Do you dream of a beautiful outdoor space to enjoy the summer? Building a terrace or patio in Longueuil isn't just a matter of installing boards or pouring concrete. Between the Montérégie's clay soil, intense freeze-thaw cycles and precise municipal bylaws, you have to know what you're doing.

At Cartago Construction, we build terraces and patios on the South Shore for over 10 years. We know the challenges of the territory, the requirements of the Ville de Longueuil and the materials that will stand up to our winters.

This guide covers everything you need to know before starting your project. We talk about permits, materials adapted to the Quebec climate, realistic costs for 2025-2026 and mistakes to avoid. No fluff, just concrete information to help your project go smoothly.

Terrace or patio: what's the best option in Longueuil?

This is often the first question we're asked. The difference between a terrace and a patio starts with the height and structure.

A terrace is elevated. It's built on a deep foundation, often with a wood or steel structure, and is usually at the same height as the house's patio door. A patio, on the other hand, is at ground level. It is built directly on a base of compacted gravel, concrete or interlocking paving stones.

Your choice will depend on your terrain, budget and intended use. Both options have their advantages, but they also have their constraints to consider. Longueuil.

Raised terrace: when and why to choose it

A raised terrace is the ideal solution if your land is on a slope, or if you want direct access from inside the house without steps.

It also offers a better view of the garden and creates a true extension of your indoor living space. In Longueuil, many lots in Vieux-Longueuil or near Michel-Chartrand Park have natural slopes that lend themselves well to this type of construction.

However, as soon as your terrace exceeds 0.6 metres (about 2 feet) in height, the Ville de Longueuil requires a permit. You'll also need to install an RBQ-compliant guardrail if the height reaches 0.9 metre or more.

In terms of foundations, screw piles are preferred to avoid frost heave. More on this later.

Patio floor: concrete, paving stones and stability

A ground patio is less expensive and often quicker to install than a raised terrace. If your land is relatively flat and you're looking for space to install a garden furniture set or a BBQ, this is an excellent option.

In Longueuil, clay soil poses a major challenge. Clay swells when it absorbs water and contracts as it dries. This creates movements that can crack concrete or cause interlocking paving stones to sag if the base is not well made.

For a concrete patio, we recommend a minimum thickness of 4 inches with wire mesh, laid on a 6- to 8-inch compacted gravel base. For interlocking paving stones, soil preparation is even more critical: excavation, geotextile, gravel, polymer sand and multi-stage compaction.

Drainage is really crucial. Always install a slight slope (about 2 % of incline) to keep water away from the house. Without it, you run the risk of water seeping into the house. basement.

What Longueuil's climate and soil demand of your project

Building a deck or patio in Longueuil is not the same as in California or even British Columbia. Our climate and our soil have particularities that can't be ignored.

If you skip these steps or follow generic advice found online, you're going to have problems in 2-3 years. Cracks, settling, buckling boards. We've seen it all before, when we're called in to fix poorly done work.

Freeze-thaw and heave: the main enemy of terraces

The freeze-thaw cycle is the worst enemy of outdoor structures in Quebec. In winter, the ground freezes solid. Water in the soil turns to ice, and ice takes up more space than liquid water. As a result, the ground swells and pushes upwards.

In spring, everything thaws and the ground sinks again, but rarely uniformly. It's this repeated movement, year after year, that causes poorly anchored foundations to heave.

In Longueuil, the frost line is around 1.2 to 1.5 metres deep, depending on the area. This means that all your foundations - piles, concrete footings or pillars - must go below this line to be stable.

If your foundations are too shallow, your deck will literally rise in winter and fall again in spring. After a few cycles, the structure will warp, the boards will split and the railings will move. It's not safe, and it's going to cost you dearly in repairs.

Why auger-installed piles are the preferred choice in Montérégie

Screw piles have become the standard for decking in the Montérégie region. It is estimated that 70 to 80 % of new terraces in the region use this type of foundation.

Why? Because they go down below the frost line (we install them at a minimum of 1.2 metres) and are screwed directly into stable soil. They are resistant to heave and adapt well to the clay soils found throughout Longueuil.

What's more, installation is quick and clean. No need for major excavation or pouring of concrete. An experienced team can install piles for an average terrace in a single day.

The cost is a little higher than traditional concrete piers, but the long-term stability is well worth the investment. We're talking about 100 to 150 $ per pile installed, depending on the depth and accessibility of the site.

At Cartago Construction, we work with certified screw pile suppliers to ensure that each installation meets the structural loads required for your project.

Permits and regulations in Longueuil: what's mandatory in 2025

Municipal regulations in Longueuil are precise. Yes, it may seem complicated, but it's there to protect people's safety and maintain neighborhood harmony.

Ignoring regulations can cost you dearly. We're talking fines, forced demolition or complications if you sell your home later. The buyer or building inspector will notice a non-compliant deck, and that will lower the value of your property.

When a permit is required (and when it isn't)

The Ville de Longueuil requires a certificate of authorization (permit) for most terraces and patios. Here are the situations in which you absolutely must obtain one:

If your deck is raised more than 0.6 meters above the ground, a permit is required. This is the basic rule and applies everywhere in Longueuil, regardless of your sector.

If your construction encroaches on the setbacks - that is, if it's too close to your property line, the street or your neighbor's - you also need a permit. Setbacks vary according to residential zone, but in general, you'll need to respect a minimum of 1 to 2 metres.

For a ground-level patio less than 0.6 metres high that respects the setbacks, you generally don't need a permit. But be careful: even without a permit, your patio must still respect drainage regulations and not interfere with your neighbor's property.

If in doubt, call the Longueuil urban planning department or request a free audit with Cartago Construction. We know the regulations by heart and can tell you in 5 minutes whether your project requires a permit.

Guardrails, loads and RBQ standards to be respected

If your deck exceeds 0.9 m in height, you must install a guardrail that complies with the Quebec Construction Code. This is a non-negotiable safety issue.

The guardrail must have a minimum height of 900 millimeters (approx. 36 inches) measured from the surface of the deck. The bars must be spaced at a maximum of 100 millimeters (4 inches) apart to prevent a child from falling through.

The structure of your deck must also support a live load of at least 40 pounds per square foot. This is what the building code requires for residential outdoor spaces. This means your deck must be able to support the weight of several people, furniture and even a BBQ without flexing or buckling.

For RBQ-certified contractors like Cartago Construction, these standards are part of our daily work. We automatically apply them to our plans and installations.

If you hire a contractor, always check his RBQ license. An unlicensed contractor is not allowed to build a deck higher than 0.6 meters in Quebec. You risk insurance and compliance problems.

Online permit application, Ville de Longueuil

The good news is that Longueuil has modernized its permit application process for 2025. You can now submit your application online via the city's portal.

You'll need to provide a plan of your deck or patio with dimensions, location on your lot, height and materials. If it's a raised deck, you'll also need to include a foundation plan showing piles or footings.

Processing time is generally 2 to 4 weeks, depending on the time of year. In April-May, when everyone wants to get started on their outdoor work, it can take a little longer.

Permit fees vary according to the value of the work, but allow between 100 and 300 $ for a standard residential deck project.

Need help navigating the process? At Cartago Construction, we'll take care of the permit application for you. We know exactly what the City is asking for, and we avoid the back-and-forth that delays your project.

Choosing the right materials for a sustainable deck in Quebec

The choice of materials is where many people go wrong. They just look at the initial price without thinking about durability or long-term maintenance.

In Quebec, we don't have the luxury of using just any materials. Our extreme climate - from -30°C in winter to +35°C in summer - puts all materials to the test. UV rays, humidity, freeze-thaw and snow all accelerate degradation.

The right material for your deck is the one that will last in our climate while respecting your budget and aesthetic vision.

Treated wood: economical but demanding

Treated wood is the classic and most economical choice. We're talking about 25 to 50 $ per square foot installed for a quality treated wood deck.

Pressure-treated wood is resistant to decay and insects thanks to the chemical treatment it receives. It's a natural material with a warm, beautiful appearance that's easy to work with.

Treated wood, on the other hand, requires maintenance. You need to stain or seal it every 2-3 years to protect the surface and maintain its appearance. Without maintenance, wood turns gray, cracks appear and the structure loses its strength.

The average lifespan of a well-maintained treated wood deck in Longueuil is 10 to 15 years. If you forget maintenance, you'll be replacing boards long before that.

Treated wood is also prone to warping and splintering, especially after a few years' exposure. If you have children playing barefoot on the deck, this is something to consider.

Composite: the low-maintenance solution

Composite is a mixture of recycled wood fibers and plastic. It has become extremely popular in Quebec in recent years. Composite adoption is estimated to have increased by 10 to 15 % per year since 2020.

The big advantage is minimal maintenance. No staining, no sealing. Just hose it down once or twice a summer, and that's it. Composite also resists freeze-thaw very well, and won't crack, warp or splinter.

In terms of aesthetics, modern composite products imitate natural wood very well. You can choose from a wide range of colors and textures, from ash gray to dark brown.

The cost is higher: count between 45 and 95 $ per square foot installed, depending on brand and quality. But over 20-25 years (the typical lifespan of composite), you save on maintenance and replacements.

One thing to watch out for: composite can become hot under the sun in midsummer. If your terrace is in full afternoon sun, opt for a lighter color that absorbs less heat.

At Cartago Construction, we work with recognized brands such as Trex, TimberTech and Fiberon. These products come with 25 to 50-year warranties against discoloration and structural defects.

Concrete and fiberglass for patios

For a ground-level patio, concrete remains a solid, durable option. A well-built concrete patio in Longueuil can last 50 years or more, if the foundations are right and the drainage is good.

Concrete can be finished in a variety of ways: brushed for a non-slip texture, stamped to imitate stone or cobblestone, or tinted to add color. It's versatile and relatively economical.

On the other hand, concrete is susceptible to cracking if the ground moves. That's why we always insist on a quality compacted gravel base and expansion joints in the right places.

Fiberglass decking is a more recent technology. A fiberglass membrane is poured directly onto the structure, creating a waterproof, slip-resistant and highly durable surface. It's often used for second-floor balconies or roof terraces, but it also works on the ground.

The cost of fiberglass is high (around 60 to 100 $ per square foot), but it's a maintenance-free solution that stands up perfectly to the Quebec climate.

Key steps for building a deck or patio without mistakes

Building a deck or patio is a multi-stage project. If you don't get it right, mistakes will pile up and you'll end up with a disappointing result.

Here's how Cartago Construction ensures long-lasting, compliant work.

Planning, design and implementation

It all starts with a clear plan. We discuss your needs with you: how many people will use the space? Do you want a dining area, garden furniture, a spa? What orientation do you prefer?

Orientation is important. A south-facing terrace gets plenty of sun all day long, which is pleasant in spring and autumn, but can be too hot in July. A north-facing terrace is shadier and cooler in summer.

We also check the setbacks with your certificate of location. It tells us exactly where your property limits are, and whether your project complies with city regulations.

The next step is to lay out the site. We mark the exact location with stakes and rope, so that you can visualize the size and final position of the deck.

At this stage, we also identify underground services (gas, electricity, water) with Info-Excavation. This is mandatory before any excavation in Quebec.

Foundations, anchoring and structure

Once the plan has been approved and the permit obtained, we start with the foundations. For a raised terrace, screw piles are installed to the required depth (minimum 1.2 metres).

Each pile is positioned according to the structural plan. We check the plumbness and make sure all the piles are level with a laser level. This is critical for a straight, stable structure.

Next, we build the framework: beams, joists and bracing. Approved metal screws and fasteners are used, never just nails. The structure must be solid, rigid and able to bear loads.

A crucial point: never attach a deck directly to the house without independent anchoring. If the deck moves due to freeze-thaw and is screwed directly into the house siding, it will tear off the siding or cause water infiltration.

We always prefer to build a self-supporting structure with an expansion space between the deck and the house. It's safer and protects your building.

Surfacing and finishing

Laying the cladding is the last visible step, but that doesn't mean it's any less important. Each board must be laid according to the manufacturer's recommendations, with the correct spacing to allow for expansion and contraction.

For treated wood, we generally leave a space of 3 to 5 millimeters between each plank. For composite, the spacing varies according to brand and installation temperature (composite expands more than wood).

We also install expansion joints at strategic points if the terrace is very large. This prevents long-term cracking and warping.

Finishes include railings (if required), steps, fascias to hide the structure, and possibly integrated lighting. We make sure everything is safe, aesthetically pleasing and up to code.

One last important detail: never install composite or wood when the temperature is below 5°C. At this temperature, the materials are too rigid and can crack or warp. Spring and summer are the best seasons to build a terrace in Longueuil.

How much will a terrace or patio cost in Longueuil in 2025-2026?

The question of budget comes up in all our first meetings. You want to know what you're getting into.

The cost of a terrace or patio varies enormously according to size, materials, complexity of the terrain and finishing touches. But we can give you realistic ranges based on our recent experience in Longueuil.

Sample budgets by surface area and material

For a standard 12' x 12' (144 sq. ft.) treated-wood deck, including screw piles, structure and installation, count between 5,000 and 8,000 $. This is the basic budget for a simple deck, without elaborate railings or high-end finishes.

The same composite deck will cost you between 8,000 and 12,000 $. The price difference comes from the material itself, which costs almost twice as much as treated wood.

If you add an aluminum or glass railing, a staircase with several steps and integrated lighting, add another 3,000 to 5,000 $ to the total.

For a 200-square-foot paver patio with excavation, gravel base and professional installation, expect to pay between 4,000 and 7,000 $. A poured concrete patio of the same size typically costs between 3,500 and 6,000 $.

Larger terraces (300 square feet or more) with two levels, built-in benches and glass railings can easily fetch 20,000 to 30,000 $. It's an investment, but it really adds value to your property.

These prices include labor, materials and compliance with standards. They do not include the municipal permit, which you must pay directly to the Ville de Longueuil.

Want a precise figure for your project? Get a free, no-surprise estimate with Cartago Construction. We come to Longueuil and the South Shore to evaluate your property and offer you a detailed price.

Common myths about terraces in Quebec (and the reality)

We often hear the same misconceptions about terraces. Here's the truth behind three popular myths.

«No need for a permit for a small terrace»

Not true as soon as your deck exceeds 0.6 meters in height. Whatever the size, if it's raised, you need a certificate of authorization in Longueuil.

Some owners think they can build first and ask for forgiveness later. Not a good idea. The city can force you to demolish a non-conforming terrace, and you'll have no recourse.

Even for a ground patio, always check setbacks and drainage regulations. It's better to ask beforehand than to deal with a problem afterwards.

«Treated wood is maintenance-free».»

Another false belief. Treated wood resists decay, yes, but it still needs maintenance to keep its appearance and strength.

Without stain or sealant, the wood will turn gray, split and absorb moisture. After 5-6 years without maintenance, you'll see warped boards and major cracks.

Plan on an annual budget of around 200 to 400 $ for the maintenance of an average-sized deck. This includes washing, light sanding if necessary and the application of a quality sealer.

«We can fix it right at home».»

It's a mistake we see all too often. Fastening a deck directly to the house siding with lag bolts sounds logical, but it's risky.

If the deck moves due to freeze-thaw (and it will if the foundations are poorly done), it will pull on the cladding and create gaps. Water will seep behind the cladding, and then you've got a problem of mold and rot in the structure of your home.

The best method is to build a self-supporting structure with its own foundation. Leave a small gap between the deck and the house, and install metal flashing if necessary to protect the joint.

Why entrust your terrace to Cartago Construction

Building a deck or patio in Longueuil is a project that deserves to be done right the first time. Mistakes cost money and can take years to show up.

At Cartago Construction, we bring over 10 years of residential construction experience to Quebec. We know the challenges of Longueuil's climate, RBQ requirements and municipal bylaws by heart.

RBQ expertise and local knowledge

We're RBQ-certified and liability-insured. That means your project is protected and our work complies with all applicable standards.

We also know the particularities of the territory. Longueuil's clay soils, the flood zones near the river, the specific regulations for certain sectors such as Vieux-Longueuil or Greenfield Park: we've got it all under control.

When we assess your property, we identify potential challenges right away. We tell you honestly what's going to work and what might cause problems down the road.

We also work with trusted subcontractors for screw piles, excavation and specialized finishes. You have a complete team working together to deliver a flawless project.

Turnkey, sustainable and aesthetic approach

Our service is turnkey. This means we take care of everything: design, permit application, purchase of materials, construction and finishing.

You have a single point of contact from start to finish. No need to coordinate multiple contractors or chase suppliers. We manage everything.

We also focus on durability. We use quality materials, install standard foundations and build structures that will last 20, 30 or more years.

And because a terrace is also an aesthetic element, we take care of the details. The cuts are clean, the finishes are meticulous, and the end result reflects your vision.

Ready to plan your deck or patio with a certified contractor in Longueuil? Contact Cartago Construction for a free consultation. We'll help you bring your project to life with professionalism and transparency.

📞 438-932-4326 | ✉️ [email protected] 📍 2580 Rue Cartier, Longueuil, QC

FAQ - Terrace and patio in Longueuil

What's the difference between a terrace and a patio? 

A terrace is elevated and built on a deep foundation, usually at the height of the house door. A patio is at ground level, built on a base of gravel, concrete or interlocking paving stones. In Longueuil, terraces higher than 0.6 meters require a permit, while ground-level patios are often exempt.

Is composite really worth the cost in Quebec? 

Yes, especially if you want to avoid annual maintenance. Composite costs almost twice as much as treated wood up front, but lasts 20 to 25 years without staining or sealing. In the long term, you save on maintenance and board replacement. What's more, it's highly resistant to freeze-thaw.

What depth for piles in Longueuil? 

Screw piles must be at least 1.2 metres deep to pass below the frost line. In some parts of the Montérégie region, we even recommend 1.5 meters to be on the safe side. This is the only way to guarantee that your terrace won't move with the freeze-thaw cycles.

How long does the work last? 

For a medium-sized deck (12×16 feet), allow between 5 and 10 working days, depending on complexity and weather conditions. Pile installation takes 1 day, structure 2-3 days, and siding and finishing another 2-3 days. We can work faster on simple projects or take a little longer for terraces with several levels.

Can you build a terrace in winter? 

Technically yes for the structure, but not for the cladding. Treated wood and composites should not be installed below 5°C, otherwise they may split or warp. Piles and framing can be installed in winter, but boards can only be laid in spring.

What are the risks without a licence? 

If you build without a permit when one is required, the Ville de Longueuil may send you a notice of non-compliance. You'll have to pay a fine and obtain a retroactive permit. In serious cases, the City may require demolition of the structure. What's more, a non-compliant deck can complicate the sale of your home.

Does a terrace increase the value of your home? 

Yes, a beautiful, well-built terrace can increase the resale value of your property by 5,000 to 15,000 $, depending on size and quality. This is one of the best returns on investment for exterior renovations. Buyers appreciate a functional and aesthetically pleasing outdoor space, especially in a market like Longueuil where lots are in high demand.

Building a terrace or patio in Longueuil is a project that really improves your quality of life. A beautiful outdoor space for summer BBQs, evenings with friends or simply relaxing with a morning coffee, it's worth the investment.

But for your project to last and meet standards, you need to do things right. Solid foundations, materials adapted to the Quebec climate, proper permits and professional construction: that's what makes the difference between a deck that lasts 20 years and one that causes problems after 3.

At Cartago Construction, we build decks and patios that stand the test of time and make our customers proud. If you're ready to get started on your project for the summer of 2026, now is a good time to plan.

Call us at 438-932-4326 or e-mail us at [email protected] for a free quote. We go everywhere in Longueuil, Brossard, Saint-Hubert and on the South Shore.