|The following instructions apply to strip flooring laid on plywood-on-slab, on screeds, and plywood or board subfloors.
(NOTE: Flooring “SHORTS” – 1 1/4′ or 2′ bundles of flooring strips are “Strip Flooring” and should be installed as such.)
NOFMA does not recommend gluing Shorts directly to a slab.
With plywood or board subfloors, start by re-nailing any loose areas and sweeping the subfloor clean. Mark location of joists on perimeter walls so that starting runs and finishing runs, which require face nailing, can be nailed into joists. Then cover subfloor with a good grade of 15 lb. asphalt felt/building paper, lapped 2″-4″ along the edge seams. This helps keep out dust, retards moisture movement from below, and helps prevent squeaks in dry seasons.
Direction of finish flooring. Direction of finish flooring should be at right angles to the joists as shown in Fig. 4. This is generally the longest dimension of the room or building and gives best appearance.
Begin flooring installation along the longest continuous wall parallel to the flooring direction of most rooms. (i.e. Down a long hallway wall.) Work from there into the room. Use a slip-tongue to reverse direction and complete the rooms. Glue and blind nail the slip tongue. At any change of direction, always provide tongue and groove engagement either with a slip tongue, or factory edge or end.
Starting to lay the floor. Location and straight alignment of the first course is important. Place a mark 3/4″ plus the width of flooring (3″ for 2 1/4″ flooring) on the end wall near a corner of starting wall. (Figure 5.) Place similar mark at opposite corner and insert nails into each mark. Pull string line between nails. Nail the first strip with its leading edge on this line.
The gap between that strip and the wall is needed for expansion space and will be hidden by the shoe mold (Fig. 1).
If you’re working with screeds on slab make the same measurements and stretch a line between nails. Remove line after you get the starter board in place.
Lay the first strip along the starting string line, tongue out, and drive 6d or 8d flooring nails or casing nails (galvanized or screw shank hold best) 1″ from the grooved edge. Nails should be driven into the top surface of strips and counter sunk (face nailing). Position nails over supporting joists, and near ends of strips or into each screed crossed. Keep the starter strip aligned with the string line. (Pre-drilling nail holes will prevent splits.) Also, blind nail starting strip through the tongue according to nailing schedule.
Rack the floor. Lay out seven or eight rows of flooring end to end in a staggered pattern with end joints at least 6″ apart. Find or cut pieces to fit within 1/2″ of the end wall. Watch your pattern for even distribution of long and short pieces and to avoid clusters of short boards (Fig. 6).
Nailing the floor.
With plywood on slab construction the face nails should be cut to slightly less than 1 1/2″. After the starter run fit each run of successive strips snug, groove-to-tongue. Blind nail through the tongue along the length of the strip according to the schedule shown in the nailing schedule table. Countersink all nails. After the second or third run is in place you can change from a hammer to a floor nailing machine which drives nails mechanically or pneumatically, and does not require additional countersinking. Various floor nailing machines use either a barbed cleat or staples, fed into the machine in clips. The nailing machine drives fasteners through the tongue of the flooring at the proper angle.
When using the floor nailing machine to fasten 3/4″ thick strip or plank flooring to plywood laid on a slab, be sure to use a 1 1/2″ cleat, not the usual 2″ cleat which may come out the back of the plywood and prevent nails from countersinking properly and tearing the vapor retarder. In all other applications the 2″ cleat is preferred.
Continue installing across the room, ending up on the far wall with the same 3/4″ expansion space as on the beginning wall. It may be necessary to rip a strip to fit. Avoid nailing into a subfloor joint. Position flooring strips so that they do not meet over subfloor joints. Blind nail by hand where the nailing machine can not be used. Face nail the last runs when unable to blind nail by hand. With 2 1/4″ strip face-nailing is required the last 2 or 3 runs and in a ripped piece of a strip if one has been used. Use an offset pry bar or lever device to tighten these last face nailed runs all at once before face-nailing.
Nailing to screeds. When nailing direct to screeds (no solid subfloor), nail at all screed intersections and to both screeds where a strip passes over a lapped screed joint. Since flooring ends are tongue and grooved, all end joints do not need to meet over screeds but end joints of adjacent rows should not break over the same void between screeds.
Some boards may not be straight. A large screwdriver, sharpened pry bar, or wedges can force such boards into position or pull two or three runs together.
Shoe molding. Nail this to the baseboard, not the flooring, after the entire floor is in place.
*ALWAYS FOLLOW MANUFACTURERS’ DIRECTIONS