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What Grit Sandpaper For Deck? [And Railings]

Sanding is an important finishing step to ensure a smooth surface for your deck. Sandpaper is available in a wide variety of grits to do the job. But what grit sandpaper should you use for the deck? And which should you use for railings? We researched these questions and have answers to share.

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Use 60- or 80- grit sandpaper with an orbital sander or belt sander on your deck. Use 80- or 100- grit sandpaper with a hand-held sander on handrails or railings. 

The higher the grit number, the finer the sandpaper. Fine sandpaper is best suited for refining surfaces. The lower the grit number, the coarser the sandpaper. Coarse sandpaper is best for tough sanding jobs.

You may be ready to order the specific grit sandpaper by the numbers, but sanding requires more details than the grit numbers on your sandpaper. Read more about sandpaper application and tips for a sleek sanding project for your deck and railing.

Using a power tool to sand a wooden deck, What Grit Sandpaper For Deck? [And Railings]

Sanding Your Deck And Railings

You may have just installed a deck and railing or you're planning to paint, oil, or stain your old deck. Sanding is just one of the many jobs on your task checklist for your deck project.

Skipping or ruining one step of your project may ruin the whole project. This sandpaper grit guide is for you.

Carpentry sanding the wooden deck using a power tool

Choosing Sandpaper 

Grit numbers can run from 20- grit to 400- grit or more. There are two organizations that determine the grit of sandpapers: the Coated Abrasive Manufacturers Institute (CAMI) and the Federation of European Producers of Abrasives (FEPA).

Big rolls of sandpaper

Some sandpaper bought online is ranked according to FEPA standards and will have a P before the grit number. An example would be P-40. Meanwhile, sandpaper using the CAMI scale has tags such as 40-grit or 80-grit.

For The Deck

Get 60- or 80-grit sandpaper for your deck. As mentioned earlier, the higher the number, the finer sandpaper is.

A 40- to 60-grit would be considered a coarse type of sandpaper best for heavy sanding, since the main deck is exposed outdoors. An 80-grit sandpaper is medium and commonly chosen for wood prefinishing.

For The Railings

You should use 80- or 100-grit sandpaper for railings. Sandpaper with 100- and 120-grit have fine grains. They can polish scratches, chip out the paint, and file drywall.

Check out these 100-grit sandpaper sheets on Amazon.

Choosing Sanders 

Use a suitable sander for your deck and railings to make your work light and easy.

There are specialized sanders on the market geared toward different surfaces and areas. Find out what type of sander is best for your wood deck and railings.

For Deck

Use an orbital sander or belt sander for the deck. A belt sander is ideal for preparing the wood. It can also get rid of any material from the wood quickly. Some features of a belt sander are: 

  • Powerful and fast-moving.
  • Ideal for aggressive work.
  • Suitable for large and leveled areas.

Check out this inch belt sander on Amazon.

An orbital sander allows you to move your sander in all directions, but it's weaker than a belt sander. If you have a softwood deck, you may use this type of sander so as not to damage your deck surface.

Here are some of its features:

  • Good for sanding, shaping edges, and finishing details
  • Moves flexibly and gets in every corner
  • Ideal for shaping and fining curves
  • Not suitable for large piles of wood

Check out this orbital sander on Amazon.

For Railings 

A palm sander is lighter and smaller than an orbital sander. It only performs an orbiting movement.

A palm sander is much easier to control than an orbital sander. It is the best sander for railings, since it can be used for fine-sanding jobs.

Check out this electric detail sander on Amazon.

Sanding Considerations

Power spraying a wooden deck

Aside from knowing what tools to use, there are other things to consider before applying your sander to your deck and railings.

Keep the factors below in mind, as they can save you from ruining your project, especially when you decide to DIY.

  • If you have a new deck, wait a month or more to season and dry the wood. Check by sprinkling some water on the wood. If it absorbs the water, you can start sanding.
  • Clean the deck by sweeping or vacuuming. Wash it with water and then thoroughly dry the wood for at least a day before starting to sand it.
  • You should know what wood your deck made of in order to match it with the correct sander. Cedar, pine, redwood, and most pressure-treated woods are softwood.
  • Check the weather. You need at least three consecutive sunny days for your deck to dry off after it rains.
  • Inspect for cracks, dents, and any nails protruding from the wood. This is an important safety precaution.

Steps For Sanding Your Deck

Carpentry equipment's on a table

In sanding a deck, be ready with your tools and have it scheduled for a few days straight. There are not a lot of steps in the process, but starting and ending it right makes the sanding look smooth and well-maintained.

  1. Wear gloves, glasses, and a mask, because dust will be everywhere in the area once you start sanding.  
  2. You can begin with coarse-grit sandpaper and then move on medium- and fine-grit sandpaper to have a smooth finish.
  3. Move your sander through the boards backward and forward. Do the same during the second sanding.
  4. Use a flexible sander to reach the edges and sharp corners of the deck.

Steps For Sanding Your Railings 

Carpenter using power sander on his project

With railings, carefully sand every side. Check each post for any signs of rot or damage. Outdoor railings exposed to harsh weather require regular maintenance.

  1. Check for any raised nails to avoid accidents.
  2. Sand the whole handrail from top to bottom.
  3. Use coarse-grit sandpaper on bumpy surfaces.
  4. Fill in any dents or hollows. You can use the sanding dust to make a wood fill.

Can I Use 120 Grit Sandpaper To Sand My Deck?

You can start with 60-grit as your first sanding. Go higher with your second sanding to 80- grit sandpaper. Finally, you can use 100 to 120-grit sandpaper for a smooth finish.

Is It Better To Sand Or Pressure Wash A Deck?

Do both when you're going to seal your deck. First, pressure-wash your deck to remove the dirt and any blemishes caused by outside exposure. Let it dry for 24 to 48 hours. Then sand it to smooth out any imperfections.

Does Sanding Ruin Pressure-Treated Wood?

It's a warning sign if sanding pressure-treated wood partially removes the coating made by the treatment. If this happens, you'll end up with a bad deck.

Can A Wet Deck Be Sanded?

You should never sand a wet deck, as it will cause the wood to warp, shred, or crack. While the moist sawdust will not be blown away, it can get damp and stick to the deck.

Pressure-wash the deck and let it dry completely before resuming or starting sanding.

How Much Does It Cost To Sand A Deck?

The average cost to sand a deck is $280. It usually takes seven hours to sand a 200-square-foot deck. Professional labor for this can be around $350. If you're considering DIY, add up all the necessary tools you need, starting with a sander.

Summing Up

Using a power tool to sand a wooden deck

Sandpaper has different grades for various types of wood.

Knowing which grit grade to use for your deck and railings can help you start your sanding project properly. Use 60- or 80-grit sandpaper for the deck, and 80- or 100- grit for the railings. 

Read these posts about grit sandpaper and more: 

What Grit Sandpaper For Wood? [Raw And Painted]

What Grit Sandpaper For Drywall?