8 things to know before putting a deck on a flat roof

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If you own a property with a flat roof, one of the best ways to increase outdoor space for your business, or to create a more attractive rental or condo property, is by creating an outdoor deck on top of a flat roof. When you add a flat roof covered deck to your business or property, you can then create beautiful outdoor spaces that can be used as an additional dining area, employee break area, or an outdoor common area with plants and seating for use by tenants, or yourself.

Simply stated, by putting a deck on a flat roof, you can beautify your property or business by adding to its enjoyment and value, and with the addition of plantings, you can be helping the environment. Our roofing company, Clinique de la toiture FCA located in Montreal, has been installing flat covered roof decks on commercial and residential properties in the areas of Montreal, Montreal North, Montreal East and Laval for over 20 years, and we are proud of the value we have added to properties throughout the area.

Of course, there are several steps to take when considering putting a deck on a flat roof. Our team of experts has created a list of “8 Things to Know Before putting a Deck on a Flat Roof”:


1. Inspect your current flat roof


To build a deck over a flat roof correctly, you first need to inspect your current flat roof. While many flat roof buildings have the correct support structures on which to install a flat roof covered deck, in some cases, additional structural work needs to be undertaken first to support the floating deck. In some cases, you may have what is called a warm flat roof, which means that the roof insulation is immediately underneath the roof membrane. When dealing with a warm deck flat roof insulation project, you may need additional supports installed first before proceeding with deck installation.


2. The venting must be working properly


If your flat roof is a cold flat roof – meaning the insulation is below the structure – while this may ensure that your flat roof has enough integrity and strength to hold your floating deck safely, you need to ensure that the venting is still in place and unobstructed so that the moisture that builds up naturally in the roofing can continue to vent after the deck is installed.


3. Think about the permit for the flat roof


Check with local building code experts on whether you require a permit to build your flat roof. In most municipalities, the safety of the flat roof is paramount. If you hire an experienced roofing company, then the company should work with the municipality on your behalf, to ensure that your roof is safe for its intended use.


4. Tips for the building


Then, once you have the required support and approvals for your flat roof covered deck, you need to build your deck from the bottom up. As water drainage can be an issue on a flat roof, you need to know that before you build a deck on a flat roof, you need to ensure adequate drainage by installing the correct flat roof membranes for decks. A properly installed roof membrane will ensure that your flat roof stays dry and sealed for years to come.


5. Get a professional company for the installation


Most flat roof membranes for decks are made of a highly durable, watertight installed material called EPDM. To ensure the most watertight installation, it is highly recommended you use a company that specializes in installing this material on a flat roof. Pooled water on a flat roof can cause structural damage over time, and a professional roofing company will ensure that your roof has enough angle to ensure proper drainage.


6. Maintenance and cleaning


Flat roofs also need regular maintenance and cleaning. As you create the plan to turn your flat roof into a deck, you need to make sure that you can remove the decking from time to time to inspect and clean the roof and keep it in prime condition.


7. Chose the right materials for the right look


At this point you are ready to put in your supports, and most floating decks are constructed using a variety of materials, such as “sleepers” (2×6 supports), pedestals or special composite decking materials that have been specially manufactured for such a use. There is a huge variety of materials available, and this allows the business or property owner to choose their own specific look and to meet their own construction budget.


8. Decorate as you like


Choose your materials and install your deck. Once installed, your deck should provide you many years of safe outdoor use with minimal maintenance. At this point, you can decorate and design your deck area to appeal to your own tastes. If you are a restaurant business, that may mean adding touches such as lighting and privacy screens for diners. In a residential building, you may want to add communal patio furniture or a barbecue area (check your area bylaws first!)

As you can see, there are a number of factors to take into consideration when putting a deck on a flat roof. In most cases – particularly if you are a business or property owner, this type of project is best left to the experts. The team at Clinique de la toiture FCA are experts in the design and installation of flat roof decks – we’ve been doing it since 1996. If this is a project you have been considering, then please feel free to give us a call at 877.280.4830, or fill out our online form, and we would be more than happy to help you with your project.


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