Hardwood Floor Repair: Tips & Tricks
At Creek & Hollow Hardwood, we believe in the importance of educating our clients on how to best maintain your hardwood flooring, so that your investment will continue to be a beautiful part of your home for years to come. We encourage you to explore these common problems compiled by the National Wood Flooring Association so that you can begin taking preventative measures to avoid having to perform a hardwood floor repair in the future. Each common problem includes a definition, a list of causes, and repair tips.
Buckling is excessive expansion that makes the wood flooring release from the subfloor.
- Moisture caused by excessive job-site moisture (airborne, subfloor, or flooding), a house left vacant with inadequate or no operating HVAC, grade conditions, a wet slab, or excessive humidity
- Additional exacerbating causes include: inadequate nailing, incorrect fasteners, or incorrect subfloor construction (for nail-down products), incorrect or insufficient adhesive, the wrong trowel size, inadequate adhesive transfer, subfloor separation, improper subfloor preparation, or subfloor contamination
- Inadequate expansion space
Rectify the elevated moisture situation (including by use of dehumidifiers) and let the floor and subfloor dry to normal levels. Release stress on the floor by providing relief at all vertical obstructions (walls, cabinets, etc.) and potentially remove a row of flooring. If handled in time, spot hardwood floor repair or replacement may be viable. In many situations, total replacement is necessary.
Crowning is when the center of the pieces of flooring appears to be higher than the edges.
Although it is possible that excess moisture could be the culprit, it is usually that the floor previously cupped and was sanded before the moisture content had a chance to return to normal levels. Sanding too quickly removed the raised edges. When the boards eventually dried, their edges where actually lower than the center.
Excessive drying from underneath can create a moisture imbalance that results in crowning.
First, ascertain if the moisture content in the subfloor and floor has stabilized and returned to normal levels. Also, establish if all of the crowning from the original cupped condition has occurred. After the floor has stabilized, resand and refinish.
Cupping occurs across the width of the individual pieces of flooring. The edges are high, whereas the center is lower. This condition typically develops over time.
- A moisture differential within individual pieces of flooring – often excess moisture on the underside of the flooring.
- Additional subtle cupping can be caused by lack of proper acclimation (which is usually permanent cupping).
- Possible culprits for excess moisture include: building leaks, poor drainage, plumbing leaks or overflows, leaks from dishwashers or refrigerator icemaking units, wet or damp basements/crawlspaces, concrete subfloors with excess moisture, poor or no ventilation, or HVAC system not operating
- Solid flooring also may cup when a wood floor undergoes conditions which trigger rapid drying on the surface. This occurs with gaps as the flooring shrinks.
- Low humidity levels can create cupping in engineered flooring which is often referred to as “dry cupping.” With dry cupping, the wood in the top layer attempts to shrink across its face while the shrinkage of the plywood backer is happening in much less of a surface area. (Dry cupping also occurs in tandem with “face-checking” – cracks in the board faces.)
Do not try to repair a cupped floor until all of the sources of excess moisture have been found and eliminated. This can only be proven with a moisture meter which takes readings of the subfloor underneath. As long as the wood is not permanently misshapen or damaged, the flooring should return to its initial shape and size once the excess moisture is eliminated. This may take weeks, months, or even an entire heating season.
Trying to sand a cupped floor while it is still moist may create additional cupping once the floor dries. Flooring which does not go back to its previous shape, even after an entire heating season, is likely permanently misshapen.
For flooring that has cupped from drying, relative humidity should be increased. Relative humidity below 20 percent is considered extremely dry for wood flooring; the best solution is adding humidification.
Face-checking is long cracks in the veneer which run down the length of the board in engineered flooring.
It usually happens when flooring is manufactured with an MC that is incompatible with the environmental conditions at the installation site.
Correct the humidity levels and follow appropriate maintenance procedures. Fill gaps as necessary and sand, fill, and refinish the floor if necessary (this may not always restore the original look of the floor). In some cases, certain boards (or possibly the entire floor) may need to be replaced.
This refers to gaps in the floor that remain with seasonal change. If some boards appear glued together by the finish on the surface, see Sidebonding.
- Edge crush/compression set from prior exposure to extreme moisture (especially for solid, flat-grained flooring)
- Hot spots in the subfloor, such as poorly insulated heating ducts, hot water plumbing lines, radiant heating systems, register openings, and appliance motors
- Debris between boards during installation
- Improper nailing/nail position
- Cracked tongues
- Flooring installed with an excessively high moisture content or over a subfloor with excessive moisture
- Flooring not installed tightly together to begin with
- Foundation settlement or subfloor movement
- Improper subfloor materials that will not hold nails
- For glue-down floors: early foot traffic, incorrect adhesive, the wrong amount of adhesive transferred or used, the wrong amount of flash time for the adhesive, or not using a roller when recommended
Eliminate the cause, then restore normal humidity levels. After the floor has stabilized, use filler in gaps that are small enough to be filled (typically up to 3⁄32 inch) and recoat the floor. For larger gaps, use a sliver/“Dutchman” or wider board to fill in the gap.
Gaps that appear between individual boards and open and close with changes in humidity.
- Most normal gaps are caused by seasonal fluctuations in relative humidity—the floor expands with high humidity and contracts during periods of low humidity. This type of expansion and contraction is considered to be normal and expected for wood floors. Wider boards have even wider gaps.
- Square-edged floors show gaps more than beveled floors, and light-colored floors show gaps more than dark floors.
Normal gaps can be minimized by using the HVAC system to control fluctuations in humidity in the building. The use of humidifiers and/or dehumidifiers can narrow the overall range of humidity fluctuation and aid in the hardwood floor repair process.
Unhappiness with the floor due to the appearance (i.e., knots, grain pattern, color variation, etc.)
- Unrealistic customer expectations
- Ordering mistake by supplier, distributor, or installer
- Poor grading at the mill
- Improperly labeled product
Replacing the offensive boards may be necessary.
Squeaky/Loose Floors (“Popping”)
Objectionable squeaks or other noises
- Movement of the wood flooring system, subfloor system, or underfloor supports
- Improper joist spacing
- Inadequate or improper nailing
- Weak subfloor
- Improper subfloor materials (thickness and/or type)
- Insufficient or incorrect adhesive
- Floor subjected to excessive moisture or excessively dry conditions
- Mismilled flooring
- Old age of the floor
Noises in only certain areas may be fixed by injecting adhesive into the problem area, screwing the floor down from below, or strengthening the subfloor from below. For floors that are noisy and loose throughout, the cause must be identified and resolved.
A generally uniform appearance of gaps in the surfaces of the floor that represents the size of the subfloor panel beneath it.
Excessive movement, shrinkage, or expansion of subfloor panels
Issues related to the subfloor must be resolved; typically this is not the responsibility of the flooring contractor. Then, repair the wood floor as necessary.
With sidebonding, the edges of the individual boards are “glued” together by the finish. It can occur with all types of finish, although it happens more frequently with water-based products. (Panelization and sidebonding may appear similar but are different problems.)
- Sidebonding results from the finish seeping down into the spaces between boards and gluing the boards together. It is usually noticeable only after a drastic decrease in humidity.
Restoring normal humidity levels may return the floor to an acceptable appearance. If there are still gaps, see the Cure for Gaps (Abnormal).
Staining or sealing floors with a specifically designed sealer may reduce sidebonding. Consult your finish manufacturer for other preventive steps.