 15′). Undercoat? as in coat the down side of the boards before installing? Please explain? You don’t advocate what? flooring without T&G?
No, I meant glue and toe nail just to hold the board in place while you then proceed to screw and peg the board. You’ve got to use wedges and even buy a Scrooge Clamp at :
You are really going to have to wrestle the boards tight. Don’t forget the drill kit and snug plugs at Lee Valley, really remarkable stuff, the best in North America. The snug plugs cut from the same boards make the pegs look quite natural. Hardly even notice them. And the Spax screws are a wonder, I use no others, I’m not kidding, and Mr. Lee does not pay me to say this. Although, if you like his products, let him know about us.
I’m not really concerned with the structure of your floor just have an unbroken PLYWOOD subfloor of at least 1″ thick, urethane glued to the joists, so that the waterproof plywood won’t allow moisture from under the floor to warp the wood floor.
Coat the underside of your milled planks with at least one coat of oil based polyurethane. Let it cure for a least a week.
Without the T&G, when you do have some great variances in indoor RH, the floor boards will surely cup or crown. With a T&G, the edges are held down by each other preventing or minimizing the warping. It’s the modern thing to do. And while your friend might have gotten away with it on narrow 4″ boards, the wider the plank the more the warp. Be sure to have a look and my sanding article, and especially my poly w/o bubbles article. You must you oil based here, but this is a different subject.
As always your Most humble servant, Joseph, the Wood Floor Doctor.