How to Build a Rooftop Terrace

Doesn't the idea of a rooftop terrace sound lovely? Of course it does and as a result, this project is becoming more and more common. This outdoor area can be turned into a pleasant and unique space for socializing and enjoying the sun.

However, before you launch this major renovation project, it's necessary to determine specific rules and techniques for the job. So look no further, as we've got some crucial information and a few tips on how to carry out your rooftop terrace project while keeping within a controlled budget.

Starting points for building a rooftop terrace

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The idea of a rooftop terrace is appealing for multiple reasons. Who doesn’t love the idea of enjoying a bit of sunshine with a drink in hand surrounded by family and friends? Of course, this project may be easier said than done. There are several considerations that need to take place before diving headfirst into this project. Ask yourself these questions:

• Can your property roof and walls handle the weight of a terrace? This includes how it’s furnished, finished and with the weight of people on it.

• Is a major reconstruction required? If your roof is slanted, major reconstruction will need to happen before you can build a terrace. Sloped roofs can be adjusted by building an external wall or cutting directly into the roof. If your roof is flat, the same needs and considerations will not be required.

• Lastly, how do your neighbours feel about this project? In some municipalities, you may not be allowed to build a rooftop patio at all. If it is going to overlook their property, it will infringe on their privacy or could affect their skyline. Check with both your neighbours as well as local building codes to determine if you can move forward with this project in an amicable manner.

Do does the project require a transformation permit?

In many cities and municipalities, setting up a rooftop terrace requires a transformation permit. It is recommended that you contact your local authorities to know which permits are needed for your project and the rules that apply alongside the permit. For example, in Montreal, the terrace walls cannot exceed two meters in height. Further, the terrace needs to be placed a few meters away from the building façade. Lastly, the terrace must be set up at least 1.2 meters away from the property limits. These elements are of extreme importance and the failure to apply for the right permits can lead to legal recourse, so do your homework. 

How to determine the technical constraints to installing a rooftop terrace

It's highly recommended that you hire an architect for this type of endeavour, especially if it's going to come down to major roof reconstruction. An architect will calculate the load-bearing capacity of your roof and this will determine whether or not the rooftop terrace project is doable. For example, if you want to set up a garden on your roof, you will have to take into account the extra weight created by the wet soil, an aspect which might affect the size of the garden.

Respecting the weight limits will also affect the strategic choices concerning the materials that will be used for the staircase. Indeed, an aluminum staircase is much lighter than a steel staircase but it costs three times the price. As mentioned, be sure to consider the fact that you might have to turn your roof into a flat roof or that you might need to strengthen the current surface. There are a few cost-effective solutions, like pressure-treated wood posts which are installed on a styrofoam base.

Photo: Houzz

Budget for building a rooftop terrace

Investing in such a major renovation is not a trivial thing and serious consideration must be given to the budget of this project. To start, you should be aware that you'll likely spend upwards of at least $15 000 for this type of project. However, just think of the benefits! Your quality of life will improve, as the addition of a safe haven will make you feel like you’ve travelled outside of the city for a moment. If you have a limited budget, you will probably opt for a rooftop terrace made of wood.

With this type of setup, once the building’s structure has been modified, the next step will be to install a floor and a draining system. If your budget allows you to do so, you can opt for a rooftop terrace with white gravel, but if the building isn’t already equipped with a white membrane, one will have to be put in.

Ultimately, the most expensive rooftop terrace is the type that includes a membrane and layers of vegetable substrate. Building a terrace on your roof is not an easy thing to do but it is a worthy investment as this type of project adds a lot of value to a house and will be a great selling argument.