I’m installing an unfinished 1 X 4 T&G dougfir floor. Wood came from Canada and is beautiful, though very soft. Client was adamant about using df to match existing flooring so no choice there. Also wanted to keep the old and new flooring in the same plane so I’m forced to go directly to the old plank subfloor which is sound but far from level. Lot of planing and screwing down.
The wood was delivered in early January and was immediately “stuck” in the upstairs space in which it will be installed. There is propane forced-air heat throughout the building, keeping things at a toasty 50 degrees while the clients are away for the winter. This is Maine we’re talking about so still in the 20s outside.
Questions:
What should the moisture content be for installation?
Should I use #15 felt or rosin paper?
Given the softness of the wood, will a conventional pneumatic floor nailer (used cautiously) be okay in terms of not stoving things up? I plan on using 2 1/2″ Maze nails for any handnailing, followed by screwing/plugging, particularly around the splines.
Many thanks,
D.
Replies
Note that unvented propane heaters will have added a lot of moisture to the air.
basic stuff:
As a generic guideline, the moisture content of the wood should be within 4% of the MC of the subfloor for strip flooring 3" wide or less. For strip flooring wider than 3" it should be within 2% of the subfloor's MC. For Maine, another basic guideline is for the wood to be between 6% and 12% MC.
If this is not over a vented crawlspace where you might need a no-kidding VR with a perm of less than 1, and all you need is a vapor retarder in the 1-50 range, then #15 asphalt is fine. If it's over any sort of RFH, then use a non-asphalt product with the appropriate perm rating.
If the location doesn't warrant a vapor retarder and you simply want a slip sheet between the subfloor and strip flooring, then rosin paper is fine. If you're unsure of the need of rosin versus #15 felt, then use #15 felt.
Softwood strip flooring can still be toenailed through the tongue. You just need to fine tune the depth that the fasteners are driven by adjusting the compressor's air pressure or by making adjustments to the gun itself. Use a warped/crowned crappy closet-bound piece of strip flooring over the actual subfloor to test drive a couple of nails, adjust your equipment as needed, then retest over a few different spots on the subfloor. If the strips are custom milled with non-standard dimensions on the tongue, then you might need to shim the nail gun at the shoe to get proper nail placement on the tongue. Most nail guns come with shims for the shoe.
This is over a plank subfloor. For flatness of the plank subfloor, your goal would be for the floor to not be more than 1/4" out of flat over 10'. You can sand the highs and fill the lows as needed to ball park that figure.
The goal would be for the plank subfloor to already be installed at 45 degrees to the axis of the room, that way you can install the strip flooring in either direction. If the plank subfloor is installed along the long axis of the room and you want the strips to run parallel to the plank subfloor, your nails might find zero purchase along the subfloor joints.