Roof Structure and Components

The strength and durability of a roof don’t rely solely on the outer covering. Everything starts with a crucial foundation: the roof structure, with the roof frame as its central pillar. Whether you’re planning new construction, renovation, or inspection, it’s essential to understand the components that make up this invisible framework.

Learn what a roof frame is, how a roof structure works, and which roofing parts ensure strength, insulation, and ventilation.

What is a roof frame?

The roof frame is the skeleton that supports the entire roof covering of a building. It forms the structural base upon which other roof structure components rest, such as insulation, membrane, and exterior cladding.

Designed to distribute vertical loads (roof weight, snow, etc.) and horizontal forces (wind), the roof frame ensures the stability and safety of the entire building.

The structural role of the roof frame

Without a solid and well-designed frame, the roof cannot fulfill its essential functions, including:

• Supporting the weight of roofing materials, insulation, and additional equipment (e.g., solar panels, skylights)
• Resisting climatic loads typical in Quebec: snow accumulation, freezing rain, strong winds
• Maintaining the structural integrity of the building by evenly distributing mechanical stress
• Allowing proper ventilation and insulation by defining the airflow volumes under the roof

Different types of roof frames

Traditional frame

Built on-site using solid wood, the traditional frame is known for its strength and durability. It allows for more architectural freedom, especially for converted attics. However, it requires expert craftsmanship and is often more expensive.

Engineered truss roof frame

Made from prefabricated trusses—usually engineered wood—this is the most common frame in modern residential construction. It is:

• Cost-effective
• Quick to install
• Optimized for standardized loads

However, it offers less flexibility for interior layouts, as the space between trusses is usually not usable.

Flat roof frame

Flat roofs, common in commercial or modern buildings, use low-slope frames made of wood, steel, or concrete joists. These structures must be designed to prevent water accumulation—a critical concern in Quebec.

Key roof structure components

A roof is more than its frame or load-bearing structure. To be functional, durable, and compliant with Quebec’s building codes, several roofing parts must be installed in successive layers.

Roof covering

The roof covering is the first barrier against weather. It protects the roof structure from water, snow, wind, and UV rays. Common types include:

Elastomeric or TPO membranes

Used mainly for flat or low-slope roofs, these membranes are highly resistant to leaks but must be professionally installed.

Asphalt shingles

Popular in residential buildings for their great price-to-performance ratio. Easy to install and replace, they’re a practical and economical choice.

Metal roofing

Offers exceptional durability (40+ years) and withstands extreme weather. Its modern look is ideal for steep-slope roofs.

Insulation and ventilation

Roof insulation helps retain heat in winter and keep cool air in during summer. It’s often paired with efficient ventilation, which is crucial to prevent condensation, excess moisture, and mold.

Key principles:

• Air must circulate freely between the insulation and the interior roof surface
• Soffits, roof vents, and ridge vents ensure natural air flow

Vapor barrier, underlayment, and gutters

Vapor barrier

Installed inside the roof to stop moisture from heated rooms from reaching the insulation.

Underlayment

Positioned between the frame and the covering, it acts as extra protection in case of leaks or ice dams.

Gutters

Essential for redirecting rainwater away from foundations, preventing infiltration and soil erosion around the building.

Safety components

Some roof structure components are less visible but vital for safety:

• Permanent anchor lines: Let roofers work safely during maintenance
• Baffles: Direct airflow in the attic
• Ice guards: Prevent ice dams at the roof edge

How to choose the right roof structure

Roof structure design should never be left to chance. Many factors influence the choice of frame and roofing parts. Whether you’re building or renovating, these criteria determine the performance, safety, and compliance of your roof.

Type of building: residential, commercial, or industrial

• Residential: Light wood frames like trusses are preferred for single-family homes or small apartment buildings.
• Commercial: Flat roofs with metal or concrete frames are common, simplifying mechanical equipment installation.
• Industrial: Require reinforced structures that span wide areas without intermediate columns—usually steel.

Snow load in Quebec

Snow load is a critical consideration in structural calculations. Winter snow can weigh hundreds of kilograms per square meter.

You need to assess:

• The climate zone (some areas get more snow than others)
• Roof pitch (the lower the slope, the more snow it holds)
• Covering material (some allow snow to slide off more easily)

An undersized frame can lead to sagging or even collapse.

Roof pitch and material choice

Roof pitch affects both the building’s look and what kind of frame and roofing parts are suitable.

• Steep slopes: Ideal for asphalt shingles or metal roofing, with good water and snow runoff.
• Low slopes or flat roofs: Require waterproof membranes (elastomeric or TPO) and reinforced structures for standing water.

Each material has specific support, spacing, and reinforcement needs.

Building code compliance in Quebec

Quebec’s Construction Code sets minimum requirements for roof design, including:

• Climate loads (snow, wind)
• Required types of anchors and connectors
• Resistance to fire, moisture, and corrosion

Working with a professional ensures compliance with these standards and suitability for the intended use.

Roof structure maintenance and inspection

The roof structure and frame are under constant stress. Regular inspections help preserve the building’s integrity and avoid costly repairs.

Why inspect your roof frame and components?

Regular checks help to:

• Prevent structural damage before it becomes critical
• Detect leaks or moisture issues affecting insulation or promoting mold
• Check fasteners, anchors, and load-bearing elements
• Confirm roof compliance after extreme weather (heavy snow, windstorms, freezing rain)

Warning signs to look for

Certain signs require immediate attention:

Inside the building:

• Unusual cracks on walls or ceilings
• Doors or windows jamming (structural shift)
• Moisture stains or mold in the attic

Outside or in the attic:

• Visible roof sagging
• Curled or missing shingles
• Cracked or warped beams
• Persistent moisture smells

Even minor anomalies may indicate weakening or misalignment of the structure.

Recommended inspection frequence

Best practices in Quebec:

• Visual inspection once a year: Spring or fall, to catch early signs of deterioration
• Thorough inspection every 3 to 5 years, ideally by a roofer or structural engineer
• One-off inspections after major weather events (e.g., extreme snow, storms)

Preventive maintenance extends the roof’s lifespan and reduces costly repair risks.

When should a roof frame or structure be replaced?

Replacing a roof frame or the entire structure is a major but sometimes necessary intervention. Several scenarios may require partial or full reconstruction to ensure building safety and code compliance.

Renovation or structural transformation

If you’re adding a floor, changing the roof slope, or modifying the building structure, the current frame may no longer be suitable and must be reinforced or rebuilt.

Expansion or new usage

Turning an attic into living space or expanding the roof may require:

• Slope modification
• Support point adjustments
• Adaptation to new loads

Structural defects or damage

Total reconstruction is required when:

• The frame is poorly designed or outdated
• Major deformation or sagging is present
• Mold or rot has spread through the wood
• Damage from insects or chronic water infiltration is found

Approximate costs in Quebec

Replacement costs vary based on surface area, materials, project complexity, accessibility, etc.

Estimated range:

• Partial frame replacement: $2,000 to $8,000
• Full roof structure replacement: $20,000 to $50,000+, depending on building size and complexity

These prices generally include demolition, reconstruction, materials, and labor, but may vary by region.

Hire an expert to assess your roof structure

Before starting any work on your roof frame, consult with experts. At Les Couvreurs Duro-Toit, we bring proven expertise to evaluate your roof’s condition, confirm project feasibility, and ensure compliance with the Quebec Building Code.

Whether you need an inspection, renovation, or complete replacement, our team offers reliable, transparent support—avoiding surprises and ensuring long-term roof durability. Contact us today for a free estimate.