Most solid hardwood floors can be refinished rather than replaced, often several times over their life. If the finish is dull and scratched but hasn't worn through to bare wood, a recoat (a light abrasion and a fresh coat of finish) may be all the floor needs. If there are deep scratches, gray worn-through traffic paths or stains, it needs a full sand and refinish. Replacement makes sense mainly when there isn't enough wood left above the tongue, when boards are rotted, badly water-damaged or structurally loose, or when the floor is engineered with a wear layer too thin to sand. In a house built before 1978, plan for lead before anyone sands.
This is general information. Most of the technical guidance below comes from articles by the technical staff of the National Wood Flooring Association (NWFA), published in its magazine, Hardwood Floors.
Three options, from least to most work
Recoat (also called screen and recoat, or buff and coat). The existing finish is cleaned, lightly abraded and given a new top coat. Very little wood is removed. According to the NWFA's guide to recoating a previously finished floor, recoating suits floors that don't have deep gouges and where the finish hasn't completely worn through. It won't change the color, and it won't remove scratches that go into the wood.
Full sand and refinish. The floor is sanded down to bare wood, then stained if you want a new color, and finished. The NWFA article on how many times a wood floor can be sanded says a traditional sand job removes about 1/32" to 1/16" of wood. Most solid wood floors can be sanded six to eight times over their service life, depending on the species, the wear layer, the floor's flatness and the skill of the person sanding.
Replace. Boards are patched in ("weaved in") where a section is damaged, or the whole floor is torn out and new flooring goes in. Patching with matching boards can be a good option when the damage is local, for example around an old radiator or where a wall was removed.
How to tell whether your floor can be sanded
Solid wood
Solid tongue-and-groove floors have a usable layer above the tongue. The same NWFA article says solid floors typically have a wear layer of around 1/4" or more. To see how much is left, pull a floor register or look at a board edge at a threshold or stair nosing. Signs the floor is near the end of its sanding life:
- the tongue or the groove is visible along board edges from above;
- nail heads show across the face of many boards;
- boards have been sanded so thin that they flex or crack.
A floor that has already been sanded many times, or sanded unevenly by an inexperienced operator, can have much less left in some spots than in others. Ask the contractor to check several areas, not just one.
Engineered wood
Engineered flooring has a thin layer of real wood on top of a plywood or composite core. The NWFA says that where the wear layer is less than 3/32" (2.38 mm), sanding is not recommended. If you know the brand and product, the manufacturer's specifications will list the wear layer. If not, a register opening or an edge at a transition usually shows it. A thin-veneer engineered floor can often still be recoated, as long as the finish hasn't worn through.
What's under the carpet
If you're pulling up carpet in an older rowhome or twin hoping to find wood, check what you actually have before planning a refinish. You may find solid wood in good shape, wood with a painted border around where a rug once sat, plywood or particleboard patches, or old resilient tile and adhesive. Paint on the floor matters for lead (see below). Old tile and its adhesive matter for asbestos: EPA's homeowner guidance on asbestos says not to sand or try to level asbestos flooring or its backing, and not to sand, scrape or drill materials that may contain asbestos. You can't tell by looking, so have suspect tile or adhesive tested before anyone grinds it off.
Can you just recoat? Test for wax and polish first
A recoat only works if the new coat bonds to what's already on the floor. The NWFA recoating guide describes simple tests in a high-traffic spot (not under a rug, in a closet or under furniture, where there's little buildup):
- Wax: rub a clean white rag dampened with mineral spirits on the floor. A slight yellow or brown color on the rag suggests paste wax. A few drops of water that leave white spots after about 10 minutes also suggest a waxed finish.
- Acrylic polish: put one or two drops of ammonia or acrylic polish stripper on an inconspicuous spot. Milky white spots after about two minutes suggest polish, which has to be fully removed first.
- Adhesion: for a professional recoat, the guide describes a small test patch of the new finish, followed by a cross-cut tape test once it has cured to see whether it pulls off. The test can damage the test area, so it belongs somewhere out of sight.
Waxed floors, or floors with years of "shine restorer" products, usually aren't good recoat candidates, and a full sand may be the only way to get a finish that sticks.
Why the season matters
Wood takes on moisture in humid weather and gives it up when the air is dry. In the Philadelphia area that means humid summers followed by dry air once the heat comes on. The NWFA article on seasonal floor problems says nearly every wood floor will show some seasonal separation between boards during the heating season, and that most of these gaps close up again when the heat goes off or humidity is added back. It warns against filling normal seasonal gaps: when the wood swells again, the filler can permanently damage the floor.
So if you see gaps between boards in January, that alone isn't a reason to replace a floor. Wait and see whether they close in summer. Gaps that stay open all year, cupped or crowned boards, or soft spots point to a moisture or subfloor problem, and that should be fixed before any refinishing.
If you refinish in the fall, you can usually still open windows for ventilation. If you're adding new boards or replacing a floor, ask the installer how they'll check the moisture content of the new wood and the subfloor, and how long the wood should sit in the house before installation. The flooring manufacturer's instructions usually set this.
Lead and dust in older homes
If your house was built before 1978, any paint on the floor, the stairs, the baseboards or the shoe molding may contain lead. Floor sanding also runs an edger right along the bottom of painted baseboards. Under the federal Renovation, Repair and Painting rule, a "painted surface" means a surface covered with "paint or other surface coatings," and a paid contractor who disturbs more than 6 square feet of painted surface per room generally has to be an EPA-certified firm and follow lead-safe work practices. Ask any contractor bidding on a pre-1978 floor whether they're EPA lead-safe certified, whether they'll test the floor finish, paint and trim, and how they'll contain and clean up the dust.
If you're doing the work yourself, the rule doesn't apply to you, but the dust is still a hazard. EPA has advice for homeowners doing their own renovation. Our post on lead paint in older Philadelphia homes covers testing and what certified work looks like.
Finishes and oily rags
Oil-based and water-based floor finishes differ in smell, drying time, color and how many coats are needed, so ask the contractor which product they plan to use and follow its recoat and cure times. Keep people and pets off the floor and furniture off it for as long as the product label says.
One safety point applies to any oil-based stain or finish. The National Fire Protection Association's safety tip sheet on oily rags explains that oils in oil-based paints and stains release heat as they dry, and a pile of rags can trap that heat and catch fire. The NFPA says this does not happen with water-based finishes. Its advice: never leave rags in a pile; spread or hang them outside to dry, away from buildings; then store them in a tightly covered metal container filled with water and detergent, and check with your town on disposal.
Do you need a permit?
L&I's building permit page says that, as long as a property isn't on the Philadelphia Historic Register, you often don't need a permit for repairs related to regular maintenance or for conventional floor coverings that aren't made of fibers. Refinishing an existing floor typically falls under maintenance. Replacing joists or subfloor, fixing a sagging floor, or removing walls is structural work and generally needs a permit. If the floor is on the historic register, or you're unsure, check with L&I. In Bucks and Montgomery counties, permits are handled by the township or borough.
A homeowner's checklist
- Find out when the house was built (property.phila.gov lists a year built in Philadelphia). If it's before 1978, plan for lead.
- Check whether the floor is solid or engineered, and how much wood is left above the tongue at a register or threshold.
- Note what's wrong: dull finish, scratches in the finish, scratches in the wood, gray worn paths, stains, gaps, cupping or soft spots.
- Do the wax and polish tests if you're hoping for a recoat.
- If you're uncovering wood under carpet or tile, look for painted borders and old tile or adhesive. Test suspect tile before removal.
- Fix any leaks, moisture or subfloor problems before refinishing.
- Decide on color and sheen, and whether you want oil-based or water-based finish.
- Plan where you'll stay or how you'll move around the house while rooms are off-limits.
When to call a pro
A recoat on a sound, unwaxed floor is something some homeowners do themselves. Call a flooring pro for a full sand, which takes a drum or belt sander and an edger, and is easy to gouge for someone without experience. Also call one when boards are loose, stained black from water or pet urine, or need patching. A pro is also the right call when the floor is engineered and you're not sure about the wear layer, or when the house is pre-1978 and the job will disturb paint. If the floor sags, bounces or slopes noticeably, have the framing looked at before anyone refinishes the surface.
When you get estimates, ask each pro whether they'd recoat, sand or replace, and why. Ask how much wood they think is left, how they'll handle dust and lead, which finish they'd use, and how long the rooms will be out of use. Our guide on how to check a contractor in Philadelphia covers the state registration and the written contract.
On HomeKept you can describe the floor once, with photos of the worn areas and a board edge, plus the year the house was built, and compare up to three estimates from local flooring pros in Philadelphia. It's free for homeowners.
HomeKept is a brand of FalconAI LLC, 331 E Street Rd, Feasterville-Trevose, PA 19053.
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