Floor Sanding
Sanding is the step of hardwood floor refinishing that takes off the old finish and evens the surface, and it is the step that takes wood off the floor. This page stays on sanding: what the sources say it involves, the grits manufacturers name for their own finishes, and how to judge whether a floor can take it. The hardwood floor refinishing page covers the whole sequence from the first cut to the last coat.
What sanding does
A wood-floor extension publication from Purdue and the U.S. Forest Service's Forest Products Laboratory, Finishing and Maintaining Wood Floors (1980), describes sanding in successive cuts from coarse to fine grit: two cuts, or three if the floor is uneven. It advises removing no more wood than absolutely necessary (USDA Forest Products Laboratory, 1980). NWFA says sanding a floor back to raw wood is the opportunity to change its color (NWFA, Refinishing Your Floors, as of 2026), which is covered under staining and color change.
Sanding is not the same as the lighter job of a recoat. NWFA describes a maintenance coat as cleaning the existing finish, lightly sanding it and applying a fresh coat, and Bona describes recoating as a buffer lightly scuffing the finish before a new coat goes on (NWFA and Bona, as of 2026). That lighter job is covered under screen and recoat.
The grits manufacturers name
No source read for this site gives one grit sequence that suits every floor, and none gives a starting grit. What manufacturers publish is the finest grit their own finish allows before it goes on, and a lighter abrasion between coats. A higher grit number means finer paper. The figures below are examples from named products, not general rules.
| Product | Before the first coat | Between coats, or on a recoat | Source |
|---|---|---|---|
| Bona Traffic HD (two-component waterborne finish) | Stained floor: final cut 80-100 grit, then a multidisc step at 80-120 grit. Unstained floor: final cut 80-120 grit, then a multidisc step at 120-150 grit | Not needed unless more than 48 hours have passed; then 180-240 grit | Bona data sheet, 05/27/2026 |
| Minwax Super Fast-Drying Polyurethane for Floors 350 V.O.C. (oil-based) | New floor to be stained or sealed: no higher than 100 grit. No stain or sealer: no higher than 120 grit. Previously finished floor in good condition (no chipping, peeling, worn areas or residue): lightly with 120 grit | If more than 10 hours pass before the next coat: lightly with 220 grit | Minwax data sheet, Rev. 1, 1/30/2026 |
| Minwax Ultra Fast-Drying Polyurethane for Floors (water-based, 275 V.O.C.) | The data sheet gives no sanding grits | If the next coat misses the stated window of at least 2 hours but less than 8 hours: lightly with 220 grit | Minwax data sheet, undated, read in 2026 |
| Bona recoat treatment (Bona's professional page) | Not applicable | Clean the floor, abrade with 240 grit, and apply the finish within 2 hours | Bona, as of 2026 |
Three points follow from the table. The limits belong to the finish, so a sanding plan has to be matched to the product that will go on. The sheets state the final or highest grit their finish allows, not a full sequence. And the between-coat figures are for a lighter abrasion, not a return to bare wood.
How many cuts
The only stage count in the sources is the 1980 USDA publication's: two cuts, or three when the floor is uneven. Beyond that, the sources give the final grit a product allows, not a full sequence, so this page does not list one. A quote that names grits should say which finish system they belong to.
Can this floor be sanded again?
Thickness is the first thing the sources point to. The 1980 USDA publication says most flooring is 3/4 inch thick, so it can withstand a number of sandings, and that a floor thinner than 3/4 inch or made of hardwood plywood needs care to prevent sanding through. It says the thickness can usually be found by removing a floor heating register, or the shoe mold and baseboard, so that an edge of the floor shows (USDA Forest Products Laboratory, 1980).
NWFA says solid wood flooring can be sanded and refinished many times, and that engineered wood flooring can be sanded and refinished but not as many times (NWFA, Types of Wood Floors, as of 2026). For engineered floors the deciding measure is the wear layer, the top layer of real wood. NWFA's Engineered Wood Flooring Refinishable Program certifies products with a minimum wear layer of 3.2 mm for unfinished floors, 2.5 mm for factory-finished floors, and 2.5 mm at the lowest point for sculpted or distressed floors. NWFA says the program was designed to identify engineered products with wear layers thick enough to be refinished (NWFA, 8.2023). Those are the criteria of a voluntary certification program, not a universal limit, and not a count of sandings.
How much wood comes off
NWFA says how many times a floor can be sanded depends on the contractor's skill, the equipment used, the thickness of the wear layer, the flatness of the floor and its condition, and its own consumer pages give no number (NWFA, as of 2026). NWFA's consumer outreach toolkit adds that a professional refinisher removes very little wood to make repairs, generally 1/32 inch or less, while someone without proper training or equipment might remove much more, which greatly reduces the life of the floor. It also says most wood floors can be sanded and refinished several times during their service lives (NWFA, Consumer Outreach Toolkit, uploaded 2020). That toolkit is written for NWFA's members, so it is NWFA's own statement rather than independent testing. No count of possible sandings appears on this site. NWFA's trade magazine has separately published a range in a different article, but this site does not use it, for the same reason it does not use Bona's marketing figure (see refinish or replace). Refinish or replace covers how to judge a floor.
Sanding and the finish that follows
The grit a floor is left at affects how the next product behaves, which is why the data sheets state limits. Water-based vs oil-based finish compares the two classes, and the restoration and repair page covers scratches, gaps and damaged boards that sanding alone does not fix.
Questions worth asking about sanding
- Which finish system will go on, and what final grit does its instructions allow?
- Was the thickness of the floor checked, and how?
- Is the floor solid or engineered, and if engineered, how thick is the wear layer?
- Is the job a full sand to bare wood, or a lighter abrasion before a recoat?
- Will the whole room be sanded, or only part of it?