Sanding a deck seems simple. Fire up the sander and make a few passes. Pump the brakes a bit. There’s more to it. I wanted to share some quick tips with Long Island homeowners on how to sand a deck the right way.
Your spring to-do list might include sanding your deck in preparation for paint or stain. Or, your goals may lie in exposing new wood fiber. Either way, I want to walk you through the preparations you should take before sanding and how to sand like a pro once it’s go time.
How to sand a deck the right way — Prep
Look. Do yourself a favor and fix any outstanding issues before sanding your deck. I’m talking about replacing warped boards and setting fasteners below the decking surface. These steps will save you tons of time and increase your safety (more on these in a bit).
Wear safety glasses and ear protection as well. I’d also add in a face mask and some knee pads. Sanding kicks up tons of dust and takes a toll on the body. So, now that you’ve got yourself ready, here are the steps needed to sand a deck the right way.
Step 1: Selecting the right tools
Easy enough: you need the right tools for the job. Not every sander will do the job well. Belt sanders may damage your wood (especially if you’re new to all of this). Stores like Lowes and The Home Depot have floor sanders you can rent to do the job well and save time.
I’d go for an oscillating spindle sander or a random orbital sander.
These sanders excel at removing old stains and blemishes from large deck boards while avoiding unsightly scratches. Use a detail sander for tight spaces where you need a little finesse. These compact tools make sanding around posts and balusters much easier.
Now, let’s talk sandpaper.
Choosing the appropriate grit for sandpaper is essential for your project because the initial surface determines what grit to use. Your primary choice for sanding deck boards and stairs should be 60- or 80-grit sandpaper. For railings and posts you should use 80- or 100-grit sandpaper because you need a smooth finish on surfaces people will touch.
Dealing with some seriously weathered spots? Begin with 40-grit sandpaper but move to a finer grit as you make your passes.
Keep this in mind: sanding above 100-grit could prevent stains and sealants from working effectively. I wouldn’t go above 80. Here is a list of some other tools you might need to complete the project:
- Blower
- Compressor
- Hammer
- Impact Driver
- Stiff bristled brush
- Kakuri nail punch
- Sanding Discs
- 3-in-1 cleaner/fungicide/brightener
If you take the time to prepare the surface, you’ll achieve a professional-grade finish.
Step 2: Clean the Deck
To get ready for sanding, you’ve got to get your deck clean. All that dirt, grime, and mildew have to go.
Skipping this step is a bad idea. Your sand paper will be less effective. Cleaning your deck’s surface allows for better application results and helps the stain or paint you’re applying set better. Begin by taking all furniture items, potted plants, grills, and decorative pieces off your deck.
Once the surface is clear, you’ll need a deck cleaner made from biodegradable materials to remove dirt and mildew. If you prefer a DIY approach, mix two gallons of warm water and two cups of powdered oxygen bleach because it does not harm plants (that’s not the case for chlorine bleach). Mix in a fourth of dish soap.
Use a soft-bristle deck brush or broom to scrub the solution gently against the surface to remove grime. Rinse thoroughly with a garden hose.
Power washers accelerate cleaning tasks but require proper use to protect wooden surfaces from harm. Maintain pressure settings between 500 and 1,200 PSI while keeping the spray nozzle 12 to 18 inches from the surface. Select a fan-tip nozzle when washing wood to ensure water spreads evenly across the surface while preventing any wood damage.
You can also help return your deck’s natural color by applying a wood brightener when it becomes gray. Older decks that have lost their shine after ten years of UV exposure and moisture exposure benefit greatly from this step.
The deck needs to be completely dry for 24 to 48 hours after cleaning before beginning sanding. Sandpaper will become clogged when sanding damp wood, resulting in an uneven surface finish.
A deck that has been cleaned properly and allowed to dry will enable more efficient sanding to achieve a smooth and professional-looking finish.
Step 3: Fix the fasteners
If you own a deck that is over 20 years old, you likely have 16-penny nails keeping everything in place. But here’s the problem: wood expands and contracts. This natural process causes the nails to slowly rise to the deck surface over time. You’ve got work to do.
Sink the fasteners at least ⅛ inch beneath the deck surface. Working on a hand-nailed deck means you’ll need to befriend both a nail set and hammer.
Pro tip: The Shark Corp Nail Punch and Kakuri Nail Set are essential tools that make working with nails much easier by increasing your target area.
While newer decks appear easier to work with because they use cordless drill-installed screws this is misleading. The little metal devils carry their own unique set of challenges. A screw that looks good from above may actually be entirely damaged underneath.
When you run into seriously deteriorated fasteners, you’ve got two paths: replace the problem board or do a complete deck resurfacing.
Considering these steps might seem over the top, but believe me when I say that tackling the problem now prevents bigger issues later.
Step 4: Sand, sand, sand
Once your deck has been cleaned and dried, you can move on to the actual sanding. Finally! It’s time erase years of weathering and wear.
Sanding isn’t complicated but you have to know the method to do it right.
When operating a large round floor sander, use smooth overlapping passes similar to painting or lawn mowing. Now, the real magic lies in the sandpaper.
60-grit sandpaper removes coarse surface material. You can then switch to a softer 80-grit paper that works like a loofah to achieve a smooth finish. You should use 80-100 grit sandpaper for precision work on railings and posts.
Pro tip: switch your sandpaper for a new one when it acts more like a back scratcher than a tool for sanding.
In between sanding sessions use a leaf blower to remove dust particles or a vacuum cleaner for an upscale cleaning experience.
After you finish sanding you’ll have a rejuvenated deck surface.
Quick Summary
Sanding a deck might look easy but proper execution demands both thorough preparation and appropriate tools. Following the correct procedures when repainting or restaining wood will lead to a professional-quality finish.
Preparation is key. Inspect your deck for warped boards and protruding fasteners before beginning the sanding process. Make sure nails are driven at least ⅛ inch below the wood surface to avoid damaging sandpaper.
The dust produced during sanding makes it essential to wear safety glasses and a face mask while knee pads will protect your knees.
Deck cleaning prevents sandpaper blockages and maintains surface uniformity.
Choose between a biodegradable deck cleaner or make your own oxygen bleach solution to eliminate grime. Maintain power washer pressure at 500–1,200 PSI when cleaning to protect the wooden surface from harm.
Ensure the deck stays dry for 24 to 48 hours before you start sanding.
A random orbital sander is essential to achieve uniform coverage during the sanding process. Select 60-grit sandpaper for removing large amounts of material and use 80-grit sandpaper to smooth surfaces. To achieve optimal results sand by overlapping passes while checking for worn sandpaper and removing dust between rounds.
Now you have the 4 steps you need to breathe new life into your deck. Time to sand!
