What Grit Sandpaper for Deck Sanding? 60-80 Grit, Then Stop

For a wood deck, sand with 60 to 80 grit and stop at 80. Strip old finish with 40 to 60 grit if it is thick, then make one final pass with 80. Going finer, the way you would on furniture, can close the wood pores and keep stain from soaking in.

That one rule is where most deck-sanding advice goes wrong. Furniture guides tell you to work up to 150 or 220 grit for a glass-smooth surface, and people carry that habit to the deck. Outdoor wood is different: the finish you apply next needs to soak in, not sit on a polished surface. Below is the grit sequence for each situation, what the stain makers say about it, and the safety steps people skip. For the work around sanding, see our guides on cleaning a wood deck and sealing a pressure treated deck.

Short Answer: 60 to 80 Grit, Then Stop

Think of deck sanding as two jobs. Job one is removing what is on the surface: old film-forming stain, paint, or loose gray fibers. That needs a coarse grit. Job two is leaving the wood open enough to take the new finish. That needs you to stop early. The sequence below comes from the surface-prep guidance of the stain makers and a deck-staining specialist site.

• Thick old stain, paint, or peeling film: 40 to 60 grit for the first pass, then 80 grit to even out the scratches.
• Weathered, gray, or lightly worn wood: 60 or 80 grit only. Ready Seal’s FAQ says to use 60 or 80 grit if you must sand, then clean the surface before staining.
• Raised grain between coats of a film-forming or solid color stain: a light pass with 120 grit or a fine sanding sponge, per DeckStainHelp. This is the only place 120 belongs on a deck.
• Never: 150, 180, or 220 grit as a “final smoothing” pass before a penetrating stain.

Why Finer Than 80 Grit Backfires on a Deck

Penetrating deck stains and oils work by soaking into the wood. Fine sandpaper burnishes and packs the surface fibers, so there is less open pore for the finish to enter. Ready Seal states that sanding can close the pores of the wood, making it harder for the stain to penetrate, and that you may only get one light coat of product to go in after sanding. DEFY’s Extreme data sheet is blunt about it too: if sanding is needed to remove older finishes, use a coarse grit, and avoid fine grit sandpaper because it can adversely affect penetration of the stain. DeckStainHelp puts a number on it: finish with 80 grit and never go finer, because finer sanding can cause premature stain failure within a year or two.

So the correction to the furniture habit is simple. On a deck, a slightly rougher surface is a feature. The scratch pattern from 80 grit disappears once stain goes on, and the wood stays receptive.

Grit Chart for Deck Sanding

How to Sand a Deck, Step by Step

• Clean and dry first. Remove dirt and mildew with a deck cleaner (see our DIY deck cleaner guide) and let the boards dry fully. Sandpaper clogs fast on damp wood.
• Set any raised nails or screws. A protruding screw head tears discs and can gouge the board.
• Start with the coarsest grit the job needs. Use 40-60 only if there is real film to remove. Otherwise start at 60 or 80.
• Sand with the grain. Cross-grain scratches show through stain. Keep the sander flat and moving.
• Finish at 80 and stop. Do not keep going to a finer grit because the wood feels rough.
• Vacuum, then wipe or rinse the dust off. Ready Seal recommends cleaning after sanding, and notes a light bleach-water solution can help reopen the pores. Let it dry before staining.

Boards, Rails, and Stairs

Flat deck boards are the place for a random orbit sander with 60 or 80 grit discs. Rails, balusters, and board edges are better hand sanded with a sanding block, since a power sander rounds over crisp edges and can dig into spindles. The same 80 grit ceiling applies to all of them. Handrails are touched constantly, so it is tempting to go finer, but a rail sanded too smooth will take less finish and wear through sooner.

Safety: Dust, Lead Paint, and Oily Rags

Lead paint. The federal government banned lead-based paint for homes in 1978. The EPA states that renovation, repair, or painting in a pre-1978 home can easily create dangerous lead dust, and that anyone paid to disturb painted surfaces in those homes must be certified in lead-safe work practices. If your deck, railing, or stairs have old paint and the house predates 1978, test the paint before you sand, and do not dry sand suspect paint.

Fire risk from oil stains. Cabot’s data sheet warns that rags, steel wool, and sanding residue soaked with its oil stain may spontaneously catch fire if improperly discarded. If you are sanding off an old oil-based finish, put the dust and rags in a sealed, water-filled metal container rather than a trash bag.

Dust. Wear eye protection and a respirator or tightly fitting dust mask, and use a sander with dust collection. The 8 holes in discs like the one above line up with the sander’s dust ports.

After Sanding: What Comes Next

Sanding is only the middle of the job. Clean off the dust, let the wood dry, and apply your finish while the surface is open. If your deck is new pressure treated lumber, timing matters more than grit, and our guide to sealing a pressure treated deck covers when and what to apply. The same lead-dust cautions for older paint apply indoors too, as covered in our guide to refinishing wood floors.

Frequently Asked Questions

What grit sandpaper should I use for deck sanding?

Use 40 to 60 grit to strip thick old finish, then finish with 80 grit. For bare weathered wood, 60 or 80 grit is enough. Do not sand finer than 80 grit before a penetrating stain.

Can I use 120 grit on a deck?

Only for a light pass between coats of a solid or film-forming stain to knock down raised grain. Before a penetrating stain or oil, stay at 80 grit or coarser.

Is 40 grit too coarse for a deck?

Not if you are removing thick stain or paint. Use it only as a first pass, then follow with 60 or 80 grit to remove the deeper scratches.

Why can sanding a deck too fine ruin the stain?

Fine sandpaper can close the wood pores, so penetrating stain has less open wood to soak into. Ready Seal and DEFY both warn about this in their guidance.

Do I need to sand a new pressure treated deck?

Often not. Clean the deck and let it dry, then follow the stain maker’s instructions. If you do sand, use 60 or 80 grit, never finer.