Waterproof Decks
Turn the space below your deck into a dry, usable outdoor living area.
A waterproof deck allows you to protect the structure above while transforming the space below into a functional extension of your home. At Royal Decks & Landscapes, we design and build waterproof decks as part of our custom deck construction services, helping homeowners make full use of their outdoor space in Toronto and across surrounding areas
Whether you’re planning a second-floor deck, protecting a walkout basement, or creating a covered outdoor seating area, waterproofing needs to be part of the design from the very beginning..
What Is a Waterproof Deck?
A waterproof deck is a deck system designed to control and manage water, not just on the surface, but beneath the deck as well. Unlike a standard elevated deck where rain and snow melt fall straight through the boards, a waterproof deck directs water away from the structure and the space below.
Waterproof decks are most commonly used on elevated and second-floor deck structures where the area underneath needs to stay dry.
Depending on the design and intended use, waterproofing can be achieved either at the deck surface itself or through a drainage system installed below the deck framing.
Why Waterproofing Matters in Toronto
Toronto decks are exposed to constant freeze–thaw cycles, heavy rain, snow accumulation, and spring melt. Without proper waterproofing, water repeatedly saturates framing, patios, and areas near basement doors and foundations.
Over time, this can lead to:
- Rotting deck framing
- Deterioration of patios and concrete slabs
- Moisture issues at walkout basements
- Reduced lifespan of the entire deck structure
A waterproof deck isn’t about adding complexity — it’s about protecting your investment and ensuring the space below your deck remains usable for years to come.
Waterproof Deck Systems We Use
There is no single waterproof deck solution that works for every project. The right approach depends on how the deck is built, what’s below it, and how the space will be used.
Our focus is always on design-first solutions, not one-size-fits-all products.
Under-Deck Drainage Systems
Under-deck drainage systems are installed beneath the deck boards and framing to capture and redirect water away from the structure. This allows you to keep traditional decking materials on top while creating a dry, protected space below.
These systems are commonly used for:
- Covered seating and lounging areas
- Walkout basement protection
- Outdoor living spaces beneath second-floor decks
When designed properly, under-deck drainage systems allow for lighting, ceilings, and finished surfaces without trapping moisture or restricting airflow.
Vinyl Deck Membrane Systems
Vinyl deck membrane systems create a fully waterproof deck surface by preventing water from reaching the framing below. Water is directed off the deck surface itself rather than passing through the structure.
These systems can be appropriate when:
- The deck surface must be completely waterproof
- Maximum protection is required below
- The design calls for a sealed, low-profile finish
Vinyl membranes are a specific solution, not a default choice. Proper slope, detailing, and installation experience are critical for long-term performance.
Integrated Waterproof Deck Design
The most important part of any waterproof deck isn’t the product — it’s the design.
Proper waterproofing starts with:
- Strategic beam and post placement
- Clear drainage paths
- Planning for ceilings, lighting, and finishes
When waterproofing is integrated into the structural design from the beginning, the system works with the deck instead of being forced onto it later.
What You Can Build Under a Waterproof Deck
A properly designed waterproof deck opens up real possibilities below, including:
- Covered seating and lounging areas
- Fireplaces and media walls
- Hot tubs and spa zones
- Outdoor kitchens and bars
- Dry storage and utility spaces
Waterproof decks are often paired with pool decks or walkout patios where moisture control is especially important.
Waterproof Decks vs Standard Elevated Decks
Not every elevated deck needs to be waterproofed. However, when the space below the deck matters, the difference is significant.
A standard elevated deck:
- Allows water to pass through freely
- Offers no protection below
- Limits how the area underneath can be used
A waterproof deck:
- Controls and redirects water
- Protects framing and surfaces below
- Creates usable, long-term outdoor living space
The key is deciding early whether waterproofing makes sense for your project.
Planning Matters More Than Products
One of the most common mistakes homeowners make is trying to add waterproofing after a deck is already built. While retrofits are sometimes possible, they are rarely as effective or efficient as doing it properly from the start.
When waterproofing is planned early:
- Structural elements are positioned correctly
- Drainage integrates cleanly
- Lighting, ceilings, and screens can be planned in advanceLighting, ceilings, and screens can be planned in advance
Frequently Asked Questions
Can an existing deck be waterproofed?
In some cases, yes. However, results depend heavily on the existing structure and access. Waterproofing is most effective when designed into a new deck.
Do waterproof decks require permits?
Permit requirements depend on deck height, structure, and scope of work. We help homeowners navigate permitting when required.
Will waterproofing trap moisture?
Not when designed correctly. Proper airflow and drainage are essential to long-term performance.
Is waterproofing worth the cost?
If you plan to use the space below your deck, waterproofing adds long-term value, usability, and protection.
Let’s Design It Properly
If you’re planning an elevated or second-floor deck and want the space below to stay dry, waterproofing needs to be part of the conversation early.
At Royal Decks & Landscapes, we design and build waterproof decks for homeowners in Toronto, Oakville, Mississauga, Burlington, and surrounding areas — with a focus on long-term performance and thoughtful design.
Contact us to start planning a waterproof deck that works from day one.
