What to Know About Deck Waterproofing?

Written By Adam Paul - Waterproofing Expert

The deck waterproofing is applying waterproofing membrane on the deck, deck ceiling, under the deck and deck parts in order to prevent water damage due to moisture, rain, and snow. You can use sheet membrane and liquid membrane for deck waterproofing. You should waterproof deck materials such as wood, plywood, composite, aluminum, and concrete. You can install waterproof deck materials such as vinyl, waterproofed aluminum, rubberized decking, and interlocking decking materials in order to prevent problems such as mold and mildew growth and slippering on the surface.

You can use EPDM, Vinyl, acrylic, and epoxy for deck waterproofing. The deck waterproofing membrane depends on the deck material. When you waterproof a deck, you should waterproof all parts of the deck, including the deck floor, under the deck (deck ceiling), deck rail, deck post and deck box. You should waterproof the decks at pools, rooftops, and balconies.

You can do deck waterproofing by using above the waterproofing membrane and using the below step-by-step process. When you waterproof a deck successfully, it will last long like this. Deck sealant for 1 to 3 years, deck stain for 2 to 5 years, deck waterproofing membrane for 5 - to 10 years, and deck paint can last 2 to 5 years.

You can protect the deck waterproofing by doing regular inspections, regular deck repairing, regular deck cleaning, not using harsh chemicals, and protecting from UV rays. If you do not protect a deck waterproofing it can be damaged due to thermal fluctuation, improper repairs and renovations, exposure to UV rays, Use of low-quality materials, lack of deck maintenance, inadequate deck floor preparation, and exposure to harsh chemicals of the deck.

What is Deck Waterproofing?

The deck waterproofing is applying waterproofing membrane on the deck, deck ceiling, under the deck and deck parts in order to prevent water damage due to moisture, rain, and snow. Deck waterproofing requires sheet membrane waterproofing for under the deck, deck ceiling and waterproofing stains for the deck floor, joists, posts, rails, and planks.

What Deck Materials You Should Waterproof?

You should waterproof deck materials such as wood decks, plywood decks, composite decks and aluminum deck concrete decks in order to prevent water damage on the deck floor, rail, post, and ceiling.

Wood Deck Waterproofing

A wood deck is an outdoor elevated platform made of wood that extends from a house or building in order to have extra space for living and activities. The most used woods for decks are cedar, redwood, and pressure-treated wood. The water impermeability of the wood is variable, depending on the type of wood used. When the deck wood is exposed to water it can rot, warp, or develop mold and mildew when it repeatedly gets wetting and drying over time.

To prevent wood deck damage due to water, you can apply a waterproofing membrane for deck waterproofing. You can use sheet membrane under the wood deck and a stain or waterproof sealant or coating for the deck floor, railings, and stairs. The stain waterproofs the wood deck by penetrating the wood fibers and sealing them against moisture. A wood deck rubber coating provides a waterproof barrier and also adds a skid-resistant surface to the deck.

Plywood Deck waterproofing

A plywood deck is an outdoor elevated platform made of plywood that extends from a house or building in order to have extra space for living and activities. Plywood consists of thin layers of wood veneer that are glued together. The most used types of plywood for decks are marine-grade, pressure-treated, and exterior-grade plywood. The water impermeability of plywood is varied with the veneer and glue type. When the plywood is getting wet it can delaminate, warp, or develop mold and mildew when it is wetting and drying over time.

In order to prevent plywood deck damage due to water, you can apply a waterproofing membrane on the plywood surface. You can use a sheet membrane under the plywood deck and a stain or waterproof sealant or coating for the deck floor, railings, joists, posts, and stairs. The stain waterproofs the plywood deck by penetrating the wood fibers and sealing them against moisture. A plywood deck rubber coating provides a waterproof barrier and also adds a skid-resistant surface to the deck.

Composite Deck Waterproofing

A composite deck is an outdoor elevated platform made of a combination of wood and plastic that extends from a house or building in order to have extra space for living and activities. The most used types of composite decking are polyethylene-based, polypropylene-based, and PVC-based composites. The water impermeability of composite decking is generally high due to the plastic component, but it can affect to water-related issues: develop mold and mildew, can fade or stain from constant exposure to water, or even warp over time.

To prevent composite deck damage due to water, you can apply a waterproofing membrane on the composite surface. You can use rubber flanges to fill the gaps to waterproof the underside of the composite boards. You can use DEFY extreme composite deck sealer for the compost deck floor waterproofing. You do not need to seal the composite wood deck surface once it is cleaned. If you properly seal, you can get extra years of use before your next cleaning.

Aluminum deck waterproofing

An aluminum deck is an outdoor elevated platform made of aluminum that extends from a house or building in order to have extra space for living and activities. The Aluminum deck is a water-tight outdoor living space. When you build an aluminum deck, you do not need underside waterproofing. Because the deck boards lock together under pressure to form a water-resistant joint, the top surface of the aluminum deck can be affected by the water. As a result of that, aluminum decks can be more slippery than other types of decks when it is wet.

In order to prevent the aluminum deck surface water effect, you can use aluminum deck waterproofing sealant LockDry® in order to prevent mold and mildew growth and improve skid resistance without harming the aesthetic view of the aluminum.

Concrete Deck Waterproofing

A concrete deck is an outdoor elevated platform made of concrete that extends from a house or building in order to have extra space for living and activities. Concrete is not a water-tight material. Hence water can penetrate into the concrete through its porus and it will build mold and mildew on the surface and make the surface more slippery. You can prevent this by applying a concrete waterproofing sealant, coating, and membrane on the surface by cleaning the surface.

What are the Waterproof Decking Materials?

Waterproof decking materials do not need a specific waterproofing layer on the deck. Because these materials are highly watertight and resistant to other types of water-related problems such as mold and mildew growth, and slippering, you can use the below materials as waterproofing decking materials.

1. Vinyl decking
2. Waterproofed aluminum decking
3. Rubberized decking
4. Interlocking decking tiles

What waterproofing membranes can be used for deck waterproofing?

When a deck is exposed to various weather elements, such as rain, snow, and sunlight, which can cause water damage and deterioration.

EPDM for Deck Waterproofing

EPDM (Ethylene Propylene Diene Monomer) waterproofing membrane is a type of high-performance, synthetic rubber sheet membrane that can be used for deck waterproofing.

EPDM membranes are installed under the deck in order to collect leaked water from the wood deck. EPDM is an excellent deck waterproofing membrane because it consists of heat, weather, and UV resistance, flexibility, durability, and minimum maintenance.

Vinyl for Deck Waterproofing

Vinyl waterproofing membrane is sheet waterproofing membrane that is made from a layer of PVC (polyvinyl chloride). Vinyl decking can be used to waterproof the deck of a building, offering a reliable and effective barrier against water penetration. The waterproofing characteristics of vinyl make it an excellent choice for decks, especially in areas with heavy rainfall or snow.

You can use vinyl as a deck waterproofing membrane because it is highly durable and resistant to wear, tear, UV, and water. Vinyl waterproofing is a slip-resistant surface that provides a safe surface when it is wet. Vinyl decking comes with different colors and patterns; hence you can improve the aesthetic view of the deck by using vinyl waterproofing membranes.

Acrylic for Deck Waterproofing

Acrylic is a liquid-type waterproofing membrane for deck waterproofing. Acrylic waterproofing is applied as a coating to the deck surface. It forms a seamless, flexible, and durable water barrier that prevents water from penetrating and causing damage to the decks.

Acrylic is a water-resistant, UV-resistant, flexible, and durable waterproofing membrane that can be applied on the decks by using a spray, roller, and brush on the deck.

Epoxy for Deck Waterproofing

Epoxy can be used as a deck waterproofing membrane. Epoxy is a liquid waterproofing membrane that can be used to waterproof the deck floor. Epoxy can be used for both wood and concrete deck waterproofing. Epoxy is a seamless, water-tight, durable material that is resistant to UV, water, and chemicals. Hence, epoxy can be used as a successful waterproofing membrane for deck waterproofing.

What Deck Parts You Should Waterproof?

You should waterproof wood deck parts such as deck floor, joists, posts, lumber, rail, and ceiling. For a concrete deck, you should waterproof the deck floor. For the composite deck, you should waterproof any traditional lumber. But, waterproofing is not essential for the aluminium deck.

Deck Floor Waterproofing

Deck floor waterproofing is applying a waterproofing membrane on the deck floor in order to prevent water damage and improve the water resistance and skid resistance of the deck. Wood decks, concrete decks, and composite decks need deck floor waterproofing. Aluminium decks also need deck floor waterproofing because deck floor waterproofing can improve skid resistance and prevent slippering on the floor.

You can use wood stain, sealant for the wood decks, waterproofing coatings, sheet membranes and waterproof paints for the concrete deck. For the aluminium and composite decks, you can use a waterproof sealer on the deck floor.

Under-deck (Deck Ceiling) Waterproofing

Under-deck waterproofing and ceiling waterproofing are the same kinds of tasks that are used to remove accumulated water on the deck floor.

Underside waterproofing is making a mini drainage system under the deck with a small inclination to the gutter channel. The drainage system under the deck is built by using a sheet waterproofing membrane. Sheet membranes are installed under the deck with the help of lumbers and joists. These sheet membranes below the deck accumulate the deck water with the help of downspouts and the inclination to the gutter.

At the end of the drainage, a mini gutter is built as a channel. A gutter channel is used to collect all the running water from the drainage system and take it away. You can use EPDM and HDPE sheet membranes for the under-deck waterproofing.

Deck Rail Waterproofing

Deck rail waterproofing is applying waterproofing membrane, coating, or sealant on the rail post, post cap, horizontal rail support, and top rail. Deck rain can rot, deteriorate, and grow mold and mildew on the rail surface when it gets wet over time. In order to prevent this you should waterproof the deck rail.

A deck rail is made with different kinds of materials such as wood, metal, and composite. Among them, wood deck rail should be waterproof by using a stain, waterproof coating, and waterproof sealant. Metal rails should be waterproofed using rustproof paint and sealant. But composite rail is not essential to waterproofing. It should be done if the wood parts are open to the wet.

Deck Post Waterproofing

Deck post waterproofing is installing waterproofing membranes on the post surface in order to protect the wooden posts of a deck from water damage. The common deck post water damages are rotting and decaying.

You can waterproof the deck post by applying a waterproofing sealant or stain to the posts. It's important to ensure that you should cover all sides of the posts, including the ends, cuts, and drilling holes. This process should be repeated every few years or as recommended by the product manufacturer to maintain waterproof protection.

Deck Box Waterproofing

Deck box waterproofing is applying water stain on the deck box in order to prevent water damage. The waterproof deck box does not allow to water penetration inside. Hence you can use it as waterproof storage in the deck. Most deck boxes are made of wood. Hence you can use stain, waterproof sealant, or costing on the deck box.

What Types of Decks Need Waterproofing?

You should waterproof decks that are subjected to heavy water impact. You should waterproof pool deks, rooftop decks, and balcony decks.

Pool Decks

A pool deck is an elevated area surrounding a swimming pool. The pool deck is constructed from concrete, wood, or stone materials. The pool deck can be damaged due to UV light, rainwater, chlorine water, and moisture. The most common water damage in the pool deck is mold and mildew growth, cracks and discolorations, water intrusion, and erosion and wearing.

In order to protect the pool deck you should apply a water impervious layer. The waterproof layer is varied with the deck pool materials. For the wood pool decks, you can use waterproof sealant, coating, or stain on the deck surface. You can use sheet membrane waterproofing on the concrete waterproofing. The applying waterproofing membrane should be resist to UV, water, and colonic water.

Rooftop Deck

A rooftop deck is an architectural feature that is designed to create an open, accessible outdoor space, typically on the top of a building. The rooftop is always open to the water and sunlight. Hence rooftops can be damaged by rainwater, snow, winds, and sunlight. The most popular rooftop water problems are water seeping into the structure, material deterioration, peeling paints, mold and mildew growth, and cracks on the deck.

You can waterproof the rooftop deck by using a sheet and liquid waterproofing membranes. Liquid waterproofing membranes are highly recommended for stable structures decks and high-windy areas with rain. Sheet waterproofing membranes are suitable for stability fluctuation decks and heavy rainfall areas.

Balcony Decks

A balcony deck is an elevated platform or structure that extends from a building. The balcony is enclosed by a railing or balustrade. Open balconies are always subjected to get wet and open to fresh air, sunlight, and moisture. Hence balcony water can seep into the building structure. In order to prevent this you should waterproof the balcony by using a sheet membrane or liquid membrane.

How to Do Deck Waterproofing?

Deck waterproofing is a process of laying a waterproofing membrane. To waterproof a deck, you should follow the 9 steps below.

1. Clean the deck surface: Start by cleaning the deck surface and removing dirt, debris, and any old materials on the surface. You can use a deck cleaner or a mixture of water and mild detergent. In this step, you can use a power washer.
2. Inspect and repair the deck surface: Inspect the deck for any damaged or rotten boards. Replace or repair them before proceeding with waterproofing. Ensure that the deck structure is in good condition.
3. Sand the deck surface: Sand the deck surface to smooth out any rough spots and create a better surface for the waterproofing material to adhere to.
4. Choose a waterproofing product for the deck: There are 3 options for deck waterproofing. Those are deck sealers, deck stains and waterproofing membranes. Deck sealers pvide a transparent finish and allow the natural wood grain to show. Deck stains add color to the wood while providing a waterproof barrier. Waterproofing membranes like rubber materials create a barrier between the wood and the elements.
5. Deck Paints: Offer a more opaque finish and come in various colors.
6. Apply the waterproofing material on the deck surface: Follow the manufacturer's instructions for the chosen waterproofing material. Typically, you'll use a brush, roller, or sprayer to apply the product evenly. Ensure that you cover the entire surface, including the edges and ends of the planks.
7. Let the deck surface to dry: Allow the waterproofing material to dry completely before using the deck. Drying times can vary based on the product and environmental conditions.
8. Apply additional coats on the deck if necessary: Depending on the product used, you may need to apply multiple coats for effective waterproofing. Follow the recommended drying time between coats.
9. Do regular deck maintenance: Regularly inspect your deck for signs of wear and reapply waterproofing as needed. The frequency of maintenance will depend on the type of product used and the weather conditions in your area.

How Long Does a Deck Waterproofing Last?

Deck waterproofing consists of deck sealant, stains, waterproofing membrane, and deck paints. Deck sealant can last 1 to 3 years. Deck stain can last long 2 to 5 years, Deck waterproofing membrane can last long, 5 to 10 years, and deck paint can last 2 to 5 years.

The durability of the waterproofing on the deck depends on the climate, sun exposure, food traffic, structural stability, maintenance, and quality of the application.

How to Protect Waterproof Deck?

A waterproof deck should be protected in order to keep the performance of the waterproofing layer. You can follow the below steps to protect the waterproof deck.

1. Do regular deck inspection: You should periodically inspect the deck for signs of wear, damage, or water intrusion. Check for any areas where the waterproofing may be compromised, such as peeling, cracking, or discoloration.
2. Do regular deck repair: You should do regular repairs If you notice any damage or areas where the waterproofing is compromised, make repairs as soon as possible to prevent further deterioration.
3. Do regular deck cleaning: You should clean the deck regularly to remove dirt, debris, and other contaminants. You can use a mild detergent or a cleaner recommended by the waterproofing product manufacturer.
4. Do not use harsh chemicals on the deck: You should be careful not to use any harsh chemicals on the deck because can degrade the waterproofing material.
5. Protect deck from UV rays: You should apply UV resist coating or sealant If your deck is exposed to direct sunlight.

How to Damage a Waterproofed Deck?

A waterproof deck can be damaged due these 7 reasons such as

1. Deck stability fluctuation: When the deck stability fluctuates due to external forces, the waterproofing membrane can be damaged easily.
2. Deck Repairs and Renovation: When you cut and drill on the deck floor for renovation projects, the deck floor can be damaged with the waterproofing layer.
3. Exposure the deck to UV rays: When the deck is directly open to the sunlight, the waterproofing layer can be damaged
4. Using low-quality materials for the deck waterproofing: With an aging deck, waterproofing can be damaged due to using low-quality materials because Low-quality waterproofing materials reduce the strength of the waterproofing layer.
5. Lack of Deck maintenance: Deck waterproofing membrane can be damaged due to a lack of regular maintenance and inspections.
6. Inadequate deck floor preparation: A deck floor waterproofing can be damaged due to inadequate floor preparation. When you apply the waterproofing layer on the dirt and loose material, its bonding can be reduced.
7. Deck exposure to harsh chemicals: When the deck is exposed to harsh chemicals, such as certain cleaning agents or pool chemicals, it can degrade the waterproofing layer.