After severe water damage hardwood floor replacement is nearly always necessary. Follow these steps to check the sub-floor below the hardwood floor for damage, repair and replace sections of the sub-floor as needed, and then replace the hardwood floor.
Step 1: Assess the Depth of Damage
Examine all the hardwood-floored rooms that were flooded. Places where the boards have popped up, split or cracked may indicate sub-floor damage. Go down to the basement and check the sub-floor and the main floor joists below your hardwood floor. If any of the sub-floor sections or joists are warped and damp, those sections will need to be replaced before you install new hardwood flooring. Installing new hardwood over a damaged sub-floor will cause the hardwood planks to lift, buckle and warp.
Step 2: Remove the Old Hardwood Flooring
Remove all the furniture from the room. Remove the baseboards to determine if the hardwood flooring goes under the wall. If so, you will need to cut the old hardwood planks at the wall edge. If you are removing parquet hardwood flooring, use a glue dissolver to melt off old glue stuck to the sub-floor.
Step 3: Repair the Sub-floor
Measure all the sub-floor sections that need replacing, and purchase sub-floor plywood or softwood planks larger than the damaged parts. Drill a hole through a the center of the damaged sub-floor section to gauge the sub-floor's thickness. Set the circular saw's cutting depth to that dimension, and cut away the damaged sub-floor completely. Cut the sub-floor sections to fit precisely with the circular saw. Nail the new sub-flooring sections directly to the floor joists with the framing nailer, attached to the air compressor.
Step 4: Replace the Hardwood Flooring
If you live in an area of high humidity, allow the new flooring to cure and adjust to the air moisture before you install it. Check the sub-floor thoroughly before you begin to install the hardwood. Look for nails or staples protruding from the sub-floor and sink them below the surface. If this room is over a concrete basement, lay down some acoustic underlay foam as a sound barrier. Start laying the hardwood planks at the straightest wall. Put a 1/4-inch spacer between the first plank and the wall to leave room for the baseboard. Snap a chalk line across the sub-floor to give a straight baseline for all the planks. Fasten the first plank to the sub-floor with its groove facing the wall, using finish nails. Nail down subsequent planks with the flooring nailer. Lay out the hardwood so plank ends are staggered at least 3 inches apart in adjoining rows. Reinstall the previous baseboards, or purchase new baseboard trim if the baseboards also suffered water damage.
Step 5: Let the Floor Settle
Allow the hardwood floor to settle for 24 hours, then replace furniture in the room.