How to Refinish Hardwood Floors?

Quick Answer

To refinish a hardwood floor, sand in three passes (36 grit, 60 grit, 100 grit) with a rented drum sander and matching edger, vacuum and tack-cloth between passes, then apply 3 coats of water-based polyurethane (or 2 coats of oil-modified) with a lambswool applicator. A 300 square foot room is a full weekend for a DIYer. Solid hardwood can be refinished 4 to 6 times over its life; engineered hardwood with a 3 mm or thicker wear layer once or twice.

Materials and rental run about $1.50 to $3 per square foot DIY versus $3 to $8 hired out (NWFA member quotes, 2026).

Before You Sand

• Confirm there is enough wood left. Pull a vent and measure from the top of the plank to the tongue. You need at least 1/16 inch above the tongue to sand safely.
• Set every nail with a nail set and punch below the surface or the drum will tear up.
• Tape off doorways with plastic sheeting. Sanding dust gets everywhere.
• Rent the right machines: drum sander for the field, edger for the perimeter, buffer for the final screen.

Step-by-Step

1. 36 grit pass. Strips finish and levels. Sand with the grain in slightly overlapping straight lines. Never stop the drum in one spot.
2. 60 grit pass. Removes the deep scratches from 36 grit.
3. 100 grit pass. Final smoothing. Floor should feel like fine paper to the hand.
4. Edger matches the field grits along walls and into corners.
5. Buff or screen with 120 grit on a buffer to blend the drum and edger marks.
6. Vacuum and tack. Every surface in the room. Skip this and the finish is bumpy.
7. Optional stain. Wipe on, wipe off after 5 to 10 minutes, dry 24 hours.
8. Polyurethane: 2 coats oil-based (24 hour recoat, amber tone) or 3 coats water-based (2 to 4 hour recoat, clear).
9. Cure 24 hours before light foot traffic, 7 days before rugs, 30 days before heavy furniture.

Common Mistakes

• Skipping a grit. 36 to 100 leaves scratches the finish will magnify.
• Stopping the drum. Creates a dished low spot you cannot sand out.
• Recoating too soon. Water-based needs full 2 hours minimum or layers wrinkle.
• Skipping the screen pass. Drum and edger leave a visible halo around the perimeter.

Frequently Asked Questions

What flatness does the subfloor need?

The industry default is 3/16 inch deviation over a 10 foot span (about 5 mm over 3 metres). Floating floors, rigid-core LVP, and engineered hardwood all share that spec. Tile is stricter at 1/8 inch over 10 feet because thinset cannot bridge a wavy slab.

How long should materials acclimate on site?

48 hours for laminate and LVP, 7 to 14 days for solid and engineered hardwood (until plank moisture content is within 2 to 4 percent of the subfloor). Skip it and you risk gapping in winter or cupping in summer.

Does this work over radiant heat?

Most rigid-core LVP, engineered hardwood, and porcelain tile are radiant-heat rated up to about 82F (28C) at the subfloor. Solid hardwood and bamboo usually are not. Always confirm the manufacturer spec before laying.

Is it the same in the UK?

The product categories and installation rules are nearly identical. UK retailers like B&Q, Wickes, Carpetright, and Topps Tiles carry the same Shaw / Mohawk / COREtec equivalents with British Standard labelling (BS EN 13329 for laminate, BS EN ISO 10874 for resilient flooring).

Pro Tips From the Trade

• Order 10 percent waste. Bump to 15 percent on diagonal layouts, herringbone, or rooms with lots of cutouts. Future repair planks need the same dye lot.
• Photograph the install. Subfloor, vapour barrier, expansion gaps, transitions. Warranty claims hinge on documentation.
• Keep one full carton. Same production run, stored flat in conditioned space. It is the only colour-true repair source you will ever have.
• Run planks toward the light. Parallel to the longest wall or toward the main window so seams disappear instead of catching shadows.
• Test moisture. Tape a 2 ft square of plastic to a concrete slab for 72 hours; condensation underneath means a moisture problem to solve before any flooring goes down.

Bottom Line

The product matters less than the prep. A flat, dry, clean subfloor with correct underlayment and proper acclimation will make a mid-priced floor outperform a premium one installed badly. Get those four basics right, follow the manufacturer's spec sheet, and you will not see a single one of the common failure modes (cupping, gapping, lifting, telegraphing) in the first decade.

Quick Buying Checklist

• Confirm the manufacturer's warranty covers your install path (residential vs commercial, DIY vs professional). Most warranties void automatically if you skip moisture testing, acclimation, or the specified underlayment.
• Order 10 to 15 percent extra from the same production lot. Future repair planks have to match the dye and texture exactly, and lot-to-lot variation is real even within a single brand.
• Match the underlayment to the product. The wrong foam (too thick, too soft, or wrong density) is the most common reason click joints fail in year two.
• Plan transitions early. Reducers, T-mouldings, stair nosings, and undercut door casings cost three times more if you order them after the install.
• Photograph the prep work. Subfloor, moisture readings, vapour barrier, expansion gaps. Most warranty claims get denied for lack of documentation.

Cross-reference the manufacturer's installation guide against the National Wood Flooring Association (NWFA) install best practices before you start. Mismatches happen, and the manufacturer guide wins for warranty purposes while the NWFA guide wins on long-term durability. When both agree, follow them to the letter and the floor will outlive its written warranty.