6 Ways to Treat Wood for Outdoor Use


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July 7, 2023
Zoe Hunt

When planning an outdoor project using wood, you’ll want to be sure to treat the wood for outdoor use. Harsh UV rays, water, and temperature fluctuations can cause wood to deteriorate much faster than it would indoors. 

Some woods like teak, cedar, and redwood are all great choices for outdoor furniture and DIYs because they contain natural oils that help protect against water damage. That said, you can extend the lifespan of any wood (yes, even pine), by treating it for outdoor use before exposing it to the elements. 

In this post we’ll cover a handful of ways you can treat wood to get it ready for outdoor use. We’ll also briefly discuss how you can make your outdoor furniture last longer. 

Wood Finishes for Outdoor Furniture + Projects

how to finish wood for outdoor use text overlay on image of 4 different outdoor sealers

There are several different ways to waterproof and treat your wood for outdoor use. Any of the options below offer great protection against water. Which one you choose will depend on the look you’re going for and how often you’re willing to maintain it. Of the options we’ll discuss, Spar Urethane and an Exterior Stain and Sealer in one will provide great protection with the least frequent maintenance. 

Spar Urethane 

Spar Urethane is one of our go-to exterior finishes due to its durability and exceptional protection from the elements. Spar Urethane was originally used on boats, so it knows a thing or two about resisting water and UV rays. 

It forms a protective layer that shields wood from moisture, preventing warping, rotting, and decay. It comes in a few different sheens ranging from satin to gloss. Whichever option you choose, you’ll add a little more shine to your projects than most of the other options we’ll discuss. 

Spar Urethane will generally last a while and requires minimal maintenance once applied. When applying, you need to apply at least 3-4 coats for proper protection and waterproofing of your wood. This can be a labor intensive process upfront. 

Minwax Spar Urethane in Clear Satin sitting in front of wooden planter
Typically we use the Helmsman Spar Urethane instead of this can, but both work great!

If you choose an oil-based Spar Urethane, it will amber overtime and add a slight yellow hue to your wood. The water-based Spar Urethane will minimally change the color, but it generally isn’t quite as durable as an oil-based option. That said, we still generally use the water-based option.

You can choose to apply Spar Urethane straight onto the natural wood or you can apply it over any stain (it doesn’t need to be an exterior stain). 

Exterior Stain + Sealer

If you’re looking to add some color to your wood, an Exterior Stain and Sealer In-One can be an awesome option. A big benefit of this type of finish is that it generally only requires one coat to apply and protects against both water and UV rays. 

There are a lot of different colors and transparencies offered, so you can really change up the look of your wood.

We’ve used everything from blue colored stains on our DIY giant Connect 4 and DIY hammock stand to a more natural brown shades on our DIY privacy screen and tall slatted planters

Cabot Siding and Fence Solid Color Stain and Sealer being used to treat wood for outdoor use

There are transparent and semi-transparent stains that really let the wood grain shine through. Or you can grab a solid stain for more even coverage. It looks almost like paint as you can see on our DIY porch swing. 

The big advantage of this exterior stain and sealer compared to paint is that it is made for wood. Rather than sitting on top of the surface, it actually penetrates into the wood to protect it while still allowing it to breathe. 

I also love that the wood grain still shines through in certain lighting when using a solid stain vs. a paint. It’s subtle, but still allows you to celebrate the wood grain. 

screened in deck stained with Cabot Solid Stain and Sealer tinted to Valspar's Fired Earth
This deck was finished with Cabot Solid Stain + Sealer tinted to Valspar’s Fired Earth.

If you don’t want to go fully solid, but still want a little more coverage than a semi-transparent stain, a semi-solid stain might be a good option for you. We used a black semi-solid stain for these giant DIY planters and matching DIY privacy planter wall

As you can see, there are a ton of finishing options with exterior stains and sealers, but it can still be a bit tough to find the right color. Most color samples are tested on cedar, so if you’re using pine or another wood, the color will likely look pretty different, especially if you’re using a light transparency. 

We’ve also noticed that the more natural stain colors tend to look a lot more orange in person than they do on the sample wall. Keep that in mind when selecting your color!

Another thing to note about exterior stain and sealers is that they are a little more difficult to apply than a traditional oil-based wood stain. They tend to dry really quickly, so you need to be very aware of drips and avoid going over the same area twice to avoid lap marks. They also dry with a flat finish, so you won’t have any shine with these options. 

We’ve tried a handful of brands and like Cabot stains the best. 

Tung or Linseed Oil

Tung oil penetrates deeply into wood, nourishing and strengthening it from within. This natural oil forms a protective layer on the wood surface, shielding it from moisture, UV rays, and other environmental factors.

Linseed oil is derived from the seeds of the flax plant and has been long used as a go-to option for finishing wood furniture. It’s very water-repellent, making it a great choice for outdoor use. Because linseed oil penetrates the wood fibers, it prevents moisture from seeping into the wood and causing swelling, warping and rot. If going with a linseed oil finish, be sure to grab boiled linseed oil. 

Though these oils will not add pigmented color to your projects, they will brighten up and enhance the natural color of the wood, making it appear much brighter and more saturated than it was before the oil was applied. 

These oils generally take a few days (maybe even up to a week) to dry, so you’ll need to plan accordingly if you want to choose one of them. They will also require re-application every six months to a year, but are non-toxic, making them a good choice for things like raised garden beds.

Thompson’s WaterSeal

Thompson’s WaterSeal is another good option for waterproofing outdoor furniture. It forms a protective barrier that prevents moisture penetration, which can reduce the risk of warping, cracking, and rotting. Instead of soaking into the wood, water will just bead right up when it comes into contact with something treated with Thompson’s WaterSeal. 

It’s easy to apply and dries fairly quickly, but you will likely need to reapply it ever year.. Like the oils mentioned above, it’s transparent and will not add color pigments to your wood, but it will enhance the natural color. 

One thing to note about Thompson’s WaterSeal is that its primary focus is repelling water. It offers limited protection against UV rays, so over time your wood color will very likely fade. 

In fact, we sealed our DIY modern adirondack chair with Thompson’s WaterSeal a few months ago and the seat and back (which get the most direct sunlight) has already lost most of its natural orange cedar color. 

DIY modern Adirondack chair finished with Thompson's Waterseal

Exterior Paint

If you’re looking for an option that hides the wood grain as much as possible and provides an extremely wide range of colors and sheens, exterior paint might be the choice for you.

With proper surface preparation and application, high-quality exterior paints create a durable and resilient barrier on the wood surface. This barrier shields the furniture from moisture, UV rays, and temperature fluctuations, helping to prevent warping, rotting, and fading. 

Additionally, exterior paint offers a smooth, uniform surface that can be easily cleaned and maintained over time. Our DIY outdoor bar cart still looks brand new over 3 years later. 

Unlike stains and oils, the exterior paint does not soak into the surface of the wood, so it is more prone to peeling over time. 

Our go-to exterior paint line was recently discontinued, so I’ll keep you posted on if we find a new favorite. Sherwin Williams recently released a new self-cleaning “Rain Refresh” line that supposedly will clean right off with rain or water – minimal maintenance sounds promising to me!

Spray Paint

I know this one seems a little out of the ordinary, but you can finish wood furniture with spray paint. If you have something small like this DIY side table, spray paint can be a quick and cost-effective option. 

The key here is to grab a spray paint that is specifically formulated to last outdoors. We love using Krylon Fusion All-In-One because of its durability and versatility. You can use it on pretty much any surface (wood included) and it’s long lasting. 

We spray painted this outdoor side table over 3 years ago and it’s still looking good as new, even though it’s been sitting outside in mulch and has never been covered to protect it from the rain.  

How to Apply an Exterior Finish on Wood 

Whatever option you choose, you’ll want to follow the instructions on the back of the can when applying.

Whether the stain or sealer is oil-based or water-based will impact what type of brush or applicator should be used. Some stains require wiping off the excess while others explicitly say not to wipe after applying. Though the print is small, the exact instructions for application will be laid out on the can. Follow the instructions for your particular finish. 

I’d also recommend testing out the finish before applying to the whole piece. This will allow you to see the color and get some practice with applying the finish.

How to Make Your Outdoor Furniture Last Longer 

Now that we’ve discussed different options for finishing your outdoor wood furniture to protect it from the elements, let’s talk briefly about further protecting your wood furniture so it lasts longer.

Maintaining Your Wood Finish

First, you’ll want to stay on top of maintaining the finish you added. As much as it would be nice to finish your wood furniture once and never think of it again, all wood that’s outdoors will need some maintenance over the years. 

How frequently you need to reapply your finish will depend on what finish you used and the weather conditions in your area. The more sun and water a piece of wood comes in contact with, the more frequently it will need to be refinished or maintained. 

Some finishes recommend reapplying every single year, while others claim to last up to 8 to 10 or even up to 25 years. In general, a more solid opacity finish should last longer than a more transparent finish.

Look at your particular finish to see if there is a recommendation on how long it should last. Some finishes, like Thompson’s WaterSeal, will tell you to splash water on the surface. If it beads up, you’re still good to go. If the water begins to soak into the wood, it’s time to reseal. 

water beading up on wooden outdoor chair that was treated for outdoor use

Regardless of how long the exterior finish claims it will last, it’s important to continue looking for signs of wear and tear. If you start to notice that your finish is beginning to look a little rough, recoat and reseal your wood furniture. 

Staying on top of maintaining the finish will help your wood furniture last longer outdoors. 

Protecting Your Wood Furniture 

Another way to protect your outdoor furniture is to use a waterproof cover. This is especially useful to furniture that cannot be easily moved and is not in a covered area like a screened porch or covered patio. 

Waterproof covers can be made from a variety of materials, including canvas, polyester, and vinyl. Be sure to choose a cover that fits snugly and is designed for outdoor use. Placing a cover over your outdoor furniture when not in use will help protect it from the elements and will help your finish last even longer. 

If you have a garage or shed, you can also store it during the offseason. Moving furniture to a covered location or indoors can significantly extend its lifespan. 

Summary of How to Treat Wood for Outdoor Use

In conclusion, waterproofing your outdoor furniture is essential to keeping it looking great and protecting it from the elements. The first step is choosing an exterior-grade finish for your wood furniture. Spar Urethane, Exterior Stain + Sealer All-In-Ones, Linseed or Tung Oil, and Exterior Paint are all great options to help protect your wood furniture from the elements.

After finishing your wood furniture to give it a waterproof finish, be sure to maintain the finish. You can also grab a waterproof cover or store your furniture indoors during the offseason to help protect your wood outdoor furniture to help it last for years to come.

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how to waterproof wood text overlay on image of water beading up on wooden outdoor furniture
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