Deck StainingSanding

Common Issues when Sanding a Deck and How to Solve Them

You can expect your wood deck to fade and turn gray over time. Not even the best exterior wood deck stains can protect your wood forever, so eventually, you’ll need to consider sanding your deck and reapplying a brand-new wood stain that’s perfect for your deck wood.

While the basic principle of sanding a deck can seem simple, you may find that you need more than just some elbow grease and a belt sander to get the job done. In this guide, we’ll look at the sanding process from start to finish, including some prep that can help you save a lot of time in the future.

Sanding the Wooden Deck Boards

Testing Your Current Deck Stain

While it’s tempting to simply jump in and sand your entire deck surface with an orbital sander and some sandpaper you found lying around, doing your prep properly can help reduce the incidence of common deck sanding issues.

Start by examining your deck for any protruding nails or screws or rotten wood. Fix these issues before you even consider moving onto the next step.

Staining a brand-new deck is a relatively simple process, but it becomes more complicated if you have an old deck. Some older pressure-treated lumber may contain arsenic, and sanding this wood surface would be incredibly hazardous to your health.

Manufacturers of pressure-treated pine stopped adding arsenic in 2003, so do your research before you start sanding. If you have a new deck or an older deck built from redwood or tropical hardwood such as teak, you should be fine.

Sanding Can Reduce Wood Deck Stain Penetration

Overzealous sanding can do a lot of damage to bare wood or even pre-treated redwood or cedar deck boards. If you find that the wood doesn’t accept wood stains after sanding, chances are you’ve over-sanded with sandpaper grit that is too fine, and crushed the grain of the wood pores.

A good rule of thumb is to start with a sander and finish off with coarse sandpaper, palm sander, or a coarse sanding sponge. Your sandpaper grit should be around 60 or 80 grit – anything more will crush the wood grain shut and make staining your deck floor more difficult.

The type of sander you choose will depend on your deck:

  • A belt sander is great for the first round of sanding. Belt sanders struggle with smaller spaces, but they’re excellent for a large surface area.
  • A drum sander or power sander is ideal for removing stubborn paint and stains. Drum sanders can do a lot of damage if you’re not careful, so use them with caution.
  • Orbital sanders are incredibly easy to use and a common DIY and deck project tool. They provide gentle sanding that’s great for softer wood, especially if you start with coarse grit sandpaper and work your way to a finer grit.
  • A random orbit sander has more power and is great for sanding decks with stubborn paint or stains.
  • The detail sander, or palm sander, is your go-to tool for fine details like railings, corners, and board sizes.

If your deck is old, or it’s the end of winter, and you haven’t cleaned it for a while, consider using a power washer before sanding. It will eliminate the debris on the top layer of wood and make your sanding experience much more hygienic and pleasant. It’s also important to rinse the wood after sanding. You can use a garden hose, or a pressure washer for this. This will remove any sawdust that is present on the surface. Sawdust that is left on the surface while staining will create an uneven, blotchy appearance.

Make sure to utilize proper safety gear, including a respirator and eye protection, to protect your health through the process. Don’t make the mistake of neglecting your protective gear: sanding results in wood dust, which can cause damage to your lungs if inhaled.

Sanding Railings and Board Sides

Sanding a deck board is a relatively simple process, but sanding railings and board sides can be tricky. We recommend either using a detail sander or hand-held sandpaper to do the job. Make sure to choose the right grit for your wood type – harder woods require coarser grit than soft woods.

We recommend starting with 20-grit for hardwood and 50-grit for softwood for the initial sanding. While you want a good finish for your stain, you don’t want a smooth surface that won’t take any decking stains or absorbs it very slowly.

Staining

Once you’ve got your whole deck sanded, the next step is to give it a proper clean. Pressure washing with an oxygen bleach deck cleaner is an excellent option that removes excess grime, mildew, and oils that can inhibit deck stain absorption. Any deck stained without proper cleaning will have an uneven finish due to these minuscule imperfections.

An issue that some people have is that their power-washed wood looks darker than it did previously. That’s because deck cleaners contain alkaline soaps that raise the wood’s pH. A wood brightener contains acid that reverses this effect and ensures the wood stays at a neutral pH.

Once you’ve completed the cleaning process, let your deck dry before applying your stain. Staining directly after power washing will trap unwanted moisture in the wood, which may cause issues in the future, especially if you’re using an oil based stain. Using a water-based acrylic stain such as DEFY Extreme Wood Stain will allow you to stain a few hours after cleaning, just make sure the wood is visibly dry. Otherwise, for most other stains you’ll need to allow the wood to dry at least 24 hours.

The final step is applying your chosen stain. Choosing a stain can be challenging, but we recommend using a semi-transparent stain for a new cedar deck, pressure treated deck, or decks made from hardwoods. It will preserve the natural weathering and character of the wood while offering excellent protection. You can choose a dark stain, like dark walnut, to bring out your wood’s natural grain and texture.

Whether you’ve chosen a solid stain, semi-transparent stain, or even the same oil that was previously on your deck, the process is the same. Use a proper stain brush to avoid leaving behind brush marks, and consider using a sprayer if you have a very large deck.

Depending on your stain, you may have to wait a day or so before using your deck – more if you’ve had bad weather. Oil-based stains tend to take two days to dry, while acrylics will dry more rapidly. Be sure to read the instructions on the label for an estimate of drying times.

FAQs

Should I sand my deck?

In some cases, yes. Direct sunlight and UV rays damage lignin, the glue that holds wood fibers together. As your deck ages, it will become more porous and less water-resistant, which can lead to a host of water damage and mildew issues.

If your deck has multiple coats of stain applications, it’s a prime candidate for sanding and a new coat of sealant, stain, or deck paint.

In general, you should sand your deck every 5-10 years, though if you often experience extreme weather, you may need to do it more frequently.

Should you sand a pressure-treated deck?

It depends on the age of the deck. If you’re certain that the wood is newer than 2003, then you should be safe. However, you can also request a carpenter or decking professional to investigate for the presence of arsenic before you continue.

What happens if it rains after sanding my deck?

The weather is often your worst enemy when it comes to refreshing your deck. If you want to preserve your hard work, put a tarp over your deck after sanding to protect it while it dries.

While some wood stains can let moisture out, it’s often a better idea to wait until your wood is fully dry before applying the stain. It will produce a better finish without the concern of mildew growth under the stain.

Can you sand grooved decking?

Yes, but your results will vary depending on how much work you put in. Conventional sanding machines will sand most of the wood without any issue, but you’ll have to deal with the inside of the grooves manually.

A deck can add a lot of enjoyment to your life, but it also requires care and attention. Wooden decks are susceptible to adverse weather, and refinishing is a significant part of deck maintenance.

2 Comments
  1. […] beneficial as it neutralizes any cleaners and brightens the wood back to a new look. Alternatively, sanding the wood can also help. If sanding is necessary, be sure to use a coarse grit sandpaper and lightly […]

  2. […] Sanding can often times due more harm than good, as it can close off, or crush, the wood fiber in the boards, thus reducing the board’s ability to absorb the stain.  Sometimes though, it’s the only thing that will work.  In areas of the deck under mats, under grills, shaded by soffits etc., you may simply have no choice but to sand and, if you do, try to use a course grit paper (80D).  Using a fine grit paper will no doubt make the boards look great…you can get them as smooth as a piece of furniture…but that’s not what you want outside for staining.  Remember, every step of the process has something to do with creating porosity in the wood so that it will absorb more stain.  The more stain it absorbs, the longer the project will last.  Sanding does not help with this. […]

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