Is your bungalow starting to run out of space, but the idea of moving is giving you headaches? You look at your flat roof and wonder, «What if we added a floor?»

It's a question we often hear at Cartago Construction. And the short answer is: yes, it's often possible. But there are some important conditions to meet.

With home prices in Longueuil climbing 9.1% last year, more and more homeowners are choosing to expand upwards rather than look for a new property. We're talking about families who need an extra bedroom, parents who want to create a home for their seniors, or simply homeowners who want to maximize their investment.

In this guide, I'll explain exactly what you need to know before adding a floor to your home. The Longueuil bylaws, the actual costs, the steps to follow, and most importantly, the mistakes that can cost you.

Why consider a floor addition in Longueuil?

Adding a floor isn't just a question of space. It's a smart way to meet changing needs without turning everything upside down.

The homeowners we meet tell us about the same situations: children grow up and want their own room, aging parents need a home that's accessible but close to the family, or permanent telecommuters need a real, enclosed office.

Benefits for multi-generational families

The big-generation home concept is gaining in popularity in Longueuil, particularly in areas like Saint-Hubert and Vieux-Longueuil.

Adding a second floor allows you to create an independent home for your parents or adult children. A full floor can include two bedrooms, a bathroom, a small living room, and even a kitchenette. Everyone keeps their privacy, but the family stays close.

There are even subsidy programs for this type of project. The AccèsLogis Québec program offers financing for projects that create accessible or intergenerational housing. It's worth checking your eligibility before you get started.

We did a project last year for a family in Greenfield Park. They added an 800-square-foot floor for the grandparents. The result? The family stays together, the grandparents have their autonomy, and the value of the house has increased significantly.

Find out how other Longueuil families have transformed their bungalows. See our local case studies.

Financial impact and valuation

Let's talk money. Because this is a major investment.

A floor addition in Longueuil typically costs between 225$ and 300$ per square foot, all inclusive. For a full floor of 800 to 1,000 square feet, you're looking at a budget of 180,000$ to 300,000$.

That's a lot. But let's compare it with the alternative.

Selling your current home and buying a larger one in Longueuil would easily cost you an additional 100,000$ to 150,000$, not to mention transaction fees (commission, notary, transfer taxes) that can run as high as 30,000$ to 40,000$.

What about value? A well-designed and executed second-storey addition can increase the value of your property by 7% to 12%, according to APCHQ data. On a house valued at 450,000$, this represents between 31,500$ and 54,000$.

The return on investment is rarely immediate and total, but it's real. And you get exactly the space you need, in the neighborhood you already love.

The Longueuil market also favors densification. With new municipal policies encouraging the addition of housing on existing lots, a house with an extra unit becomes more attractive to potential buyers.

Regulations and permits required in Longueuil

This is the technical part. And it's important, because a mistake here can bring your project to a screeching halt.

The City of Longueuil has specific regulations on what you can and can't do. Bylaw CO-2024-1286 governs storey additions in residential zones.

When a permit is required

The simple answer: always.

Every floor addition requires a building permit in Longueuil, without exception. Even if you're only adding 10 square meters, you have to go through the whole process.

The permit costs between 1,500$ and 4,000$, depending on the complexity of your project. Approval times vary from 30 to 60 working days, sometimes longer if adjustments are required.

To obtain your permit, you will need:

Complete architectural plans signed by an architect or technologist. Structural plans signed by an engineer (mandatory for a storey addition). Up-to-date certificate of location showing the exact dimensions of your lot and house. Certificate of compliance for septic system if you are off-grid. Current photos of your property.

We take care of preparing and filing all these documents for our customers. This eliminates the frustrating back-and-forth with the City.

Zoning and urban planning audits

Does your lot really allow for a storey addition? Here's what the city will check.

• Maximum height: In most residential areas of Longueuil, the maximum height allowed is 10 meters (about 33 feet). If your current bungalow is 4 meters high, you have 6 meters available for your new floor. That usually leaves enough space for a standard floor with 8 to 9 feet of ceiling.
• Ground level: Adding a storey doesn't change your right-of-way (since you're building upwards, not sideways), but your property must still respect the existing limits. If you're already at the maximum allowable right-of-way, this could complicate matters.
• Side and rear margins: Even for a vertical addition, the City verifies that your home respects the 2 to 3-metre setbacks from lot lines.

Regulations vary slightly by sector. Vieux-Longueuil, with its heritage character, may have additional requirements for exterior appearance. Saint-Hubert and Greenfield Park generally have more flexible rules for residential bungalows.

A recent certificate of location is essential. If yours is more than 10 years old, you'll need to order a new one (cost: 1,000$ to 1,500$).

Need to know if your property allows an addition? We'll check your zoning free of charge before we start.

Energy standards and RBQ compliance

The Quebec Construction Code now imposes strict energy standards for all new floors.

The aim is to reduce energy consumption by 40% compared with previous standards. In practical terms, this means:

Reinforced insulation in walls and roof (minimum R-40 value for roof, R-24 for walls). Energy-efficient windows with triple glazing in many cases. Airtightness system tested by infiltrometry. Mechanical ventilation with heat exchanger to maintain air quality.

These requirements increase construction costs by about 8% to 12%, but they considerably reduce your heating bills. In Longueuil's climate, good insulation really does make the difference between a Hydro-Québec bill of 150$ per month and one of 90$.

Non-compliance with RBQ standards can result in fines of 5,000$ to 10,000$, refusal of the final certificate of occupancy, and major problems when reselling your home.

Key steps for adding a second floor to your home

Now that we've covered the regulations, let's take a look at the entire process, step by step.

A storey addition project generally takes between 6 and 10 months from start to finish. This is longer than a horizontal extension because the structural complexity is greater.

Step 1. Structural assessment

Before you even think about design, you need to know whether your home can support an extra floor.

A structural engineer must inspect your property and answer three critical questions:

Are your foundations solid enough? Bungalows built from the 1960s to the 1980s often have foundations designed solely for their current weight. Adding a full floor can represent a surcharge of 40,000 to 60,000 pounds.

Longueuil's clay soils complicate matters. The marine clay found in our region contracts and expands with changes in humidity. If your foundations aren't deep enough or wide enough, you'll need to reinforce them before adding a storey.

Foundation reinforcement costs between 15,000$ and 40,000$, depending on the extent of the work required. This can include adding piles, widening existing footings, or even completely replacing damaged sections.

Are your load-bearing walls adequate? The walls that currently support your roof will have to support a full floor. The engineer checks their structural capacity and determines whether they need to be reinforced.

Can your current framework be used as a floor? In some cases, the existing roof structure can be reinforced and converted into a floor for the new storey. In other cases, this structure needs to be completely rebuilt.

A structural assessment costs between 1,500$ and 3,000$. It's an essential investment that will help you avoid costly surprises in the middle of a job.

Step 2. Tender and budget

Once the engineer confirms that your home can support a second floor, a realistic budget can be established.

For a standard floor addition in Longueuil, here are the typical costs in 2025:

Structure and foundations (if reinforcement is required): 30 000$ to 60 000$ Lifting and demolition of the existing roof: 8 000$ to 15 000$ Construction of the new floor (framework, insulation, cladding): 120 000$ to 180 000$ for 800-1000 ft² Electricity, plumbing, heating: 20 000$ to 35 000$ Interior finishing (gypsum, paint, floors, cabinets): 40 000$ to 70 000$ Interior staircase: 8 000$ to 15 000$ Unforeseen events and contingencies (10-15%): 15 000$ to 30 000$

Typical total for a floor of 800 to 1,000 sq. ft: 180 000$ to 300 000$

These figures include everything: materials, labor, permits and project management. They do not include furnishings or appliances.

Local subsidies are available to reduce these costs. The Rénoclimat program offers up to 5,000$ for energy-efficient renovations. If you're creating intergenerational housing, other Société d'habitation du Québec programs may apply.

Get a detailed, transparent quote for your floor addition project, free of charge.

Step 3. Elevation work

This is the most impressive phase of the project. Your roof disappears, and a new floor appears in just a few weeks.

The typical process:

Weeks 1-2: Installation of a temporary waterproof roof to protect the interior of your home. This is crucial, because the work can extend over several weeks, and your home can't be left open to the elements.

Weeks 3-4: Controlled demolition of the existing roof. The structure is usually retained for reuse as the floor of the new storey.

Weeks 5-8: Building the framework for the new floor. Either traditional timber framing or prefabricated modules can be used, reducing lead times from 15% to 20%.

Weeks 9-10: Installation of new roof, windows and siding. At this stage, your home is once again watertight.

Weeks 11-14: Installation of insulation to 2025 standards, electricity, plumbing and heating system.

Weeks 15-20: Complete interior finishing. Drywall, paint, flooring, kitchen and bathroom cabinets, light fixtures.

During the work, you can generally continue to live on the first floor. There will be noise and dust, but we're taking precautions to minimize the inconvenience: protective barriers, respectful working hours (generally 7 a.m. to 5 p.m. on weekdays), daily site clean-up.

Step 4. Finalization and inspection

The final step is the official validation of your project.

The municipal inspector comes to check that everything complies with approved plans and the Quebec Construction Code. In particular, he checks:

Structural compliance. Insulation and airtightness. Electrical and plumbing systems. Emergency exits (bedroom windows, smoke detectors). Accessibility and safety (stair railings, ceiling height).

If everything is in order, you'll receive your final certificate of occupancy. This document is essential for the future resale of your home.

At Cartago, we offer a full warranty on our work. Structure: 5 years. Systems (electrical, plumbing, heating): 3 years. Finishing: 1 year.

We also follow up three months after completion to make sure everything is working as planned. Because a successful project isn't just a finished project. It's a project where the customer is truly satisfied.

Myths and misconceptions about floor additions

After 10 years in the business, we've heard a lot of myths. Some are funny, others can cost you dearly if you believe them.

Here are the most common, and the real truth behind each.

Myth: «All bungalows can accommodate an upper floor».»

Wrong. And it's important to understand this right from the start.

Approximately 30% to 40% of the bungalows we assess can't support an additional floor without major reinforcement work. And in some cases, reinforcement is so expensive that it's no longer worth it.

Houses built before 1970 are particularly at risk. Construction standards were different, foundations were often shallower, and soils were not always well compacted.

If your bungalow already has significant cracks in the foundation, sticking doors, or uneven floors, these are signs that the current structure is already struggling with its own weight. Adding a floor under these conditions would be dangerous.

That's why a structural assessment by an engineer is the mandatory first step. Not the second, not the third. It's the first.

Myth: «I can do the project myself to save money».»

We understand the appeal. You look at the budget of 200,000$ and think, «If I do some of the work, I'll save 50,000$.»

The reality? DIY elevation projects have a major problem rate of around 40%, according to data from the Régie du bâtiment du Québec.

The most common mistakes:

Erroneous structural calculations that cause settling or cracking. Inadequate insulation that creates condensation and mold. Non-compliant electrical systems that pose a fire hazard. Inadequate waterproofing that lets water in and damages the structure.

And here's the problem: correcting these errors usually costs 30% to 50% more than doing things right the first time.

Not to mention that your home insurance may refuse to cover damage caused by unprofessional work. And the city can force you to demolish the entire building if the work doesn't meet standards.

Some tasks can be done by a do-it-yourself homeowner: painting, laying floating floors, installing simple light fixtures. But structure, insulation, electricity and plumbing? Leave that to RBQ-certified professionals.

Risks of ignoring a permit or engineer

Let's face it: yes, it happens. Owners who decide to build without a permit to «avoid delays and hassle».

Here's what can happen:

Fines: The Ville de Longueuil can impose fines ranging from 5,000$ to 10,000$ for non-compliant work. And these fines can be repeated if you don't rectify the situation quickly.

Demolition order: In serious cases, the city can force you to demolish what you've built. Yes, even if you've already spent 150,000$.

Resale problems: When you sell your home, the notary will require a declaration from the seller. If you've done any work without a permit, you must declare it. The buyer can then:

• Requiring you to obtain permits retroactively (often impossible or very costly)
• Negotiate a substantial price reduction
• Cancel sale completely

Insurance refusal: Your insurer may refuse to cover damage caused by substandard work. If your roof collapses because of a structural error, you pay for it out of your own pocket.

The reality? A license costs between 2,000$ and 4,000$. The engineer costs between 3,000$ and 5,000$. That's 3% to 5% of your total budget. That's not the place to cut.

Differences between vertical and horizontal extension

Many homeowners ask us, «Why not enlarge towards the back rather than upwards?»

Both options have their advantages. Here's how they compare:

• Cost: Horizontal extension typically costs 225$ to 270$ per square foot. The vertical extension costs 225$ to 300$ per square foot. The difference comes mainly from the greater structural requirements for a storey addition.
• KING: Both options offer a similar return on investment (5% to 12% increase in value), but the storey addition sometimes has a slight advantage because it preserves your backyard.
• Field constraints: If your plot is small, or if you've already reached the maximum permitted footprint, a vertical extension is often your only option. Conversely, if your foundations are weak, or if your zone doesn't allow you to exceed 10 meters in height, a horizontal extension makes more sense.
• Construction time: Horizontal extension is generally faster (12 to 16 weeks vs. 20 to 28 weeks for a storey addition).
• Impact during construction: The horizontal extension lets you keep to your normal routine. Floor additions can be more disruptive, especially during the phase when the roof is removed.

There are also different subsidies available. Eco-energy programs sometimes favor one or the other, depending on your specific situation.

FAQ. Frequently asked questions about floor additions

Is it possible to add a storey to any bungalow in Longueuil?

No, unfortunately. Approximately 30% to 40% of bungalows require major foundation reinforcement work before they can support an additional floor. Homes built before 1970, those on unstable clay soils, or those already showing signs of settlement are particularly at risk. A structural evaluation by an engineer (1,500$ to 3,000$) will tell you exactly whether your home is a candidate.

What is the average cost of an extra floor?

For a full floor of 800 to 1,000 square feet in Longueuil, count between 180,000$ and 300,000$, all included. This price covers foundation reinforcement if necessary, structure, insulation to 2025 standards, electricity, plumbing, heating, and complete finishing. Simpler projects without major reinforcement are towards the lower end of this range, while complex projects with full kitchens and two bathrooms are towards the top.

How long does the whole project take?

From initial assessment to handover of keys, allow 6 to 10 months:

• Evaluation and design: 6 to 10 weeks
• Licensing: 6 to 8 weeks
• Construction: 20 to 28 weeks
• Final inspection: 1 to 2 weeks

Timelines vary according to the complexity of your project, the time of year (springtime projects tend to move faster), and how quickly your permit is approved by the city.

Do I need an engineer for a 1960 house?

Yes, absolutely. It's even more important for older homes. Construction standards in the 1960s were very different from those of today. Foundations were often shallower, footings less wide, and the soils beneath the house were not always well compacted. A structural engineer must analyze your property and sign the structural plans. This is a requirement of the Ville de Longueuil for all storey additions, regardless of the age of the house.

Are there any grants for energy-efficient retrofits?

Yes, several programs may apply. Rénoclimat offers up to 5,000$ for renovations that improve your home's energy efficiency. If you're creating accessible intergenerational housing, the AccèsLogis Québec program may offer additional financing. Hydro-Québec also offers rebates for the installation of efficient heating systems. Eligibility criteria change regularly, so always check available programs when planning your project.

How does the new floor affect resale value?

A well-designed and well-built second-storey addition generally increases the value of your property by 7% to 12%, according to APCHQ data. On a 450,000$ house, this represents between 31,500$ and 54,000$. Return on investment depends on several factors: quality of construction, architectural integration with the rest of the house, number of bedrooms and bathrooms added, and market demand in your specific neighborhood. Homes with intergenerational housing are particularly in demand in 2025.

Can I live in my house while the work is being done?

Yes, in most cases. You can continue to live on the first floor while the second floor is being built. There will be noise during working hours (usually 7 a.m. to 5 p.m.), and there will be a 3-5 day period when the house will be open while the old roof is removed and the temporary roof installed. Protective barriers are installed, the site is cleaned daily, and disruption is kept to a minimum. Some families still choose to stay with relatives for a few weeks during the most intensive phase.

What's the difference between an architect and a technologist?

Both can prepare plans for your floor addition, but their training differs. An architect has completed a master's degree in architecture and can manage complex projects with important aesthetic aspects. An architectural technologist has completed a technical DEC and focuses more on technical aspects and code compliance. For a standard floor addition, one technologist is usually sufficient (and less expensive). For a project with complex architectural elements or in a heritage zone, an architect may be preferable.

Do you have other questions specific to your situation? Contact our experts for a personalized consultation.

Why choose Cartago Construction for your project

Let's cut to the chase: adding a second floor to your home is a major project. It requires technical expertise, experience with local regulations, and a reliable team from start to finish.

Here's why hundreds of homeowners in Longueuil and the Montérégie region have trusted us with their projects.

Over 10 years' experience in residential construction in Quebec

Yassine Troudi, our founder, has been working in Quebec residential construction for over 10 years. He knows the specific challenges of our region: shifting clay soils, harsh winters that test insulation, changing municipal regulations.

We've completed storey addition projects in all areas of Longueuil: Vieux-Longueuil, Saint-Hubert, Greenfield Park, and surrounding areas. We know the peculiarities of each zone, and we know exactly how to navigate the approval process.

Complete turnkey approach

You don't have to juggle five different contractors. We coordinate everything:

Structural assessment with our partner engineers. Preparation of plans with our architects and technologists. Submission and follow-up of your permit application. Complete construction with our team and certified subcontractors. Municipal inspections and final acceptance.

One point of contact. One calendar. One person to blame if something goes wrong. That's the real turnkey approach.

RBQ certification and full insurance coverage

Cartago Construction holds a valid RBQ license and comprehensive liability insurance. It's not just a piece of paper: it's your protection.

Our RBQ license guarantees that:

Our work complies with the Quebec Construction Code and all applicable standards. You're covered by the residential building warranty plan. In the event of a problem, you have clear legal recourse. Your investment is protected.

We also keep up to date with all new requirements, including the 2025 energy standards, which target a 40% reduction in consumption.

Total transparency on costs and deadlines

We hate surprises as much as you do.

That's why we provide detailed quotes that show exactly what's involved:

The cost of each phase of the project. Materials included and their quality. Realistic deadlines for each stage. A clearly identified contingency reserve.

And we communicate regularly during construction. You'll receive weekly progress updates, and we're easy to reach if you have any questions.

Concrete examples of completed projects

Last year, a full floor was added to a bungalow in Saint-Hubert. The family needed two additional bedrooms and a bathroom for their three children.

Budget: 195 000$. Duration: 7 months from start to finish.

The result? They now have a 750-square-foot second floor with three bedrooms, a full bathroom, and a large walk-in closet. The finish blends in perfectly with the rest of the house, and the appraiser estimated that the property's value increased by 48,000$.

We also completed a project for a family in Greenfield Park who wanted to create a home for their grandparents. We added a 900-square-foot second floor with a full kitchen, living room, bedroom and accessible bathroom.

Thanks to AccèsLogis subsidies, they received 12,000$ of financing. And today, three generations are living under the same roof, while retaining their privacy.

Schedule your free structural inspection and find out if your home can accommodate an extra floor.

Ready to convert your bungalow?

Now you know exactly what's involved in a floor addition in Longueuil. The possibilities, the constraints, the costs, and the whole process.

But every house is different. Every lot has its own particularities. And every family has specific needs.

The only way to know for sure whether your project is feasible is to have your property appraised by professionals who really know the local challenges.

At Cartago Construction, we offer a free initial consultation. We come to your home, assess the possibilities, and give you a realistic idea of what's feasible and how much it would cost.

No pressure. No hard sell. Just honest advice based on 10 years of experience in Quebec residential construction.

Call Yassine today to discuss your project: 438-932-4326 or write to us at info@cartagoconstruction.ca

Cartago Construction
2580 Rue Cartier, Longueuil, QC
RBQ certified | Fully insured | Floor addition specialists in Montérégie