How Long Should You Wait to Seal a Deck After Power Washing? 

 February 17, 2022

By  Dale Keese

Power washing is an important step in preparing your deck before you seal it. It naturally exfoliates the wood and ensures that the sealer penetrates deeper. However, many people aren’t sure how long after power washing the sealer can be applied.

Decks should be completely dry before sealing, and waiting 24 to 36 hours is adequate before applying sealer if you have a sun-facing deck. If the conditions are humid or cold, wait 48 to 72 hours. A visual inspection can let you know if it’s dry, and when in doubt, give it another 24 hours.

When wood is thoroughly dry, there wouldn’t be any puffiness, swelling, or softness – then you can apply sealer.

There are other considerations to think of when deciding how long you can seal after power washing a deck. Read on below to learn more.

How Long to Wait to Seal Deck After Pressure Washing

Pressure washing a deck is not required before sealing it especially if it’s still in good condition.

However, it is an extremely effective method for keeping your deck clean and looking good while removing mold, dirt, and dust. It ensures that all these contaminants have been removed before sealing, and doing so will ensure that the sealer will penetrate deeper and thus be more effective at its job. For these reasons, power washing is recommended.

When deciding how long to wait in between pressure washing and sealing, weather plays the most important role.

Optimal Conditions for Deck Sealing After Power Washing

Plan to apply deck sealer on a day that’s not too windy, with temperatures ranging between 50 to 90 degrees Fahrenheit, 24 to 36 hours after power washing. Working in the morning is recommended because the heat of the sun especially during the summer can result in quick evaporation of the sealant. This will minimize proper absorption and can cause rotting.

If you want to be very sure the wood is dry enough, you can also wait 72 hours before sealing.

Keep in mind that you should never apply sealant when the deck surface is frosty or damp. It would also be wise to forego sealing during the fall or winter in these cases, if it’s extreme where you live. Doing so will lead to uneven applications that won’t protect the deck and in the worst case scenario, may even cause the sealant to bead on water. When the sealant isn’t absorbed properly due to frigid and wet conditions, water will not be absorbed and the deck will be a dangerous hazard to walk on because of slip risk.

For these reasons, working during the middle of summer is always recommended for the best results.

Other considerations for weather:

  • If rain is expected anytime within the next 24 hours, do not apply sealer.
  • If you intend to apply two coats of sealer, always wait 24 hours between the first and second coat while keeping the deck surface dry at all times.
  • Covering the deck underneath a tarp will prevent unexpected rains from seeping through.

How to Check If Your Deck Is Dry

There are a few ways you can check if your wooden deck is dry enough for sealing. Here’s how:

  1. 1
    Inspect the wood for any puffiness, swelling, or softness on its surface. Should there be none, and the wood is firm and dry to the touch, then it’s dry enough.
  2. 2
    Use a wood moisture meter. They come in pinless or pin-type varieties, though pinless meters provide better accuracy with faster results. Both work by measuring how much moisture is contained within the wood. Be sure to measure in several areas around the deck. If the moisture content is 19% or below, then it’s dry enough for sealing.
  3. 3
    Put a few drops of water on the deck surface. If it beads up, it’s still wet so it would be best to wait a few days. On the other hand, if the wood absorbs the water quickly, then the deck is dry and it’s ready to be sealed.

Power Washing Techniques

Knowing how to pressure wash your deck correctly will save you from irreparable damage that can be costly to fix.

It’s important to have the right knowledge on technique as well as having the right equipment. In addition, it’s also critical to have the appropriate power washer while operating it at the right pressure. Keep in mind that pressure washers are very powerful tools, and in some cases they can even deform a brick, which is why it’s so important to keep it at a gentle setting.

For cleaning a wooden deck, use the lowest pressure setting depending on the type of wood. Hard woods can take a force of 1200 to 1500 psi while softer wood like pine or cedar should be washed at a range of 500 to 600 psi.

On top of that, the right tips is also necessary. Ideally, a rotating tip or a fan tip is best for cleaning wood. Always start the process by pointing the tip in an area that is away from glass windows, people, and other breakable items. Stand 2 feet away from the deck then gradually go nearer but no more than 12 inches away from the deck.

Always start in an area that is easy to replace or fix, such as the stair, which is considerably simpler to repair compared to the entire deck. From here, figure out the appropriate setting then work outward while steadily holding your arm as you sweep through the deck, following the direction of the wood grain. If the wood fibers from the deck raise due to washing, sanding it is necessary before sealing.

Lastly, be sure to take precautions when power washing. Pressure washers use a high amount of force when its contents are released so it can cause injury if used incorrectly. Don’t underestimate the pressure of these tools even at a low setting.

Protect your eyes with safety glasses, and wear sturdy clothes when working; wear heavy duty rainboots to protect your feet. Wear comfortable clothing that clings to the body; if the pressure washer accidentally catches loose clothing on you, you may be pulled into the stream. And ensure that children and pets are far away from the deck.

Frequently Asked Questions

Is pressure washing enough to clean a deck?

There are certain steps to take before pressure washing a deck to ensure that the wood is properly treated:

  • If the wood is old, scrub the surface especially if there is grime. Some pressure washers are equipped with a soap dispenser so fill it up with a soap cleaner suitable for the specific wood your deck has. Cover the surface well especially those that have grime, then use a scrubbing brush to thoroughly clean through the areas you’ve sprayed on.
  • If there is any trapped debris caught between deck boards, use a putty knife to remove it. A mixture of water and oxalic acid lightly sprayed on the deck afterwards will help brighten the wood in the dark areas between deck boards.

These steps will efficiently loosen the grime, allowing you to pressure wash the stains away with more ease. Don’t forget to pay attention to areas that are hard to reach such as the corners and underneath steps. After this is done, then you can proceed to power washing.

About the author

Hey, I'm Dale Keese.. thanks for reading.. hopefully this article can save you some time and trouble with your sealing job. I'm also in the process of making some video walk-throughs for youtube so check back soon! thanks

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