I was called out to inspect a site-finished floor that had multiple concerns: white lines between the side joints and end joints, several areas where the finish was flaking, and areas where the finish had a cloudy appearance. The floor was made up of 3/4” x 4” solid, #1 common, plainsawn white oak, which was installed over 19/32” CDX plywood which was fastened to slab foundation. It had been distressed by handscraping across the grain, stained with a black stain, and finished with three coats of a two-component water base urethane.
Approximately 2,000 square feet of new wood flooring was installed as part of a water, mold, and termite remediation project. There was another 500 square feet of flooring that was originally installed many years ago and did not need to be replaced. The new oak was delivered to the jobsite in December of 2021 with the HVAC and humidification system running the entire time. The flooring was allowed to acclimate for approximately eight months due to various remodel delays. The flooring was installed and allowed to acclimate an additional two months while waiting for new cabinets to arrive.
The entire floor was sanded, scraped, stained, and finished in two separate phases, breaking it into two main areas so that the home could still be occupied during the process.
In the first phase, the floor was distressed by wetting the floor and scraping across the grain. The next morning the floor was stained with a black stain and then one coat of two-component water-based urethane was applied later that afternoon. The following day two additional coats of the same urethane finish were applied.
The day after the final coats were applied, the homeowner noticed a few white lines between some boards and inconsistent color in areas of the floor. The contractor attempted to address the concerns by applying two additional coats of finish. The problems got worse and resulted in a floor that had a cloudy appearance.
The second phase of the job was still to be done. The contractor was confident he could eliminate the same issues from occurring on the second phase by engaging the finish manufacturer to help with troubleshooting advice to avoid repeating the same mistakes. With guidance from the finish manufacturer, the contractor realized he should have used a sealer over the stain. He also assured the homeowner they would address the issues from the first phase.
For the second phase he followed the same process (except for the sealer step): he first wet the floor, then scraped the floor, and applied a black stain. He then applied a sealer coat later that same day. The following day he applied two more coats of the two-component finish.
Useful Tip From an Inspector:
As a professional installer, you are encouraged to read the directions on the products you are using in order to ensure success. Whether it is the tools and equipment you are using, the adhesives, sealers, finishes, or the stain, make sure you understand how they are designed to be used.
Upon completion the following day, the homeowner covered the floors with protective Ram Board and some drop cloths to protect it from potential damage from final trim and painting.
Approximately two weeks later the homeowner pulled back the Ram Board and drop-cloths and found the same white lines throughout the entire floor.
The white lines can be caused by finish coats being applied over stain that was not sufficiently dry. The white lines observed in these floors were likely the result of solvent from the stain not being allowed to dry completely before the finish coats were applied. The gaps between the boards and end joints allowed the stain to pool between the boards and in the torn grain. The stain between the boards and torn grain will skin over and appear to be dry, but the solvents below need additional drying time. Heavier pigmented stains take longer to dry than lighter pigmented stains. The stated dry time on the can is only a “best-case scenario” suggestion, and must be adjusted to accommodate the variables of the individual jobsite situation and the floor. When the homeowner covered the floors, the solvents remained trapped, resulting in an even more-severe scenario. Trapped solvents along with a build-up of multiple coats of finish can also result in a cloudy finished floor appearance.
There are several things that contributed to the finish failure in this floor. They include:
- The contractor stated, “They did not remove the excess stain from the floor.” All excess stain must be removed according to the stain manufacturer. The stain must be thoroughly dry before applying sealer or finish to the floor. Not removing excess stain or allowing the stain to dry thoroughly will cause the solvent to be trapped between the boards which results in white lines, chipping and flaking finish, and potential adhesion failure.
- The handscraping across the grain causes the grain to tear. Torn grain will take in more water and more stain than a smooth sand and finished floor. The stain that was used is a heavy pigmented stain, that will need a considerable amount of additional drying time.
- Covering the floor prior to the finish being fully cured will trap solvents and minimize the natural off-gassing process.
As a professional installer, you are encouraged to read the directions on the products you are using in order to ensure success. Whether it is the tools and equipment you are using, the adhesives, sealers, finishes, or the stain, make sure you understand how they are designed to be used. The homeowner must be aware of all of the requirements for protecting and maintaining the floors also. The manufacturers have tested, designed, and/or formulated their products to be used in specific ways.
Steve Moody is an NWFA Certified Wood Flooring Inspector and the owner of Steve Moody Inspections in Grapevine, Texas, and Flooring Inspirations LLC in Roanoke, Texas.