Wide Board Flooring Tips

Advice on sawing, fastening and sanding wide board oak floors. September 15, 2006

I am currently milling up red and white oak for about 1000 square feet of flooring. The widths will vary from 4" to 11 1/2" inches. After having it dried to about 7 percent, I will mill it to 3/4" and utilize lap joint edge joinery. I am concerned about the movement of the boards after installation. I am considering screwing it through the subfloor and into the floor joists, countersinking the screws and applying matching oak caps over the screw heads, then planing the caps level and finally sanding the entire floor. Is this the best method to minimize movement? How far apart should I apply screws on wider boards? Should I use only one screw on narrower boards? Finally, I would like a clear or almost clear finish. What is the best product for this?

Forum Responses
(Sawing and Drying Forum)
From contributor R:
There was a guy who cut some wide boards 1/2'' thick and planed them down to 3/8'' and glued them down and from the pictures he showed, the floor looked like a good job after a year or so. I'd say you wouldn't need to plane the boards for flooring if you plan on using a floor sander.

From contributor D:
Leave the boards 3/4". Cutting them down to 1/2" will make them more likely to cup. Use a full trowel urethane adhesive like Bostic Best and you will have little to no movement. Screws would not be needed.

From contributor J:
I have always been told that you cannot glue solid wood to plywood because of the differences of how they move. Does gluing it down effectively seal the entire underside so it doesn't absorb any moisture?

From contributor T:
In the millwork industry, we never glue up panels with pieces over 7 inches because of the movement factor. We can expect callbacks if rule broken. Also, it is imperative that you rebate the backside of the flooring to relieve surface tension on bottom side. This is a must do! Gluing solid wood to plywood is okay as long as MC is 6 to 7%. Do not use a hard drying (brittle) glue on a floor, as it flexes as people walk around on it. Make sure plywood is dry before laminating flooring to it. MC in plywood can be too high in certain environments. Screws work/look nice with those plugs set and sanded flush. Especially contrasting wood such as walnut plugs on white oak, etc.

From contributor T:
After reading your post again, I must add: Don't let the lap joint be over 1/4" wide and keep the flooring 3/4 to 13/16 thick before sanding. Any more lap than that and that edge, the top lap, will curl up on you after you have the floor all finished. You don't want that! I've seen it before and it sure spoils a nice job.