How to Waterproof a Deck

Anyone who has an outdoor deck wants to be able to enjoy it for many years. To keep the deck in top shape, it’s important to inspect it and keep it weatherproof.

Waterproofing your deck requires some prep-work as well as optimal weather, so you’ll want to plan accordingly. Once your deck is prepared, the sealing process that ensures weatherproofing will take about two days. After that, your deck is ready for use again!

Pre-Sealing Considerations

  • You’ll want to research if you want to paint, seal, or stain your deck.
  • Know that everything needs to be completely removed from your deck beforehand and other nearby plants and items will need to be covered.
  • Keep an eye on the weather beforehand because you can’t weatherproof your deck when it is rainy or if it is too hot and sunny.
  • Make sure you have all of your tools and protective gear before starting the project.
  • Plan to spend up to four days on the weatherproofing project from start to finish.
How to Waterproof a Deck

Inspecting Your Deck

Before starting, you’ll want to give your deck a once over. Some key things you are looking for are if the deck needs boards repaired before starting the sealing process. If they need to be nailed back in, or if they are starting to show signs of rotting or tearing, you’ll want to fix those things before coming in with the waterproofing sealant.

Sometimes it’s as simple as re-affixing the boards. Sometimes you will need to call a mold or termite specialist to inspect the deck. If the deck has been well-cared for previously, you may not need to worry about these things.

Testing the Deck

You don’t want to do a whole waterproofing job and then find out that your deck still has good waterproofing on it. One quick way to test is to drop some water on it. If the water bubbles and stays on top of the wood, you won’t need to re-seal just yet. But, if the water gets absorbed by the wood, you’ll want to re-seal.

If you don’t want to do the water test, you can also stick a piece of tape to the wood. When you peel the tape back off, a clean piece of tape means the sealant is still good, but wood fibers mean you’ll need to put down a new coat.

Prepping Your Deck

This is probably the most crucial part. If you don’t prepare your deck properly, all your work will be for nothing! Some things you’ll need to do:

  • Sand the wood down to remove any uneven grain and previous staining.
  • Pressure wash all surfaces with either a pressure washer or a high-powered garden hose attachment.
  • Ensure you’ve removed all debris between wooden planks.
  • Use a deck cleaning solution to remove any stubborn grime.
Westinghouse Pressure Washer

Westinghouse Pressure Washer


  • Power Source: Gas Powered.
  • Item Dimension: 21 x 19.5 x 39 inches.
  • Maximum Pressure: 2700 Pound per Square Inch.

Applying the Sealant

You’ll want to wait at least 24 hours between washing the deck and applying whatever sealant or stain you have chosen. Once it’s all dry, use a paintbrush, roller, or a paint sprayer that can be used with stains and sealants to apply a coat to all visible portions of the deck.

Don’t apply a super thick coat because then it will get sticky and might never cure properly. Two light-to-moderate coats work best. Some sealants recommend more than two coats for best waterproofing results, so be sure to check the instructions on the label.

You’ll want to start on one end and apply methodically so nothing gets missed or becomes uneven. Always apply with the grain of the wood if you are using a brush or a roller.

If the sealant is pooling in places, you can go over it with a wool pad in small circles to better distribute it.

Precision Defined Roller

Precision Defined Roller


  • Guaranteed no fuzzies. Get the job done better and faster with our 9-inch roller covers.
  • Designed to hold and release paint evenly and uniformly for that smooth and velvety finish we all love.
  • Our paint roller covers offer you the best quality there is.
Wagner Paint Sprayer

Wagner Paint Sprayer


  • The Control Pro 130 Power Tank applies coatings 3X faster than a roller with low overspray.
  • Produces up to 55% less overspray than traditional airless sprayers which means easier preparation, quick clean up, and less paint or stain used.
  • The Power Tank airless sprayer can be used with a wide range of unthinned paints and stains for interior/exterior jobs.

Letting the Sealant Cure

Check the instructions on the stain or sealant, but most will allow a second coat eight hours after the first. Some will allow second coats in as little as two. Depending on how big your deck is, you can start applying the second coat right after you’ve done the first coat, just working on the same sections in order.

Once both coats are applied though, you’ll need to wait 48 hours minimum for full cure.

Just because the sealant looks dry does not mean it is. Try not to walk on the deck or otherwise touch the deck until those two days have passed. If you scuff the sealant now, you’ll have to start back at the sanding step or risk the deck not being properly waterproofed.

Setting Your Deck back up for Enjoyment

Once everything has dried and the job is done, you can put all your furniture, plants, barbeques, and whatever else you had on your deck back out. You can enjoy your waterproof deck to the fullest extent possible.

Now you can enjoy your deck for several years without thinking about doing this whole process again. Many products say they’ll last for ten years, but even the ones that last for five mean you have less to worry about for the oncoming summers.