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Why is deck waterproofing a good investment for your property?

Deck waterproofing should be a part of your deck design right from the start and not an afterthought for this major investment in your property. 

You will be spending your valuable time and hard-earned money on a major feature addition to your building, and for most, there is a tendency to only focus on the look and purpose of your deck when talking with your deck contractor. 

What is deck waterproofing for?

The answer seems fairly obvious, that is, to waterproof your deck. The real question is what is the purpose of doing this task properly? 

The simple answer is longevity and durability. After making the decision to create this major add-on to your property, you’ll want to make sure that iit lasts as long as possible and remains in top condition.

What are the main benefits of waterproofing your deck? 

While waterproofing your deck properly ensures that your deck lasts a long time for you, your family, and your friends to enjoy, there are many other consequential benefits.

Let’s go through them. 


The first is safety. A wet deck, whether due to it being the border around a pool or simply open to natural elements can create rot in wooden features and elements, which is a huge problem if your entire deck is built out of wood. 

If you have metal features, you will want to make sure that these remain rust-proof and are free of corrosion, which can be incredibly important in a safety feature like a railing. 

This includes both sturdiness and of course not causing bodily harm and health scares with jagged rusty pieces.


The math is fairly straightforward. The less you have to repair, the less money you will spend. Although that is an obvious one, there are additional benefits to be had with a long-lasting and sturdy deck. 

If you want to expand, you can put your money elsewhere, both enhancing the value of your property as well as your enjoyment of your deck. 

Speaking of value, a well-built waterproofed deck or patio area can contribute to the assessed value of your home or property. 

Last, but certainly not least is insurance. The safer your home and the better quality deck you have, it will be reflected in any insurance costs affiliated with the property. 


Your time is valuable and if your deck is damaged, not only will you lose money on assessments and repairs, but you will be spending your time organizing assessments, and all the follow-through that the repairs will entail. 

This is time you could be spending chilling out solo, or with friends and family. There is also the time lost that you could have been enjoying your deck. 

So instead of basking in the sun during the summer with delicious food sizzling on the barbecue, you’ll either be finding somewhere else for your downtime or dealing with the damaged deck rather than enjoying your home. 

What are my waterproofing options for a new deck design? 

If you are in the planning stages of building the deck of your dreams and still working with your deck-building contractor, this is the perfect time to start talking about waterproofing your deck. 

You’ve got a lot of options, from materials to build with, to what to use with those materials to best maintain your deck and protect it. 

Waterproofing Materials 

Nearly all waterproofing systems can be divided into five basic categories. The first two are polymer-enhanced cement, and vinyl sheets or membranes, which are both most often used in residential applications. 

The others are urethanes (including polyureas), fiberglass, and composite systems based around self-adhered “peel-and-stick” membranes and are more popular when working on large, commercial projects. These materials are incorporated into the build from the get-go. 

Additional Waterproofing Systems

These include building under-deck drainage systems, applying flashing tape, adding rubber flanges, applying sealers or coatings, building in sleepers, and other additional waterproofing methods to better ensure the longevity of your deck. 

A good deck-building contractor will be able to work with you to assess which are your best options and then incorporate these features in the design and the build while talking you through future maintenance needs. 

Composite Decking 

Firstly, if you choose to go with composite decking, you’ve got most of your waterproofing built right in. Talk to your deck contractor about your options which include some brands that offer amazing products that won’t rot or warp and some also come with excellent warranties. 

However, keep in mind that nothing is 100% waterproof, and while incredibly low- maintenance, composite decking also needs a little attention and care. Adding rubber flanges underneath to stop water from running through to spaces underneath, and cleaning the surface will prevent mould or mildew, or even spore generation when soil sits on a wet surface for too long. 

Additionally, adding a clear, easy, spray-on water repellant with zinc oxide will further prevent mould and mildew from starting at all. Not to mention it will restore the look and colour of your deck and make it easier to clean.

What are my waterproofing options for an existing deck? 

If your pre-existing deck is made of composite, for example, getting a professional cleaning and then applying a good water-repellant spray will do wonders. 

If however, have a preexisting wooden deck and now want to focus on waterproofing, the primary options are using Sealers or Coatings. 


With wood boards, you will need to maintain and seal the wood properly and repeat this process every one to three years. The manufacturer guidelines on the sealant, the environment and weather, and the specifics of your deck materials will dictate this timeline. 

When applied the clear sealant will keep water from getting into the porous wood and therefore will reduce the risk of rot or damage. The water should bubble and sit on top of your deck similar to a well-waxed car. If you don’t see this then it is a good indicator that it is time to apply your sealer once more. 


Deck coatings are a thick substances that can be liquid rubber polyurethane, latex, enamel, acrylic or another material. It is used to resurface the deck to make it waterproof. 

Adding it requires cleaning the surface which makes it slip-resistant. It can be tricky to apply so if you can get professional help it is probably the best way to go, especially as an improperly applied coating can peel and needs adequate time to cure. 

Coatings can do a good job at masking cracks and splinters in wood decking, but some people feel the finish can feel gritty underfoot, which can make it difficult to get to places on the deck to repair them later including issues finding screws and other elements in the deck, and it is a slightly more expensive and time-consuming means of waterproofing a deck while still requiring the same periodic cleaning as sealers.

What else should I be thinking about when it comes to deck waterproofing? 

First things first, aside from your deck boards, waterproofing your deck substructure is key. The joists and beams used to hold up the deck are just as susceptible to damage and require equal care. Flashing tape is the most common answer. 

A non-skid, self-adhesive flashing tape placed over the tops of joists, rim joists, beams, and the ledger board can guard against expensive future costs associated with water damage.

The design of your deck is also going to play a role, as nowadays, people looking to maximize their space may include enclosed sunrooms, covered areas below stairs for multi-level decks and more. 

These require some thought to make sure you aren’t sitting underneath a dripping ceiling that’s meant to protect you from the weather while you still enjoy the outdoors. 


Utilizing sleepers which are pieces of wood used to raise the deck boards so that there is space underneath, allows the wood to “breathe” and minimizes water damage. 

This is a design often used for rooftop decks. However, these are also wood so the same care and maintenance need to be followed for the wood as the rest of your deck. 

Interlocking deck systems 

These include built-in water troughs meant to drain the water, pulling it away from the deck. However, there are a couple of things about this system that may be problematic for some people. 

The first is that it can be quite loud like rain on a tin roof, however, some people find that soothing, so that is a personal choice. The other is structural, however, and where the water drains from if it meets the house, for example against the ledger board, the water dump at that point can create its own problems. 

Under-deck drainage systems

These are waterproof gutter systems that are installed under your deck boards, preferably as an above-the-joist drainage system. This is ideal because it provides complete protection for all the joists and beams from moisture penetration.

Most people are so focused on how great their deck is going to look and how much they will enjoy it that they may overlook some of the potential aspects of a deck build like time and cost both immediately and down the line. 

Working with a certified deck-building contractor like MDT, especially in environments like Canada which can have both heavy rain and snow, can guarantee a beautiful and well-built deck. 

Aside from the fact that a deck building company has years of experience and can incorporate structural elements to ensure your enjoyment of your deck for a long time, they can also design an outdoor living space that can truly maximize your space. You could end up with an outdoor deck that exceeds your expectations!
Reach out to Mississauga Decks and Trim for an initial consultation today to see what we can do for you. From building a custom deck to waterproofing your deck, we’re here to help you build the backyard oasis of your dreams. 

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