A corollary to NOFMA's Standard of Inspection for Wood Flooring: When viewed from a standing position, a repair should not be noticeable. It should be consistent with the rest of the flooring and have a uniform appearance.
Repair is critical to completing many jobs. The customer may have asked that an objectionable board be removed. Damage may have occurred from another source that needs repair before the invoice can be sent. Many other scenarios can pop up but the ultimate objective is to restore the floor and have the customer not be able to notice the restored area. At the NOFMA/ MFMA/NWFA Flooring School instructors demonstrate a single board repair on unfinished flooring as well as an area repair on previously stained solid wood flooring. During practice time, student participants gain hands-on experience doing the repair. For those who have not attended a Flooring School, we'll review the process here.
How to repair a site-finished wood floor
If the finishing has not yet begun, the repair is simplified. These repairs are normally associated with defective boards such as splits, bit ends, shake, deep gouges, etc.
Power tools needed: circular saw, miter saw, and vacuum. Hand tools needed: claw hammer, sharp 3/4-inch and 1/2-inch wood chisels, utility knife, nail puller (end nippers), nail set, pencil, block plane, flooring nailer and fasteners, epoxy glue and applicator. Safety equipment: ear plugs and safety glasses.
The procedure is to plainly mark the boards to be replaced. You don't want to turn a single board repair into an area repair. Set the circular saw depth of cut to the exact thickness of the flooring. Make two parallel cuts the length of the board 1/2-inch or so from the long edges and cross cut the center on an angle (take care not to cut into adjacent boards that do not need repair). Break the kerfs at the ends with the chisel and chisel through the cross cut.
Next select a replacement board that is similar to the surrounding flooring in color and grain pattern. Be sure it is the same species and near the moisture content of the existing flooring. Fit the piece in the open space on edge and mark with a utility knife for exact length. Cut to length on the miter saw. Cut off the bottom lip of the groove edge and groove end. Block plane the lower edge of the top groove lip on a slight angle. Trial fit into place, using the plane to better fit until the board almost fits home. The trail fit is very important for a snug fit with no gaps and to be able to tap the board home without damaging the surrounding boards. Apply the epoxy glue to the existing exposed tongue and into the groove of the opening in the flooring.
An area repair is similar but with multiple boards. With an area, you can usually blind nail some of the replacements and glue the last board. For a larger area, make a "story board" of the existing floor spacing using a straight piece of flooring by marking at each board intersections edge. Use this story board to position or locate each of the replacement boards so that the space for the last fitting board is not too narrow nor too wide.
Now comes the hard part. If the flooring has a finish and or stain, contractor experience becomes critical in the repair. Again, the objective is to make the repair blend with the surrounding flooring and not be noticed.
The following will illustrate the procedures for repair. These steps are not all-inclusive but will give the "flavor" for what is necessary.
The basic tools and items needed: a good set of eyes and hands, edger with proper grit paper (80, 100, 120), vacuum, broom, steel straight edge, sharp flooring scraper 3/4-inch to 11/2 inches wide, different grits of hand rub sanding paper (100, 120, 150, 180, 220), finishing materials (stain, finish, solvent, rags, brushes), safety equipment (respirator, ear plugs, gloves).
Apply color matched stain in the center of the sanded area and wipe from edge to center.
Previously sanding the finished edge with 800 or so automotive paper will slick the edge of the finish so stain can be completely wiped off and not create a halo. After the stain is dry degloss the finish around the perimeter and apply finish over the repaired area.