A residence with a solid oak floor and a surface finish has been flooded

REMEDIAL ACTIONS
(1) Excess moisture from the flooded condition must be removed immediately. If cupping of flooring is the only adverse result, drying of the floor is necessary. The use of fans and dehumidifiers from the interior of the home or below the floor system (i.e. crawl space, if possible) may be all that is necessary to remove the cup. In homes with forced air heat, turn off any humidification and heat the residence to 76°- 80° F. Set furnace blower on manual to run continuously. After the flooring has flattened from the drying procedures, screening, filling, and re- coating could be sufficient for repair, if no permanent staining has occurred. If the floor is water stained, re-finishing may be necessary.

(2) If the water has been removed and cupping is prominent (buckling not present) light sanding directly across the grain of the flooring to remove the finish is required (this procedure should be done by a professional). Since the sanding drum follows the contour of the cup, flooring edges are not removed, which helps prevent crowning later. The sanding procedure allows the excess moisture in the flooring to dissipate faster. Do not sand the floor to bare wood, simply remove a majority of the finish. Drying of the floor as described in #1 should be initiated. After drying has occurred and the floor has stabilized and flattened, some compression cracks, some loose strips, and cracks due to movement from the initial flooding might be expected. At this time re-finishing may begin. Loose areas should be re-attached by nailing or screwing and cracks should be filled. This repair is a judgement call as the more severe the initial cause the more remedy #3 is indicated.

(3) If the floor has cupped and buckled, excess moisture probably remains in the flooring and floor system. Since the floor has also separated from the subfloor (buckled) and has loosened, replacement of the damaged and surrounding area is generally the procedure for repair. The excess moisture remaining in the underfloor system should be completely removed before re-installation and finishing. If the flooring is installed over plywood attached to a slab, removal of the entire system is normally required.

An attempt to cosmetically repair by simply re-nailing, sanding out the cup and re- finishing could backfire. Later problems with staining, crowning, cracks, finish failure, or loose floors could develop. By the time these later problems occur most insurance claim releases have been signed, and either the home owner or flooring contractor is saddled with the final repair. Additional repair, partial replacement and refinishing could be the least severe result. The worst case would be to completely replace the floor.

In any case quick action to remove the induced flooded moisture is the first step in successful repair. Patience is also required as finished flooring and floor systems do not react and dry out overnight. It may take weeks for the flooring to flatten and/or stabilize.

The above procedures would also apply to a sealed and waxed floor with the exception of not having to cross sand to remove finish. A sealed floor would also tend to dry quicker and in the least severe cases complete refinishing would not be required. Refurbishing or renovating with the appropriate cleaner and re-waxing can often restore a sealed and waxed floor's appearance.

REFERENCE: Additional pages
USDA - "Preventing Cracks" 
NOFMA - "Cupping & Crowning"
NOFMA - "Cracks in Hardwood Floors"

Reprinted from nofma.org web site