Wood Balcony

How do you waterproof a wood balcony?

Waterproofing is typically a concern with wooden decks. The wood will absorb water, swelling and warping over time. The water can also degrade the wood or cause mould or mildew to grow, causing damage and health concerns. Applying a sealer is a common solution, but there are many options for waterproofing your decks depending on where the deck is located and how the deck was designed. Some methods are simpler than others, but all are useful.

Have you recently installed a new deck in your home or building, or have noticed that your deck is starting to show signs of wear and tear? If so, you must consider waterproofing. Wind, rain, and sunshine can all wreak havoc on your deck’s ability to withstand the elements, making it more susceptible to cracking and splitting from long-term exposure to water. Water damage can cause a wide range of issues to your deck, including slip and trip hazards, structural damage, and an overall undesirable aesthetic. But when is the best time to waterproof your deck? The answer: it depends.

Water, when combined with UV radiation and changes in weather and temperature, can cause your deck to look dull and weathered by washing away your deck’s finish, natural resins, and colour. While you can’t completely prevent your deck’s exposure to the elements, sealing your deck will help sustain its finish, which may save you time and money.

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The following factors will determine the best time to waterproof your deck:

Wood Balcony

The age of the deck 

If your deck is brand new, your wood likely still has a certain level of moisture and will not absorb a sealant until it has completely dried out. Depending on the type of wood your deck is made of, you may have to wait anywhere from three months to a year for the fibres in the wood to open up. If your deck is older, you should consider resealing your deck every 12 to 18 months.

The season

Many sealing products work best in certain temperature ranges. Sealing projects typically require between two to four days without rain and temperatures below 85 degrees Fahrenheit to ensure the stain and seal can be evenly absorbed and dried.

The weather

In addition to the actual process of applying the sealant, a deck must also be cleaned to remove the dirt and get down to the solid wood. Between cleaning and sealing, you will need to have a period of at least two to three days to allow the deck to dry out. In total, you will generally need a period of five to six days of clear weather.

How to Waterproof Decks


No matter what method you use, it’s important to prepare your deck properly, you can do it yourself or hire a contractor. Inspect your deck for loose, creaky or warped boards, then repair or replace them. Sand the deck, as well, especially if it is old or was treated with a sealer in the past. Having a smooth surface is essential and removing any sealer as much as possible is necessary for adding new waterproofing materials. Wash away all dirt with a deck cleaner, power washer, or both in combination. You must remove all dirt, mould and mildew. Deck cleaner will help restore the appearance of the wood and remove mildew and stains, such as rust from nails, but is hazardous and should be used with caution. The deck should be dry before using any waterproofing method.

Water Sealer

Wait for several days after cleaning a deck before applying water sealer. It’s important to work on a dry day, as well and better if it will not rain for several days after you apply the sealer. Applying water sealer is relatively simple. Stir the sealer thoroughly with a paint stir stick, then apply to the deck with a long-handled paint or stain pad or a roller with a long handle. Coat one or two boards at a time and go along the length of the boards rather than the width to avoid lap marks, which will show where you applied sealer in an unattractive way. Use a paintbrush to get sealer into corners. You can use multiple coats if desired.

Waterproof Membranes

Some companies produce vinyl membranes designed to apply over decks. The advantage of this is that the area below the deck will be dry, and water will run off the edges of the deck only. This is particularly useful for rooftop decks or elevated decks, the underside of which you may want to use as storage. You can also purchase EPDM sheets for the same purpose. With vinyl, you may need a professional to apply the sheet for best results. With either method, you can cover the membrane with decking tiles. Decking tiles are usually elevated slightly to allow water to run through and to the waterproof coating underneath. While decking tiles vary, many are designed to snap together as a floating floor with no adhesives, nails or grout required, making this part of the process perfect for a do-it-yourself project.

Rubberized Coatings

If your deck is made from plywood, you may want to consider waterproofing it with an elastic or rubberized paint. These paints both repel water and provide some extra safety in that they are not slippery. Application is much like that of regular paint. Stir the product thoroughly with a paint stir stick, pour some paint onto the deck, then spread it with an ordinary paint roller. Depending on your product, you may need a primer and a topcoat for the best result. You can also add decking tiles over a painted deck, as you may find the colour of the paint unattractive.

Waterproof Your Deck

Step 1: Check Your Deck  

Here are a couple of tests you can perform to see if your deck needs waterproofing. Drop several drops of water onto the deck. If the water beads up, the deck is still protected and doesn’t need to be waterproofed now. If a drop soaks into the wood, it means the old finish or waterproofing layer has worn away leaving the wood unprotected. You can also firmly press a piece of tape against the surface to be stained. The presence of old stain or wood fibres on the tape could indicate a potential moisture problem. Remove eroded wood fibres and loose stain by using a wood stripper then sanding and power washing the surface.

If your deck looks faded and grey, it’s time to refinish with some coats of stain. See the project, Stain Your Deck for more tips and information on how to finish your deck. All stains are waterproofing sealants as well, allowing you to stain and seal in one step. If it’s time to refinish your deck, consider using a quality stain, such as Woodsman.

Helpful Tips

Before you start staining or sealing, check your local weather report to be sure you’ll have at least 48 hours of dry weather.

All stains protect the wood from moisture, but some provide better protection from UV rays. Clear stains only protect the wood, while pigmented stains provide a higher degree of UV protection.

Also, check your deck for wood that’s worn out, splitting, twisting or rotting. If you see these signs, you will need to do more prep work and refinish the deck, before waterproofing.

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Step 2: Prepare the Deck for Waterproofing  

Before you start, remove everything from the deck, including furniture and potted plants. Loosely cover any delicate or fragile ground plants adjacent to the deck with tarps or drop cloths. Don’t use plastic sheeting on shrubs and plants. It can create a deadly “greenhouse effect” and harm your plants. Remove drop cloths from your foliage as soon as your project is complete, so they don’t suffocate. Sweep off loose debris with a broom and clean between the cracks using a slender stick or tool. Repair damaged boards and hammer in popped-up nails.

Use a garden hose or a pressure washer to spray the surface of the deck, forcing away dirt, dust, oil and grease. This will also help remove the top layer of previous waterproofing. Begin at one end of the deck and continue until you have rinsed the entire surface and removed as much dirt as possible. If you use a pressure washer, keep the pressure set to less than 1,000 pounds per square inch and leave a few feet between the spray nozzle and the deck to avoid damaging the wood. Set it to spray a fan of water, so it pushes dirt and debris away faster. Spray between the deck boards to eliminate any remaining debris. Use a pole sander or orbital sander with medium-grit sandpaper to smooth down any splintered areas and to remove remnants of the previous layer of sealant. Starting with as clean a surface as possible will help the new coat of sealant set in and provide a better level of protection.

Safety Alert!

When using a pressure washer, wear safety glasses to protect your eyes from splashing water and debris.

Cleaning your deck at least once a year helps it last longer and look better while maintaining the integrity of the wood. And when you’re planning on sealing or refinishing your deck, you’ll have to clean it first. Deck cleaning products are available in a variety of types and strengths. Some offer a special chlorine bleach formula for eliminating mould, mildew and algae. However, chlorine bleach formulas may require more frequent cleanings. Consider using a non-chlorine bleach cleaner instead, such as Woodsman® Premium Wood Cleaner.

Helpful Tip

The best outdoor temperature for cleaning and treating your deck is between 50 and 90 degrees Fahrenheit.

Make sure your deck is compatible with the cleaner you choose, especially, if your deck is made of softwood like redwood or cedar. Check the manufacturer’s instructions to see whether you should start with a dry or wet deck. Try to clean on a calm day to keep the wind from blowing the cleaning agent around the yard. Use a deck stain applicator to apply the cleaner to the entire deck. While applying, be careful not to allow the cleaner to puddle anywhere on your deck to assure an even appearance.

Scrub tough areas with a stiff brush or a broom. Don’t use wire brushes as wire bristles can break off into the wood and cause rust spots. Follow the product’s instructions regarding how long to let the cleaner soak into the wood, usually about 10 to 15 minutes. After the cleaner has been allowed to soak, rinse the deck thoroughly with a hose.

Safety Alert!

Cleaners contain bleaching agents, so wear protective clothing, safety goggles and rubber gloves.

After cleaning your deck, let it dry for at least 24 hours.

Step 3: Apply Sealant  

Apply a thin, even coat of high-quality, mould- and mildew-resistant, waterproof sealant with UV protection, such as Woodsman® Water Repellent or Woodsman® Wood-Toned UV Wood Sealer and Protector, using a stain brush, in the direction of the boards. Don’t forget to cover corners and other difficult areas such as steps, railings, board ends and cracks. Apply two coats if needed.

Safety Alert!

Wear protective clothing, safety goggles and rubber gloves when sealing your deck to prevent skin irritation.

Helpful Tip

Do not apply sealant in direct sunlight. It will dry too quickly without absorbing into the wood.

Step 4: Finish Up  

Stay off the deck while it dries, for at least 48 hours. Allow the sealant to dry completely before replacing any furniture and potted plants. When you’re finished, remove your drop cloths, return furniture and other items to your deck, clean your tools and enjoy.

That’s it! Your deck is sealed, waterproofed and ready for the winter weather ahead.

The Dos and Don’ts of Sealing the Deck

DO wait 30 days before sealing a new deck.

If you’ve just put in a new deck, you’re no doubt itching to finish the job by sealing it. But preservatives in the wood often require about 30 days’ dwell time before the deck can soak up the sealant. After 30 days, pour some water on your deck. If it beads up, the wood is still too wet to seal, but if the water is absorbed, it’s ready to seal. Be sure to apply a sealant as soon as the wood is ready; leaving the deck exposed any longer increases the likelihood of both ultraviolet (UV) and moisture damage.

DON’T confuse paint, stain, and sealant.

Sealant, stain, and paint can all be applied to a deck for different degrees of protection.

Sealants are primarily used to protect against moisture damage. They contain waterproof or water repellant properties and have a thicker viscosity than stains. Unlike stains, sealants lack pigmentation and generally provide less UV protection than stains.

Stains always include pigmentation, which adds colour to the deck and helps protect against UV damage. Even the best deck stains generally offer only moderate moisture protection.

Paint, be it latex or oil-based, can protect against both UV and moisture damage, but the best deck paint generally doesn’t hold up as long sealant or stain. Also, if there’s any lingering moisture in the wood during the application, the paint will be susceptible to bubbling and chipping.

Bottom line: A combined stain-and-sealant product offers durable, moisture- and UV-protection with the least drawbacks. Instead of that, you can apply a simple stain to the deck and, after 48 hours, apply a sealant for a similar level of protection.

DO repair, wash, and sand your deck before sealing.

Proper prep is key to successfully sealing a deck. Repair or replace any loose or broken boards, so that future breaks or cracks won’t create hazards. Then, wash the deck using a power-washer to scrub the surface clean. Allow to dry for 24 hours, then sand the surface with between a 60 to 150 grit sandpaper or sanding disk. Use a powered sanding tool to remove the top layer of wood, which could act as a barrier to the sealant.

On a previously stained deck, also be sure to sand the entire surface—areas where the sealant has worn away as well as those that still have moisture protection intact. This moisture protection would prevent new sealant from being absorbed, so sand evenly to ensure a clean, bare surface.

Finally, sweep or vacuum thoroughly. Even a brand new deck will need at least a brief washing and drying to banish any dirt and grime accumulated during the initial 30 drying period.

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DON’T apply a sealant to damp or frosty surfaces.

Applying a sealant to a damp or frosty deck will lead, at best, to an uneven, splotchy seal that can’t effectively protect your deck. At worst, the sealant will bead up on the water and fail to be absorbed, creating a messy, dangerous slipping hazard. Always allow the surface to dry for at least 24 hours after rainfall before sealing a deck.

DO use proper tools and technique for sealing a deck.

Deck sealant can be applied using a roller, a paintbrush, or even a paint sprayer. You can work from a standing position with a pole or on your hands and knees (kneepads highly recommended). Work slowly enough to ensure that every inch of the deck gets an adequate amount of sealant.

Overly thick sealant is prone to peeling and chipping, so avoid oversaturating the surface by applying only one coat of sealant at a time. In most cases, all you’ll need is one coat, but should you wish to apply a second coat, wait at least 24 hours.

DON’T disregard temperature and time of day.

Plan to seal your deck when temperature and time of day are ideal. Aim for a pleasant, not-too-windy day between 50 and 90 degrees Fahrenheit. Get to work in the morning, as the hot sun of a summer afternoon can cause the sealant to evaporate quickly, preventing adequate absorption.

DO apply a sealant-and-stain product once a year.

Consider this a general rule, depending on climate and the age of your deck. In sunnier regions, adhere strictly to a once-a-year schedule to protect the wood from powerful UV rays. Northern regions may get away with a two- or even three-year cycle; however, these regions are more susceptible to moisture damage, so be vigilant about sanding the deck before sealing to ensure that the sealant is able to soak into the wood to provide long term protection against melting snow and other moisture damage.

DON’T use the deck for 48 hours.

While sealant is normally dry to the touch within a few hours, for a proper seal that protects the wood, stay off your deck for two full days. To remind family members, put yellow caution tape across the access routes to the deck. After 48 hours, let the partying begin!

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Deck Waterproofing: Is It Worth It?

Taking proper care of your wood deck is extremely important. Because decks have direct contact with the outdoor elements, wood decks need to be properly sealed and waterproofed. If you haven’t sealed and waterproof your deck, we highly recommend you invest. If you have waterproofed your deck in the past, we have a few tips to help you gauge whether or not you’re due for some deck maintenance. Keeping up with the proper care required for your deck will lengthen its life significantly.

The standard rule for resealing your deck is once every year. However, the degree of wear and tear your deck gets can affect how soon you need to reseal. Not only that, but if your deck gets direct sunlight year-round, you may need to reseal more often to prevent it from becoming washed-out or discoloured. To test whether your deck is due for a new coat of waterproof sealant, pour a few drops of water directly on the wood. If the water droplets bead up, your deck is still protected from the elements. If it soaks into the wood, you are due for a fresh coat of sealant.

Once you’re ready to begin your waterproofing project, you will need to wash and prep your deck thoroughly — sand down any uneven or splitting wood, fill in any holes or imperfections and replace rotting planks. Then, with a scrub brush and bleach solution (3 parts water / 1 part bleach), scrub your deck in its entirety. After you’ve scrubbed out as much dirt as possible, power washes your deck to rinse away the chemicalsNote: If you have plants nearby or are worried about using harsh chemicals, you can forgo using bleach and scrub with warm water alone.

Apply waterproof sealant one coat at a time. Apply a thin coat of waterproof sealant (with UV protection) sealant with a stain brush. Make sure to stain in the same direction of the grain (and plank). Apply a second thin coat of sealant after the first has had some time to dry. Make sure your deck has at least 48 hours to dry before walking or arranging furniture on it.

You now have a perfectly prepped wood deck ready for spring showers Mother Nature might throw at you!

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