January, 2007
Inspection News and Views from the American Society of Home Inspectors

Walk the Plank


Quarter-sawn, flat-sawn, plank, thick veneer or thin veneer hardwood—wood floors of all types have been a mark of excellence in homes for years. Oak, maple, beech, pecan, Brazilian cherry, mahogany—you’ll see most, if not all, of these during your career as a home inspector. They can be installed with staples, square-cut nails, screw shanks, screws and staples and, in some instances, with adhesives. And, you’ll likely see them in
every possible condition.


Photo: Maple floor with 3 coats of oil urethane.

Photo courtesy of Don Lovering.

Even with this variation of wood, styles and installation methods, typical, readily discernible defects fall into one or more of six categories. Once I’ve identified defects, I use the guidelines following the list of common concerns to advise my clients on refinishing.


Photo: Oak floor with 2 coats of oil urethane.

Photo courtesy of Don Lovering.

1.  Particleboard Applications

When hardwood and softwood floors, both laminated and solid stock, are installed over particleboard, that is a readily observable defect. As an inspector, you will typically find this in a rehabilitated property because the owner/contractor has chosen not to remove the particleboard. The floor squeaks and the boards actually move under foot. I have found no practical way to repair this defect other than to tear up the floor, remove the particleboard and install proper sub-flooring, and then reinstall the hardwood flooring. The National Wood Flooring Association echoes this opinion.

2.  Moisture

Cupped floorboards indicate a moisture problem. The cupping can be pronounced with wide floorboards, including laminated flooring, or subtle with narrow floorboards. Wood flooring has a sealer on one side, leaving the remaining five sides open to absorbing moisture. All wood is hygroscopic (absorbs water), which causes it to expand when it gets wet and to shrink when it dries; it changes as its environment changes. In new construction, wood flooring is supposed to be allowed to acclimate to its environment for up to three weeks. This environment must be one in which the house has been completed, with walls, windows, roof, plaster, painting, plumbing in place, dewatering completed and the HVAC system operational.  

In my experience, most wood flooring is delivered and installed the same week, thus the frequent presence of cupping or other moisture-related defects.

Additional causes of moisture-related problems in wood floors include damp crawl spaces, wet basements, insufficient dehumidification, unvented clothes dryers, malfunctioning humidifiers, unvented bathroom fans and similar conditions.

Also, when the wood floor is fastened to the subfloor, the nails generally penetrate the underside of the subfloor, allowing moisture to wick and spread up to 12 inches around the fastener. The first step in rectifying this problem is to dry out the building and/or the basement/ crawlspace to get the moisture content of the flooring under 12 to 14 percent, as registered on a moisture  meter. This process can take several weeks with the HVAC system operating, plus a quality dehumidifier. Until the floor is dried out sufficiently, a complete evaluation and possible repair is next to impossible.

As an inspector, be alert for fasteners that have pulled free due to cupping and moisture-related issues. When walked on, the floor may actually creak and groan. In some cases, this noticeable defect can be addressed with a screw and plug method. One school of thought is that “minor cupping” once dried out will lay flat. Based on my training, education and experience, this is will not be the case.

3.  Wood flooring in basements and on slabs

Wood flooring installed in a basement or on a slab foundation requires substantial preparation that, in all likelihood, will not be visible to the inspector. If you suspect that the wood flooring is attached directly to the concrete floor, you should let your client know that the flooring may lift. This is true in both basement and slab environments, so when full solid-flooring is applied to plywood in the basement or on a slab, there needs to be at least a 3/4-inch gap around the perimeter between the flooring and the wall to allow for expansion. The gap is typically hidden by baseboard and a piece of quarter-round trim.

As you walk on the floor, the hollow sound of your footsteps will tell you that the floor probably is on sleepers. Sleepers are wood nailers, typically 2x3s or 2x4s, for the floor to be attached to. This is the preferred way to install a floor in this location, because the sleepers should create an air space between the concrete and plywood. If there isn’t a hollow sound as you walk across the floor, the floor may be attached directly to the concrete below.  

When laminates are applied, they, too, need a dry environment year-round. One industry standard is to have a 4 mil. plastic moisture barrier, free from holes and breaks, installed prior to installing the laminate boards.

4.  Prefinished Floors

Today, you can purchase a factory prefinished floor with a 25- and even a 50-year finish warranty in both full dimension and laminated material. Many of these are finished with an aluminum oxide finish. When scratches develop in these floors, a telephone call to the manufacturer or the wholesaler can provide you or your client with a factory-trained repairperson. The local floor refinishing company typically cannot field repair the defect.

5.  Lacquer

When the finish on the floor is peeling, typically it has had a base coat of lacquer, with an oil-based polyurethane applied over the top. The theory is that the lacquer provides a fast-setting first coat for the application of the polyurethane. Unfortunately, within two years the floor starts to peel, requiring a complete and correct refinishing. If you smell lacquer when you are inspecting new construction or a home where the floor is being refinished, get out of the building. Lacquer has a flash point well below room temperature.

6.  Water and Oil

When water-based or oil-based polyurethane is applied, three coats are the minimum prescribed by the National Wood Flooring Association. As an inspector, if you see pronounced wood grain when viewing the floor in natural light, you’ll know only two coats have been applied. This floor will need to be sanded and refinished after minimal foot traffic. The phrase “not installed to industry standards” comes into play.


Photo: 10-year-old oil urethane finish on oak.

Photo courtesy of Don Lovering.


Photo: 20-year-old oil urethane finish (3 coats) on oak.

Photo courtesy of Don Lovering.


Photo: 2-year-old sun-darkened finish on cherry.

Photo courtesy of Don Lovering.

When to Refinish

Much like everything else we do or say, advice on when to refinish a floor is given on a case-by-case basis. I use the following guidelines to make the call.

Rust Stains: These occur in the finish when the contractor used steel wool with a water-based finish. The floor needs to be completely refinished.

Water marks: These look like fish eyes or small blotches from the size of a pencil eraser to a quarter-sized spot. Commonplace if the floor was finished in the summer months, they occur when sweat dripped onto the finish. A spot repair, requiring sanding, will generally correct this issue.

Black Stains: Pet urine, water leaks and plant fertilizer are prime sources of these stains. The floor will need to be completely sanded and a SKILLED floor refinishing company brought in to bleach the entire floor area. Be aware that this is generally a one-time attempt; the floors in the room in question will be of a different color from the floors in the house that were not bleached. If there is large-scale black staining from water entry, the floor needs to be replaced and the water source repaired.

Cross-Cut: Noticeable around the edges of the room and in hallways, gouges and ring or half moon cuts are not acceptable. The floor needs to be sanded and completely refinished with three coats of sealer by an experienced floor company.

High-Traffic Areas: Worn areas in entries and hallways require sanding and three coats of finish. The finish is typically applied in one direction with a lambs wool mop.
Bubbles: You see an area or the whole floor that has a blistered, bubbled appearance; most noticeable in natural light. This can occur when the floor-finishing crew went in two directions while applying the finish. Sand the floors and refinish.

Laminated Flooring: Defects of any type in the finish are next to impossible to field repair. While there are some limited exceptions, err on the conservative side when reporting. The floor will need to be replaced.

Lifting Putty: To begin with, this looks like ketchup on a white shirt and it is not going to get any better. Several floor contractors I have met try to mix the flooring sawdust with glue and apply—with very mixed results.
Commercially available wood fillers tend to not match the floor color. If putty is to be used, the floor needs to be refinished to seal the entire floor area.

Penetrating Oils: This is a very good finish, but it is susceptible to chemical staining from liquor, and it is very difficult to re-blend with the existing floor color.

Wax: Wax should not be applied to oil-based or water-based sealers. If it has been applied, the floor will need to be refinished. The wax must be removed prior to the sanding process.

Exposed Nails: You will see this in an older dwelling that has wood floors without face nailing. The floors have been refinished more than four times. They need to be replaced.

Face Nailing: This is a common practice in older homes. Before refinishing, all the nails require setting below the surface to prevent shredding of the sanding drum. This is very labor-intensive.

Unlike the fine mirror furniture finish that we all have grown fond of and many clients expect, floor finishes do not end up that way. Variations exist. What is paramount is that throughout the entire area there is a uniform fit
and finish that is in conformity with minimum industry standards. Only knowledgeable and experienced floor mechanics should undertake repairs to areas that need attention.

Wood Flooring Resources

National Wood Flooring Association: www.nwfa.org and www.woodfloors.org

The Hardwood Council: www.hardwoodcouncil.com

Maple Flooring Manufacturers Association: www.mfma.com

Wood Flooring Manufacturers Association: www.nofma.org

Hardwood Manufacturers Association: www.hardwoodinfo.com