Sand Rough Spots
Smooth splinters and rough edges on railings and decking before finishing. Use 80-grit sandpaper on problem areas and round over sharp corners for a safe, comfortable surface.
Quick Summary
1-3 hours
$10-$30
Easy
80-120
Why Sanding Matters
Your deck might look finished after the last board is installed, but there's one more essential step before you can safely walk barefoot or let kids play on it. New lumber, especially pressure-treated wood, often has splinters, rough spots, and sharp edges that can cause painful injuries.
The Barefoot Test
Walk your entire deck in bare feet or thin socks before your final inspection. You'll quickly find every rough spot, splinter, and sharp edge that needs attention. Mark problem areas with painter's tape as you find them.
Tools and Materials Needed
Essential Tools
- 80-grit sandpaper (for rough spots)
- 120-grit sandpaper (for finishing)
- Sanding block or orbital sander
- Painter's tape or chalk (for marking)
Safety Equipment
- Safety glasses (sawdust protection)
- Dust mask (especially for treated wood)
- Work gloves (to avoid splinters)
- Knee pads (comfort for deck work)
Step-by-Step Sanding Guide
Inspect and Mark Problem Areas
Walk the entire deck, running your hands along railings and carefully feeling the deck surface. Mark every splinter, rough spot, raised grain, and sharp edge with painter's tape so you can find them all during sanding.
Sand Deck Boards
Using 80-grit sandpaper, sand each marked area on the deck surface. Always sand WITH the wood grain, never across it. Apply moderate pressure and make long, even strokes. For large areas, an orbital sander saves significant time.
- - Focus on board ends where splinters are most common
- - Sand any raised grain that could catch bare feet
- - Don't over-sand - wood needs some texture for stain absorption
Smooth Railings and High-Touch Areas
Railings deserve extra attention since hands constantly touch them. Start with 80-grit to remove roughness, then follow with 120-grit for a smooth, splinter-free finish that's comfortable to grip.
- - Sand the top rail thoroughly - most hand contact
- - Don't forget baluster tops and sides
- - Check post tops for sharp edges
Round Over Sharp Corners
Factory-cut lumber has sharp 90-degree corners that are uncomfortable and can cause splinters. Use sandpaper to create a slight round or chamfer on all exposed edges, especially on railings, stair treads, and post tops.
Clean Up and Final Check
Sweep or blow off all sanding dust. This is especially important if you'll be staining soon - dust prevents proper stain adhesion. Do one final barefoot walk-through to ensure you haven't missed any spots.
Common Problem Areas
Board Ends
Cut ends of boards often have the worst splinters. Sand these thoroughly and round over all cut edges.
Stair Nosings
The front edge of each stair tread takes abuse. Round over for comfort and to prevent chipping.
Post Tops
Even if you're adding post caps, sand the tops smooth. Sharp corners can cut hands during installation.
Knots and Defects
Wood knots can be rough and raised. Sand carefully around knots to smooth without creating a depression.
Power Sander vs. Hand Sanding
When to Use a Power Sander
An orbital sander or palm sander is ideal for deck boards and flat surfaces. It saves hours of work on larger decks. Use 80-grit discs and keep the sander moving to avoid creating gouges. Random orbital sanders leave the smoothest finish.
When to Hand Sand
Hand sanding gives you more control for railings, balusters, and detail work. Use a sanding block for flat surfaces and folded sandpaper for contours. Hand sanding is also better for spot work around fasteners and edges.
Pressure-Treated Wood Tips
Safety Warning
Pressure-treated lumber contains chemicals that can be harmful if inhaled. Always wear a dust mask rated for fine particles (N95 or better) when sanding treated wood. Work outdoors with good ventilation and wash hands thoroughly afterward.
- - Never burn pressure-treated sawdust or scraps
- - Dispose of sawdust in regular trash, not compost
- - Shower after extensive sanding work
Frequently Asked Questions
What grit sandpaper should I use on deck boards?
Start with 80-grit sandpaper for rough spots and splinters, then follow up with 120-grit for a smoother finish on high-touch areas like railings. Avoid going finer than 120-grit as the wood needs some texture to absorb stain and prevent slipping when wet.
Should I sand my entire deck before staining?
You don't need to sand the entire deck surface unless it's very rough. Focus on sanding splinters, raised grain, rough spots, and sharp edges. Over-sanding can actually prevent stain from penetrating properly. Light sanding of the whole surface is fine if boards are fuzzy.
Can I use a power sander on deck boards?
Yes, an orbital sander or palm sander works well for deck boards and saves time. Use 80-grit discs and keep the sander moving to avoid creating divots. For railings and detail work, hand sanding gives you more control. A belt sander is too aggressive for most deck work.
How do I remove splinters from pressure-treated wood?
Sand splinters with 80-grit sandpaper, always moving with the wood grain. For stubborn splinters, use a sharp utility knife to carefully slice them off flush with the surface, then sand smooth. Pressure-treated wood often has more splinters when new but improves as it weathers.