1hr and 2 hrs Fire Rating Wall Differences Explained

Fire resistance ratings are crucial in the construction and design of buildings, especially concerning safety and code compliance in Calgary. A fire rating wall is a barrier designed to prevent the spread of fire, thereby allowing occupants time to evacuate and limiting property damage. The ratings of these walls, such as 1-hour or 2-hour, represent the duration that a specific wall assembly can withstand exposure to fire while still performing its function.

Understanding the difference between a 1-hour and a 2-hour fire rating is essential for architects, builders, and building owners. The primary distinction lies in the length of time the wall can sustain its structural integrity and resist fire under test conditions. A 1-hour rated wall has been tested to withstand fire for at least one hour, whereas a 2-hour rated wall is expected to endure for a minimum of two hours.

The choice between the two ratings will depend on various factors, including building codes, the type of structure, and its intended use. Building codes in Canada often specify the required fire resistance rating based on the building’s occupancy, location, and size. Safety is the primary concern, ensuring that the occupants have enough time to evacuate in the event of a fire and that the spread of fire and smoke is adequately contained.

Fundamentals of a Fire Rating Wall:

Fire-rated walls are designed to provide a specific level of fire resistance. They play a crucial role in slowing the spread of fire and smoke, allowing for safe egress and emergency response.

Definition and Purpose of Fire-Rated Walls

Fire-rated walls are structures that have been tested and certified to resist the passage of fire for a certain amount of time. They serve to compartmentalize a building, thus containing fires within a limited area. The primary purpose is to safeguard the lives of inhabitants and to minimize property damage.

Materials in Fire-Rated Walls

Materials used in fire-rated walls are selected based on their ability to endure heat and resist burning. These materials may include:

• Gypsum board
• Concrete
• Bricks
• Protective coatings

Each material plays a role in achieving the desired fire resistance level and overall wall integrity during a fire event.

Understanding 1-Hour Fire-Rated Walls

A 1-hour fire-rated wall refers to a barrier designed to withstand the passage of fire for at least one hour. Building codes in Canada often determine where these walls are necessary, typically in commercial structures, multi-family residential buildings, and in designated egress areas.

The composition of these walls usually includes gypsum board or other materials that adhere to the strict guidelines set by the Underwriters Laboratories of Canada (ULC) or equivalent standards. The effectiveness of a 1-hour fire-rated wall is determined by its ability to maintain its structural integrity and to limit the temperature on the unexposed side to below a certain threshold, usually around 121 degrees Celsius.

Fire-resistance ratings are assigned after testing assemblies of specific construction materials and methods. For a 1-hour rating, the wall must include:

• At least one layer of 5/8-inch Type X gypsum board per side
• Studs spaced correctly according to the local building codes
• Appropriate fire-blocking materials

It is essential to note that the complete system, including the joint compound, fasteners, and how the wall is built, contributes to the rating. Electrical boxes, pipes, and ductwork passing through these walls require special attention to maintain the fire-rating. They typically require firestop systems or devices designed to prevent fire spread.

1-hour fire-rated walls are a critical component of passive fire protection, serving to contain fires and provide occupants with the time needed to evacuate safely. Proper installation and maintenance are crucial for ensuring that they perform as expected in the event of a fire.

Understanding 2-Hours Fire-Rated Walls

A 2-hour fire-rated wall serves as a critical element in the design of buildings, as it provides a significant level of protection against the spread of fire. These walls are constructed with materials capable of withstanding exposure to a specific temperature, as determined by fire resistance tests, for a duration of two hours.

Materials Used:

• Gypsum: Typically, layers of Type X gypsum board are used, which is thicker and more fire-resistant than regular gypsum.
• Concrete or Masonry: Heavier materials like concrete blocks or poured concrete can also achieve a 2-hour rating.
• Insulation: Mineral wool or fiberglass insulation is often included to improve fire resistance.

Testing and Certification:

• Standards: In Canada, the National Building Code (NBC) mandates testing according to ULC (Underwriters Laboratories of Canada) standards.
• Assessment: They undergo ULC S101, a standard fire endurance test which exposes the wall to a controlled fire reaching the same thermal conditions expected in an actual fire.

Construction and Compliance:

• Joints and Penetrations: Meticulous attention is given to joints, penetrations, and the sealing of gaps to maintain integrity.
• Supporting Structure: The supporting structure must also comply with the required fire-resistance rating.
• Inspections: Regular inspections are necessary to ensure ongoing compliance with 2-hour fire-rated standards.

Functionality and Safety:

• Compartmentalization: This type of wall is essential for compartmentalizing a building to prevent or slow the spread of fire and to safeguard egress routes.
• Load-Bearing: Some 2-hour fire-rated walls may also be load-bearing, which adds complexity to their design.

By adhering to stringent safety standards and regulations, 2-hour fire-rated walls enhance the protective measures within a building, offering more time for evacuation and for emergency services to respond.

Comparative Analysis

In analyzing the difference between 1-hour and 2-hour fire-rated walls, attention is paid to their performance in resisting fire and how each aligns with building code stipulations.

Fire Resistance Performance

A 1-hour fire-rated wall can resist the passage of flames and high temperatures for a minimum of one hour, providing a basic level of protection. 2-hour fire-rated walls, on the other hand, offer a higher degree of resistance, as they are designed to withstand fire exposure for a minimum of two hours. These ratings ensure that crucial structural components maintain their integrity during a fire, allowing more time for evacuation and emergency response.

The overall efficacy of fire-rated walls is tested in accordance with CAN/ULC-S101, “Standard Methods of Fire Endurance Tests of Building Construction and Materials.” During such tests, walls must remain intact and limit temperature rises on the unexposed side to specified thresholds.

Building Code Requirements

The National Building Code of Canada (NBCC) specifies when and where fire-rated walls are required based on building use, occupancy type, and size. For instance, a 1-hour fire-rated wall might be required between living units in a multi-family dwelling, while a 2-hour fire-rated wall is commonly mandated for separating different occupancies in mixed-use buildings or for protecting exit stairwells in high-rise structures.

Below is a table summarizing the typical applications for each fire-rated wall:

Fire Rating	Residential Applications	Commercial Applications	Special Considerations
1-hour	Unit separations in duplexes and townhomes	Separation of office spaces	May be used in areas with lower fire risk or where other protective measures are implemented
2-hour	Not typical in standard residential construction	High-risk areas such as boiler rooms, and separation of different occupancies	Used in scenarios requiring extended fire resistance for safety and structural integrity

These codes are periodically updated to reflect the latest research and technology in fire safety, and adherence is mandatory to ensure the safety and compliance of the building.

Installation and Inspection

When constructing 1-hour and 2-hour fire-rated walls, attention to detail during installation is critical to ensure they meet the required fire resistance standards.

1-Hour Fire-Rated Walls:

• Materials: They typically involve the use of Type X gypsum board, which should be at least 5/8 inches thick.
• Fastening: Screws or nails must be in accordance with the manufacturer’s specifications, usually spaced every 200 mm along framing members.
• Joints: Taped with fire-resistant joint compound.

2-Hour Fire-Rated Walls:

• Materials: May require thicker Type X gypsum board or additional layers.
• Fastening: Similar to 1-hour walls but may need additional fasteners or adhesive for multiple layers.
• Joints: Each layer’s joints should be staggered to avoid alignment and taped with fire-resistant joint compound.

Inspection Process:

• Documentation: Inspectors verify the appropriate materials are used based on building codes.
• Visual Inspection: Confirms correct installation techniques, proper fastening, and the absence of any penetrations.
• Seals: All utility penetrations are sealed with fireproof materials.
• Approval: Once compliance with the relevant fire-rating specifications is confirmed, walls are approved.

It’s essential for contractors to follow the prescribed practices and for inspectors to thoroughly assess the work to ensure the fire safety of the building.

Frequently Asked Questions

Understanding the difference between 1-hour and 2-hour fire-rated walls is critical for compliance with safety codes and the effectiveness of fire safety measures in buildings.

How do fire-rated wall assemblies differ between 1-hour and 2-hour classifications?

A 1-hour fire-rated wall assembly is designed to withstand fire for at least one hour before it compromises the wall, while a 2-hour fire-rated wall can resist fire for at least two hours, providing added time for occupants to evacuate and fire services to respond.

What are the construction requirements for a 1-hour fire-rated wall?

To meet the 1-hour fire-rated wall standard, the construction must include materials like fire-resistant drywall and insulation, with components assembled in a specific way to prevent the passage of flames and high temperatures for a minimum of one hour.

What constitutes the increased protection in a 2-hour fire-rated wall assembly?

The 2-hour fire-rated wall assembly incorporates additional layers or more fire-resistant materials, increased thickness of the wall components, and possibly supplementary fire-stopping products, which together extend the wall’s integrity during a fire to two hours.

Can you describe the significance of the time rating in fire-rated walls?

The time rating in fire-rated walls indicates the duration that a barrier can maintain its structural stability and integrity to contain a fire, providing a measurable period for evacuation and fire containment efforts.

What materials contribute to achieving a 2-hour fire-resistive rating for walls?

Materials such as thicker layers of gypsum board, fire-retardant-treated wood, or intumescent paint, among others, are used in combination to comply with the 2-hour fire-resistive rating, enhancing the wall’s capacity to withstand fire conditions for a longer period.

How does a 1-hour fire barrier differ from a 1-hour fire partition in construction standards?

While both are designed for fire-resistance, a 1-hour fire barrier is intended to restrict the spread of fire within a building and support structural loads, whereas a 1-hour fire partition typically serves to separate tenant spaces and is not designed to carry loads.