How to Stain and Seal a Wood Pergola

If you are building a wood pergola, you might want to consider staining and sealing the lumber before the pergola is constructed. This article shows products that work beautifully on a modern two-town pergola, as well as how to apply them effectively.

It should be noted here that staining and sealing a wood pergola, deck, or other outdoor structure doesn’t require two separate coats of stain and then sealant. In fact, the opposite is true. Stain isn’t like paint, in that it’s better to do two or three coats for optimum coverage. Stain penetrates into the wood and actually changes the wood itself. It must be absorbed into the wood. Anything you put on top of the stain – even another coat of stain – won’t be able to absorb into the wood like the first coat, so you’ll just end up with a slimy or tacky surface forevermore.

One thorough but sparing coat of stain + sealer is the perfect protective covering for wood surfaces. Clear sealant provides the water- and weather-proofing element that stain does, but without the UV protection. So the color of your clear-sealed wood will eventually change to a greyed-out version.

If you know what stain you want to use before the pergola is constructed, it is much easier to stain your lumber now. In this case, lay all of your boards to be stained on some scrap 2x4s or something else elevated. Be sure the ground can handle some drips; grass, dirt, or even concrete underneath will likely get a little stain on them.

Use a medium sandpaper (180-grit was used in this example) to lightly sand all sides of your pergola boards. This takes some time, but it’s important to open up the wood pores to let the stain penetrate deeply.

The rafters on this wood pergola will be a natural stain (Sikkens ProLuxe, available at our local paint store), and the frame of the pergola will be matte semi-transparent black.

Use a 4” brush and, keeping a wet edge, brush your stain evenly onto the lumber. Apply in a single thin but thorough coat along the grain, taking care to avoid brush marks. These will be visible after the stain has absorbed into the wood and dried, so the more you can do to apply an even coat of stain, the better your end result will be.

Allow the stain to dry thoroughly, probably 24-72 hours depending on your climate, temperature, and humidity.

You’ll also want to brush away drips down the side of your boards before they dry. (The actual application of stain is detailed more thoroughly later in this article with the pergola frame’s staining.) Rotate the lumber and apply stain in the same way on all four sides, allowing thorough drying between applications. When the stain has thoroughly dried on all sides of your lumber, you’re ready to install the rafters onto your wood pergola.

While there are many brands and types of wood stain, Cabot is an excellent choice available at most hardware stores. You’ll need to choose between semi-solid and solid stain. Essentially, solid stain gives an opaque look that resembles paint. Semi-solid, which is what this example uses, provides a staining color but allows the wood grain to show through. It’s less saturated than solid stain.

Use a natural brush that is proportionate to the lumber you’re staining. After stirring the stain very well, dip the bottom half of your bristles into the stain.

Apply it onto your lumber in long, even strokes. You’ll want to apply the stain in small sections at a time. Don’t overbrush. The more you brush the stain, the more likely you are going to see brush strokes after it dries, even with the semi-solid stain.

If your lumber is normal, it will likely have an imperfection or two. To minimize the appearance of these imperfections after the stain has dried, load up some stain onto your brush and dab the bristle tips into the imperfection.

After the lumber imperfection has been saturated, continue your long brush strokes down the board.

Before the stain starts to dry, stain the sides of the board to brush away any drips. This is important to do now while the stain is fresh, because if the drips are allowed to dry, they will be obvious (darker) and look odd on your pergola.

Repeat this staining process on the top and sides of all of your boards. Double check for brush strokes and/or drips or anything that doesn’t look seamless in your stain finish.

You don’t need to worry about the ends of your lumber at this point, unless you have cut your wood to size. The benefit of cutting your wood to size before installing the pergola wood is that you don’t waste any stain. The disadvantage is that you don’t have even 1/2″ of wiggle room in construction, should you need it. This example will trim the boards during construction.

Allow the stain to dry completely, at least 24 hours. Don’t let it get wet or dirty during that time, as this will significantly affect the stain finish.

When the stain has dried thoroughly, flip the boards over and repeat the process on the undersides of your lumber. Remember to stain in long, even strokes, and check for drips down the sides again.

With the stain fully absorbed and dry, you are ready to build your pergola. Of course, you can always apply stain after the pergola is built following these steps. Just keep in mind that any transition from one stain to the next (for a two-tone pergola like this one) isn’t like paint, where one coat of stain can be applied loosely or sloppily with the expectation that the alternate coat of stain will cover it up. Stain doesn’t work like paint.

Although you might be anxious to get moving on the construction of your redwood pergola, if you have the option, it’s highly recommended that you stain first. When it’s all built, you’ll be glad you did. We hope you find this article on how to stain and seal a wood pergola helpful, and that you are able to create a beautiful yard feature that will improve your outdoor quality of life for years to come.