How do I refinish hardwood floors?

Refinishing a hardwood floor means sanding off the old finish, cleaning up every speck of dust, and putting on a new one. Bona, a maker of floor finishes, describes it as the most intensive option because it "completely removes the existing layer of finish before a new layer is added."^[2] A careful homeowner can do it. It is also unforgiving, so read the sections below before you rent a sander.

First, do you need to refinish at all

Many floors that look worn only need a recoat. Bona says a recoat "uses a buffer to lightly scuff the existing finish" to remove ground-in debris, and then another layer of finish goes on.^[2] It calls recoating "excellent preventative maintenance", and says refinishing is the answer for "moderate to severe damage" or a change of colour with a different stain.^[2]

Bona's own timing is overnight for a recoat and 2-4 days for a refinish.^[3] A floor does not need doing often: Bona says hardwood floors can be refinished every 7-10 years.^[1]

Check the floor can take it

Each sanding removes a layer of wood. Bona says a floor can be sanded around 4-6 times in its entire life, depending on its thickness and on the skill of whoever does the sanding.^[1] Engineered boards have only a thin hardwood layer on top, so if you cannot tell whether your floor is solid wood, have a flooring pro look at it before you sand.

Check for lead before you create dust

The EPA says "If your home was built before 1978, it may have lead-based paint; the older your home, the more likely it has lead-based paint."^[4] Sanding bare floorboards is not the same as sanding paint, but you will be working beside painted baseboards, door casings and thresholds. The EPA warns that any renovation project in a pre-1978 home with lead-based paint "can easily create dangerous lead dust", and it recommends hiring a lead-safe certified contractor for those projects.^[4] If you cannot determine the age of the home, the EPA says it is safest to assume lead-based paint is present.^[4]

Set up the room

Treat the room as a dust-containment zone. The EPA's do-it-yourself guidance is to remove furniture, area rugs and curtains, close and seal all doors in the work area, and turn off forced-air heating and air conditioning, then cover the vents with plastic sheeting and tape.^[4] Wear a respirator and eye protection, and wash your hands and face when you stop.^[4]

Bona warns that "not all dust containment systems are created equal."^[1] Rent a sander with an attached dust collector if you can, and do not count on one to catch everything.

Temperature matters for the finish. Bona says to keep the house consistent, with 65-75 degrees preferred, during the job and through the cure time.^[1]

Sand, then clean

Sand the main floor with the grain, using a drum or orbital floor sander and moving steadily. Bona warns that "oversanding can damage wood floors", and a sander left running in one spot will gouge a floor within seconds.^[1] Start with a coarser abrasive only as far as you need to remove the finish, then move to finer ones. Do the edges with an edger or a hand block, and fill nail holes and small gaps before the last pass.

Then clean as if the finish depends on it, because it does. The EPA recommends a HEPA vacuum on surfaces, followed by wiping with wet disposable cleaning cloths until the cloths come up clean.^[4] Dust left on the wood shows up as grit in the new finish.

Stain, seal, finish and cure

Test any stain on a hidden spot or a scrap first, since colour varies with the species. Apply stain, sealer and finish as the label directs, including the spread rate, drying time, number of coats and whether to buff between them. Ventilate, and dispose of rags as the label says.

Leave the floor alone for the full cure time on the label. The finish is usually dry to the touch long before it is hard, and furniture dragged back too early leaves marks that need another recoat to fix.

Stop and call a pro if

• The house was built before 1978 and the work will disturb painted surfaces. The EPA recommends homeowners hire a lead-safe certified contractor for these projects.^[4]
• You rent out part of the home or are fixing it to sell. The EPA says the lead rule generally does not apply to homeowners working in their own home, but it does apply if you rent all or part of the home or buy, renovate and sell homes for profit.^[4]
• The boards are cupped, buckled or stained from water. Some boards may need replacing, and the leak must be fixed first; see whether to refinish or replace hardwood floors.
• The floor bounces, sags or squeaks badly. That points to the subfloor or framing, which is not a refinishing job.
• You are not sure there is enough wood left to sand. A mistake cannot be undone.

Getting help in Virginia

Refinishing does not need a building permit: the Uniform Statewide Building Code lists "Installation or replacement of floor finishes in all occupancies." among the ordinary repairs that do not require a permit application.^[5] If you hire out the work, the Board for Contractors says a Virginia contractor's licence is required when the work is valued at $1,000 or more.^[6] Read how much hardwood floor refinishing costs in Virginia before you collect quotes, browse hardwood refinishing pros, or see more flooring answers.

When you are ready, describe your floors once and local flooring pros quote it.