The local context plays a decisive role. In Longueuil, 60 % of homes date from before 1980, and the region's humid climate creates particular challenges. These factors make the basement a space with great potential, but one that requires an expert approach.

At Cartago Construction, our two years of experience in Longueuil have taught us that every basement tells a different story. Here's what really defines the trends of 2025.

Underground market and economic potential in 2025

Growth and investment

The Association provinciale des constructeurs d'habitations du Québec (APCHQ) forecasts a 9 % increase in basement renovation starts in 2025. This growth reflects sustained demand to optimize existing living space.

Average investments range from $70 to $100 per square foot. For a standard 800-square-foot basement in Longueuil, you'll pay between $56,000 and $80,000, depending on the complexity of the project.

Return on investment

The figures speak for themselves: a well-renovated basement generates a return on investment of 70 to 85 % at the time of resale. Beyond this added value, homeowners save 10 to 15 % on their energy bills thanks to better insulation and more efficient systems.

On the South Shore, where space is at a premium, converting your basement is often the most economical way to expand your living space.

Six trends that will redefine basements in 2025

1. Multifunctional spaces: the new standard

Gone are the days of single-purpose basements. Longueuil homeowners create modular spaces that adapt to changing family needs.

Scalable home offices with removable partitions that turn into playrooms in the evening. Family gyms with integrated equipment storage. Home theaters which become reception rooms for events.

This modularity is perfectly suited to the realities of telecommuting and home schooling, which are still very much in evidence in the region.

2. Biophilic design and natural light

The dark basement is a thing of the past. The installation of egress windows is becoming standard, not only for safety, but to transform the ambiance of the space.

Integrating plants adapted to low-light environments creates a soothing atmosphere. Pothos, sansevieria and philodendrons thrive in these conditions while purifying the air.

Natural textures - reclaimed wood, accent stone, plant fibers - warm up the space and counterbalance the sometimes cold appearance of the basements.

3. Smart homes and energy efficiency

Home automation transforms basements into advanced technological spaces. Intelligent thermostats enable energy savings of 10 %, particularly important in basements where thermal regulation is often a problem.

Automated lighting that adapts to activities: subdued light for the cinema, bright light for the office, colorful ambience for parties. Integrated audio systems in suspended ceilings avoid clutter while delivering optimum sound quality.

4. Sustainable materials and thermal comfort

Homeowners now prefer environmentally-friendly materials. Recycled wood for wall coverings, low-VOC paints for air quality, ecological insulation made from recycled fibers.

High-performance insulation becomes a priority. In the pre-1980 homes of LongueuilWe systematically recommend upgrading foundation insulation to eliminate thermal bridges and control humidity.

5. Wellness and relaxation areas

The basement becomes a personal sanctuary. Compact saunas adapted to small dimensions, yoga rooms with mirrors and built-in storage, meditation areas with mood lighting.

Acoustic comfort is of particular importance. Decorative acoustic panels, sound-absorbing partitions and suspended ceilings with absorbent materials create peaceful environments even in busy homes.

6. Legal apartments and rental income

The creation of accessory dwelling units (ADUs) in the basement is a response to the housing crisis. These self-contained, RBQ-compliant apartments generate substantial rental income.

In Longueuil, a well-appointed basement apartment rents for between $1,200 and $1,600 a month, depending on floor area and finishes. This trend requires careful planning to comply with municipal regulations.

Longueuil's specific challenges and expert solutions

Humidity and mold: top priority

The South Shore's humid climate makes humidity management critical. French drainage around the foundations, waterproofing membranes modern and heat recovery systems (HRV) form the trifecta against humidity.

Our recent projects show that a preventive approach costs 30 % less than a corrective repair after water damage.

Older homes: time for an upgrade

Homes built before 1980 are often in need of electrical and plumbing upgrades. Insufficient 100-amp electrical panel, original copper piping, outdated insulation: these elements require attention before any cosmetic renovation.

Cartago Construction systematically assesses these technical aspects during the initial estimate, to avoid surprises during the project.

Available subsidies

Several financial assistance programs apply to basement renovations:

LogisVert for energy-efficiency upgrades (up to 5,000 $). Rénoclimat for energy audits and eligible work. GST/QST rebate for certain new-build projects in basements.

These programs can significantly reduce project costs, particularly for energy upgrades.

Myths and realities: what you really need to know

Myth 1: The open concept always works best

Reality: 2025 enhances both intimate and functional zones. A completely open basement lacks definition and acoustic comfort. Semi-open spaces with visual separations create more ambience.

Myth 2: Do-it-yourself saves big bucks

Reality: Basement mistakes are expensive in the long run. Poorly treated moisture problems, inadequate insulation, non-compliant electricity can lead to additional costs of up to 30 % of the initial budget.

Myth 3: Basements don't need natural light

Reality: The addition of egress windows increases occupant well-being and property value by 15 %. These windows transform the atmosphere and enable the creation of legal rooms.

Myth 4: It's only aesthetic

Reality: Energy efficiency and waterproofing are top priorities. A beautiful basement that develops moisture problems quickly loses its value and becomes a money pit.

Local market news and trends 2025

Cost trends

Material prices rose by 0.9 % in 2025, a moderate increase that keeps renovation projects affordable. This relative stability encourages homeowners to proceed with their projects.

Growing demand for basement apartments

The housing crisis is stimulating demand for accessory units. In Longueuil, approval times for basement apartment permits have been reduced, facilitating these projects.

Impact of municipal work

Longueuil's road rehabilitation program can affect access to worksites during the summer. Planning material deliveries and crew access becomes an important logistical consideration.

Longueuil's specialized contractors forecasts growth of 12 % this year, reflecting sustained demand for these complex projects.

A practical guide to a successful basement project

Pre-evaluation: the basis for success

Before any aesthetic planning, assess the structural and environmental condition of your basement. Humidity testfoundation inspection and assessment of existing ventilation systems guide technical decisions.

This assessment often reveals potential savings, or problems that would have been costly if discovered during renovation.

Technical priorities

HRV insulation and ventilation come first. A poorly insulated basement will remain uncomfortable even with the finest finishes. A modern HRV system eliminates excessive humidity and ensures optimum air quality.

Electricity and plumbing must be planned from the outset. Adding sockets, lighting or a bathroom after finishing costs three times as much.

Realistic budget

Allow an extra 10 to 15 % for contingencies. Basements often hold surprises: unmapped piping, drainage problems, electrical upgrades required.

This room for manoeuvre avoids site stoppages and compromises on quality.

Intelligent integration

Plan home automation right from the design stage. Wiring for high-speed Internetintegrated USB sockets and pre-wiring for audio systems create a modern, functional basement.

Biophilic elements - LED lighting reproducing natural light, accent walls in natural materials, space for vegetation - transform the ambiance of the basement.

Frequently asked questions

What colors and materials to choose for 2025?

Earthy tones dominate: terracotta, deep olive and nuanced beiges replace cool whites. Reclaimed wood, accent stone and textured ceramics bring character and warmth.

When it comes to materials, opt for moisture-resistant options: luxury vinyl waterproof, anti-mould paints, synthetic insulation not degradable by humidity.

Is insulation mandatory before renovation?

Absolutely. Quebec standards require a minimum of R-12 insulation for foundation walls. Beyond compliance, high-performance insulation eliminates condensation, reduces heating costs and creates a comfortable year-round space.

Average budget and cost factors

Count 70 to 100 $/ft² depending on complexity. Factors influencing costs :

• Initial condition of basement (humidity, electricity, plumbing)
• Desired finish level
• Adding a bathroom or kitchenette
• Planning complexity
• Quality of materials

Compatible smart technologies

Philips Hue lighting or equivalent for modular environments. Nest thermostats for multiple zones. Sonos audio systems integrated. Intelligent sockets for remote control.

The important thing is to plan the appropriate wiring from the outset, to avoid the need for makeshift solutions.

Permits and regulations in Longueuil

Permits required for all work involving structural, electrical or plumbing modifications. Zoning rules specific for legal apartments: minimum height 7'6″, two emergency exits, escape window.

Cartago Construction manages all administrative procedures to ensure that your project is fully compliant.

Transform your basement with Longueuil experts

Investing in a basement renovation in 2025 combines family comfort, property value and energy savings. Today's trends emphasize functionality, sustainability and well-being, creating spaces that truly enrich your daily life.

At Cartago Construction, we master the unique challenges of Longueuil's basements. Our ten years of experience in Quebec residential construction enable us to anticipate problems and deliver lasting solutions.

Contact us at 438-932-4326 for a free evaluation of your basement. We analyze your specific situation, respect your budget and create a space that follows the best trends of 2025.

Your basement can become the jewel of your home. Make it a reality with experts who understand the challenges and opportunities of the South Shore.