How to build a roof deck

Had a sudden urge to enjoy the view from the top of your building and decided to install a deck on your roof?

Not so fast!  Did you know that building a roof deck is a complex and time-consuming process?  In fact, if you want to achieve a satisfying result that fully complies with applicable regulations, you should probably do some research, especially with roofing specialists and your municipal government. In addition, since roof decks are built at heights, you’ll need to pay special attention to work site safety. In short, you shouldn’t jump into this kind of construction project blindly.

The best thing you can do to prepare for building a deck on your roof is to read this article by our certified Montreal roofers. There are several things you need to know before you begin your work.

Define the function of your roof deck

Before you even think about applying for a building permit or purchasing materials, you should determine exactly what your future roof deck will be used for.

In fact, there are different types of roof decks you can choose from.


This type of roof deck is generally the simplest and least expensive to build. Once the required structural modifications to your flat or pitched roof have been made, you simply build a deck with adequate drainage. Treated wood is a very popular material for this type of rooftop deck.

Green roof

Green roofs are becoming more and more popular, especially in the city, as they allow you to enjoy an oasis of greenery and coolness on your roof. In addition to countering urban heat islands, adding greenery will enhance the scenery! Why not take advantage of this opportunity to innovate by creating your own urban garden? The possibilities are endless so be creative!

However, given the additional weight that this type of roof deck carries, it is critical to have a flat roof inspection done to make sure that your building’s structure is strong enough to support it.

Furthermore, planting vegetation on a roof often requires the installation of high-performance flat roof membrane and drainage systems to prevent water infiltration.

Find the dimensions of your roof deck and develop a plan

Among other things, determining the surface area of your rooftop terrace will help you decide on the feasibility of your project with your municipality’s urban planning department and obtain the required permits.

As a guide, some localities will require that your roof deck be set back from the front of your building. Others may refuse to let you build a deck if it extends more than two metres above the roof of your property.

When designing your future deck, there are many details to consider. For example, loads must be distributed properly and snow or ice build-up must be anticipated because it can add a lot of weight to your roof.

We recommend hiring a roofing contractor to design the plans to prevent design errors. A roofing expert will not only facilitate the design of the plans and the issuance of specifications for your roof deck but will also be able to advise you on the standards and regulations applicable to your area.

Choose appropriate and high quality materials

When choosing the materials to build your roof deck, you should consult with roofing professionals that offer flat roof services.

As an example, they will take into account the requirements for non-combustibility of materials, in order to limit the spread of fire.

You should also try to choose high-quality materials (elastomeric membrane, vapour barrier, treated wood, etc.). The long-term durability of your deck is at stake here, as well as the safety of those who will be enjoying it on sunny days!

Important points for the installation of a flat roof

Although solid, the roof of a building or a house is still vulnerable. Altering its components will make it susceptible to bad weather, temperature variations and much more. As such, building a deck on top of a building will inevitably add weight to the structure, which could weaken it. Similarly, the screws, nails and tools used to assemble the deck can damage the roof covering, which can cause flat roof leaks.

For these reasons, leave the installation to experts. They will be able to take these aspects into account and determine the steps to follow to avoid deteriorating the siding and distribute the weight properly. They will also see if it is necessary to add rubber supports to shore up the construction.

Regulations and permits for building a roof deck

As mentioned above, municipal by-laws and standards for roof decks differ from one municipality to another. They may also vary depending on the elevation and visibility of the structure, the purpose of the building and its location.

Note that buildings located in certain zones, or where the land or property is considered to have heritage value, are likely to have these constraints tightened for the installation of a rooftop deck.

For more information on this topic and to determine the criteria met by your property and its possible installations, consult our experts or visit the website of your borough.

Making sure your flat roof construction project is safe

In addition to posing certain technical difficulties, this type of work is carried out at height. This implies considerable safety risks not only for the workers, but also for the passers-by and the occupants of the building.

For this reason, it is crucial to hire certified flat roofers to help you build your roof deck. They will establish a safety perimeter, take care of accident prevention and ensure proper waste disposal.

Finally, in addition to looking after their own safety when working at height, roofing experts can also ensure the safety of your family and friends. They will be able to install the necessary fall protection, such as ramps or guardrails, when required.

Trust Les Couvreurs Duro-Toit to build your roof deck

In conclusion, even if you have some experience in construction projects, building a roof deck should not be taken lightly. To make sure you don’t overlook anything when building your roof deck, ask our team for advice.

And if you’re looking for a company that can offer you a turnkey approach, we can also meet your needs. Request a free quote now and your dream of basking in the sun and BBQing on your roof could become a reality sooner than you think!


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