How to Waterproof Your Deck Before Installing Pavers or Tiles
A deck is only as durable as the structure beneath it, and while pavers and tiles might look the part, the real longevity of the installation depends on whether the surface is properly protected from water damage. The majority of problems that occur with outdoor decks are the result of water seeping through the layers, leading to issues like mold, mildew, rot, and even structural weakening over time.
By pairing a high-quality waterproofing approach with a stable support system such as the Outdoor Floor System®, you can create a deck surface that is not only attractive but also built to last. In this guide, we’ll walk through the process of preparing and waterproofing your deck before installing pavers or tiles.
Why Waterproofing is Important
Decks are constantly exposed to the elements and all forms of weather. Because of this, it's very easy for water to work its way into the underlying structure. Even a regular cleaning routine could lead to moisture inside the deck if it hasn't been properly waterproofed. Over time, this moisture can cause damage that is ultimately difficult and expensive to repair.
Waterproofing helps by creating a barrier that keeps moisture away from the substructure. This not only protects the deck framing and joists but also extends the life of the finished surface. When combined with a floating support system like the Outdoor Floor System®, water can drain away freely under the pavers or tiles instead of getting trapped against the surface. This design minimizes long-term maintenance and helps ensure that your deck performs well for years.
Planning and Preparation
Before you begin waterproofing, take a close look at your existing deck surface. The underlying structure must be in good condition, as waterproofing alone cannot fix serious damage. Replace any rotting boards, tighten loose screws, and make sure the deck is stable.
Measure the total area you plan to waterproof. Knowing your square footage will help you calculate how much waterproofing material you’ll need. Decide whether you’ll use a liquid membrane, sheet membrane, or another waterproofing solution, depending on your deck’s size and condition.
Finally, consider how the finished space will be used. Will you install porcelain pavers, composite tiles, or natural stone? Knowing this in advance helps you choose the best combination of waterproofing products and support systems.
Materials and Tools
For this project, you’ll need:
- A waterproofing product (liquid-applied membrane, roll-on membrane, or sheet system)
- Primer, if recommended by the manufacturer
- Outdoor Floor System® supports and framework
- Pavers or deck tiles for the finished surface
- Application tools (paint rollers, brushes, trowels, or sprayers)
- Caulking for joints and flashing for edges
- Safety equipment (gloves, goggles, knee pads)
Having everything on hand before you begin makes the process smoother and avoids interruptions once the waterproofing is underway.
Step One: Cleaning and Preparing the Deck Surface
The very first step is to make sure that your existing deck is cleaned and dried. This means sweeping away any dirt on the surface, and using a pressure washer or stiff brush to remove stains if necessary. The surface then needs to be completely dry, as any moisture could prevent the waterproofing products from being able to bond properly to the surface.
Whilst you are cleaning, take some time to look closely at the surface for any gaps where water could seep in through. You should look out for things like cracks in the material or gaps between panels. Where possible, fill these with a sealant that is compatible with the material and allow them to fully dry. You should pay special attention to the corners of the deck and any seams or transitions around posts and railings - these are the most common weak spots.
Step Two: Applying the Waterproofing System
Once the deck is clean and prepared, you can begin applying your chosen waterproofing product. Follow the manufacturer’s instructions carefully.
For liquid-applied membranes, you can use a roller or brush to apply an even coat across the entire surface. You should take your time and work methodically, going from one end to the other, and overlapping your strokes slightly so that you don't accidentally create gaps. Some products will require you to apply multiple coats, but make sure that you leave enough time for each layer to cure fully before you start applying the next one.
If you're using a sheet membrane, roll it out carefully and press it firmly onto the surface, sealing the edges with adhesive or flashing tape. As you go along, make sure to smooth out any air bubbles so that there is full contact between the membrane and your deck.
No matter which product you choose, take your time around edges and seams to prevent leaks from happening later on.
Step Three: Allowing for Proper Curing
Waterproofing systems need time to cure before you install anything on top of them, and depending on the product, curing can take anywhere from 24 hours to several days. Avoid walking on the surface during this period, and keep it free from dust, leaves, or moisture.
Skipping this step can compromise the waterproofing and shorten the life of the entire installation, so be patient and give the product the time it needs.
Step Four: Installing the Outdoor Floor System
Once the waterproofing has cured, you’re ready to create the support structure for your pavers or tiles. This is where the Outdoor Floor System® makes a big difference.
Traditional installations often bond pavers or tiles directly to the waterproof surface, which can trap moisture and lead to failures. The Outdoor Floor System® avoids this problem by creating a floating platform above the waterproof layer. Adjustable pedestals and framework keep the surface level while leaving space beneath for water to drain freely.
Begin by laying out the pedestals in a grid pattern across the deck. Adjust their height to achieve a consistent, level surface. Then place the structural panels or framework on top, securing them as recommended. This creates a stable base for your pavers or tiles, without ever compromising the waterproofing underneath.
Step Five: Installing Pavers or Tiles
Now that the support system is in place, it is time to start installing the surface material. Whether you’re using porcelain, stone, or composite deck tiles, the Outdoor Floor System® locks them securely into position while maintaining even spacing for drainage.
Start from a visible edge or corner and work your way across the deck. As you go, check that each row is aligned and that gaps remain consistent. Use a rubber mallet to tap tiles gently into place if needed. At the edges, you should cut the tiles to fit using a tool that is suitable for the material. You must always wear protective equipment when you are doing this, and double-check all of your measurements before making irreversible cuts.
Step Six: Securing the Perimeter
Once all tiles or pavers are in place, you can secure the perimeter. Trim pieces or edge restraints can be added to keep everything locked in position and to prevent lateral movement. This final detail not only improves stability but also gives the deck a finished and professional appearance.
Step Seven: Final Checks and Touches
Once you're done, the last step is for you to walk across the surface and check that it feels both level and stable to you. If you're happy with an area, you can simply adjust the pedestal heights. As you go along, also check for any loose tiles and correct them as needed.
And that's it, you're done! You can now add your furniture and outdoor accessories to make the space feel like part of your home. Because the system is modular, you can easily lift and replace the tiles in the future if you decide that you want to refresh the look, or if you need to access the waterproofed surface underneath.
Maintenance Tips
A waterproofed deck built with the Outdoor Floor System® is low maintenance, but it’s still worth giving it some attention over time. Sweep regularly to keep debris from building up, and wash with a mild detergent as needed.
Once or twice a year, lift a few tiles and check the waterproofing membrane below. Confirm that it’s intact and dry, and address any small issues before they become larger problems. Because the system is floating, it’s easy to inspect and maintain the waterproofing without disturbing the entire surface.
Safety Considerations
When you work with waterproofing products, you must always follow safety instructions. This usually means wearing gloves and googles, and making sure that your area is well-ventilated (though this should be the case anyway if you're installing outside). Always take care when you're lifting heavy pavers, and use the correct cutting tools to prevent accidents from happening.
Finally, always take the time to check that your deck is structurally sound before you start working. Waterproofing protects against moisture and future damage, but it does not reinforce a frame that is already unsafe.
Conclusion
Waterproofing your deck before installing pavers or tiles is one of the most important steps in creating a long-lasting outdoor space. With the added stability and drainage of the Outdoor Floor System, you can protect the underlying structure while enjoying a finished surface that looks beautiful and performs well.
If you're willing to put the time in to prepare and waterproof your deck correctly, you'll have a space that can withstand the elements for many years to come.
