How to Sand a Deck With a Sander

Get the deck ready first

Good prep saves belts and prevents damage to your sander. Sweep the deck, scrub off dirt and mildew, and let the wood dry fully before you sand. Damp wood clogs abrasives and sands unevenly.

Then walk every board and look for nail heads and screw heads. Hammer nails below the surface or drive screws down a little deeper. A raised fastener can tear a belt in one pass and can throw sparks or damage the sander.

Also move furniture, planters and grills off the deck, cover nearby plants, and close windows and vents near the work area. Old stain dust travels farther than you expect.

Pick the right sander for the job

For flat boards, a belt sander removes old finish and weathered wood faster than any other handheld option. Our best sander for sanding a deck page compares 3 x 21 in models, narrow detail belts and bandfiles on one spec sheet, so you can match the tool to your deck.

An orbital sander is a gentler option. It leaves fewer deep marks, which helps on a small deck or for a final smoothing pass, but it is slow on heavy stripping. Many people strip with a belt sander and finish with an orbital sander or hand sanding block.

Here is how the main tool types compare, using the published specs on our comparison page.

Sand the deck boards step by step

The method is the same for belt sanders and most deck sanders. Keep the tool moving and let the abrasive do the cutting instead of pressing down.

• Fit a coarse belt, often in the 40 to 60 grit range, for the first pass. Use a finer belt if the wood is already fairly clean.
• Set a low to moderate speed if your sander has a dial. Slower speeds lower the risk of gouging soft wood.
• Start the sander with the belt lifted off the wood, then lower it onto the board gradually while it is moving.
• Sand along the length of each board, with the grain, in smooth overlapping passes. Never sand across the grain.
• Lift the sander smoothly before you stop moving it, and switch it off with the belt clear of the wood.
• Move to an 80 grit belt to remove the scratches from the first pass, then finish with 100 to 120 grit.
• Check the surface after each grit. Sand until the old finish and grey wood are gone and the board looks evenly bare.

Handle railings, spindles and edges

Big sanders cannot reach into the gaps between boards or around balusters. This is where a 1/2 x 18 in detail belt sander or bandfile earns its place. These tools are light, so they are easier to control on vertical parts and tight corners. The deck sander comparison lists belt speeds and weights for several of them.

For handrails, round edges and anything else a machine would gouge, hand sanding is the safer choice. Wrap sandpaper around a sanding block or a small piece of scrap wood, and work with the grain. It is slower, but you control every stroke.

Wear gloves that fit well, and keep fingers clear of the belt on detail sanders. Hold the work steady so it cannot kick back toward you.

Stay safe while you sand

Sanding is noisy and dusty. The sanders on our comparison page list sound levels from 84 to 92 dB, so hearing protection is a sensible choice for every session.

Wear safety glasses and a dust mask or respirator rated for fine dust. If your deck is old and may have been painted decades ago, check whether the paint could contain lead before you sand it, and follow local guidance if it does.

• Use hearing protection, safety glasses and a dust mask or respirator.
• Plug corded sanders into a grounded outlet, and keep the cord behind you and away from the belt.
• Use an outdoor-rated extension cord that matches the tool's power needs, and keep connections off wet ground.
• Do not sand in rain or on damp boards when using a corded tool.
• Charge several batteries ahead of time if you use a cordless model, so you do not rush the last boards.
• Keep children and pets off the deck until you have cleaned up the dust.

Clean up and finish the deck

When sanding is done, sweep the deck and vacuum or blow off the dust. Wipe the boards with a damp cloth or rinse lightly, then let the wood dry again before you apply stain or sealer. Dust left on the surface can cloud the finish.

Run your hand over the boards, with the grain, to find splinters or rough spots. Sand those spots again with fine grit.

Apply your stain or sealer soon after the wood dries. Bare wood weathers quickly, and a fresh coat protects the work you just did.

Frequently asked questions

Can I sand a deck with only an orbital sander?

Yes, on a small deck or one with a thin finish. It will take much longer than a belt sander on thick old stain or heavily weathered boards.

Should I sand a new deck?

Often a light sanding helps smooth rough spots and open the grain so stain soaks in evenly. Let new wood dry out as the stain maker recommends first.

How do I avoid swirl marks or gouges?

Keep the sander moving, work with the grain, and do not press down hard. Change to a fresh belt or disc as soon as the abrasive stops cutting.

Do I need to sand between boards?

You can reach the edges and gaps with a narrow detail belt or a hand sanding block. A scraper can also help remove stain that has collected in the gaps.