Firestop, Fireproofing, and Smoke Containment

Fire Stops, Fireproofing, and Smoke Containment

Chapter Introduction

This chapter covers passive fire protection systems, a distinct field from active protection (sprinklers, alarms). As a heat and frost insulator, you will be called upon to install, repair, or replace insulating materials in buildings where compartmentation and fire resistance requirements are critical. The National Building Code of Canada (NBCC) and Canadian Standards Association (CSA) standards govern this work. Your role is not limited to installing thermal insulation; you must understand how your materials interact with fire stop systems and how to preserve the integrity of fire barriers during your interventions.

1. Fundamental Definitions

1.1 Fire Resistance (FR)

Fire resistance is the ability of a building element to withstand exposure to fire for a specified duration while continuing to perform its structural and separation functions. It is expressed in minutes (45, 60, 90, 120, 180) and determined according to CAN/ULC-S101 (Fire Resistance Tests for Building Construction Materials).

Three criteria are evaluated simultaneously:

1.2 Fire Resistance Rating (FRR)

The FRR is the rating assigned to a building element after testing. It is expressed in minutes and corresponds to the time during which the element satisfies the criteria above. For example, a wall with an FRR of 90 minutes will withstand a standard fire for 90 minutes before failure.

1.3 Fire Stop

A fire stop is a complete system (material + labour) installed in a penetration (opening) made in a fire barrier to allow the passage of services (piping, conduits, cables). It must restore the FRR of the barrier for a specified duration.

1.4 Fire Compartment

A fire compartment is a subdivision of a building bounded by elements having a minimum FRR, designed to limit the spread of fire and smoke. Heat and frost insulators must understand that every penetration in these compartments is a potential weakness.

1.5 Fireproofing

Fireproofing is the treatment of combustible materials (wood, steel, fabrics) to delay ignition and slow flame spread. For steel, fireproofing (intumescent paint or boards) aims to keep the steel temperature below the critical threshold of 538 °C (1000 °F) to preserve its load-bearing capacity.

1.6 Smoke Containment

Smoke containment is the set of measures designed to prevent the migration of toxic and hot smoke toward evacuation routes and adjacent compartments. Smoke is responsible for the majority of fire-related deaths. Smoke barriers, fire dampers, and fire-rated expansion joints play a crucial role.

2. Regulatory and Code Framework

2.1 National Building Code of Canada (NBCC)

The NBCC is published by the National Research Council of Canada (NRC). It is adopted, with or without modifications, by the provinces and territories. The relevant sections for the heat and frost insulator:

2.2 Material Classification Standards

2.3 Key NBCC Rules

Article 3.1.5.12 : Thermal insulation must be non-combustible or protected by a non-combustible material if the surface temperature may exceed 90 °C.

Article 3.1.5.14 : Thermal insulation made of plastic foam must be covered by a non-combustible material (gypsum, plaster) with a minimum thickness of 12.7 mm (½ in.).

Article 3.6.4.2 : Penetrations in fire separations must be protected by a fire stop system conforming to CAN/ULC-S115, with an F rating (fire resistance) at least equal to the FRR of the penetrated barrier.

Article 3.6.4.3 : Penetrations by electrical cables must be protected by fire stop systems tested according to CAN/ULC-S115, with an FT rating (fire resistance + smoke tightness).

3. Types of Fire Stop Materials

3.1 Sealants and Caulking

Fire stop sealants are paste-like products applied by gun or trowel. They are classified into two categories:

3.2 Mortars and Lightweight Concretes

Fire stop mortars are dry mixes to be mixed with water. They offer high mechanical strength and are suitable for large openings. Their density ranges from 400 to 1200 kg/m³.

3.3 Boards and Blankets

Fire stop boards are manufactured from mineral wool (rock wool or slag wool) treated with binders. They are used for large openings, linear joints, and ducts. Their typical density is 100 to 200 kg/m³.

3.4 Fire Stop Pillows

Fire stop pillows are flexible blocks of encapsulated intumescent foam. They allow for rapid modifications (adding/removing cables) without special tools. They are reusable.

3.5 Intumescent Paints

Intumescent paints are applied to structural steel. Under heat, they expand to form an insulating charred layer. The dry film thickness is calculated based on the section factor (A/V) of the steel section.

3.6 Fire Stop Collars

Fire stop collars are metallic sleeves containing an intumescent insert. They are installed around plastic pipes passing through a barrier. In the event of a fire, the insert expands and crushes the pipe, sealing the opening.

4. Installation Principles and Procedures

4.1 Pre-Installation Assessment

Before any fire stop installation, you must:

4.2 Surface Preparation

4.3 Fire Stop Installation

General procedure for an intumescent sealant:

Procedure for a fire stop collar:

4.4 Marking and Documentation

Each fire stop installation must be identified by a label indicating:

This documentation is essential for future inspection and maintenance.

5. Calculations and Sizing Factors

5.1 Section Factor (A/V)

The section factor is the ratio of the exposed surface area of the steel (A, in m²) to its volume (V, in m³). It is expressed in m⁻¹. The higher this factor, the faster the steel heats up, and the thicker the protection must be.

Formula: A/V = (exposed perimeter) / (cross-sectional area)

Example: For a HEA 200 beam:

5.2 Protection Thickness

The thickness of intumescent paint is determined from tables provided by the manufacturer, based on:

General rule: The higher the A/V, the greater the required thickness. An increase in FRR from 60 to 120 minutes may require double the thickness.

5.3 Annular Space Calculation

The annular space is the distance between the pipe and the edge of the opening in the barrier.

Formula: Annular space = (opening diameter − pipe diameter) / 2

Example: 150 mm opening, 100 mm pipe:

This space must be filled with the appropriate fire stop material. If the annular space exceeds the maximum tested value (often 50 mm), you must use additional backing material or a different system.

5.4 Calculating Pipe Coverage Length

For plastic pipes passing through a barrier, an exposed pipe length is required on each side of the barrier. This length, generally 300 to 600 mm, allows the pipe to melt and deform without pulling the collar out of the barrier.

6. Structural Steel Fireproofing

6.1 Why Fireproof Steel?

Steel loses its mechanical strength at high temperatures:

The NBCC requires structural steel members to have a minimum FRR depending on the occupancy and building height (for example, 45 minutes for a 3-storey building, 120 minutes for a building over 12 storeys).

6.2 Fireproofing Methods

6.3 Intumescent Paint Application Procedure

Critical point: The dry film thickness must be verified on every member. A 10% under-thickness can reduce the FRR by 20 to 30 minutes.

7. Smoke Containment

7.1 Smoke Barriers

Smoke barriers are vertical or horizontal assemblies designed to limit smoke migration. They do not necessarily have an FRR, but must be smoke-tight and have sufficient mechanical stability.

7.2 Fire Dampers and Smoke Dampers

Fire dampers are installed in ventilation ducts passing through fire separations. They close automatically at a temperature of 74 °C (165 °F) to prevent fire spread.

Smoke dampers close upon signal from the smoke detection system. They are tested according to UL 555S.

7.3 Fire-Rated Expansion Joints

Fire-rated expansion joints are installed in building expansion joints. They allow thermal and seismic movement while maintaining fire and smoke tightness. They are tested according to CAN/ULC-S115 with cyclic movement requirements.

7.4 The Heat and Frost Insulator's Role in Smoke Containment

When installing thermal insulation on piping passing through barriers, the heat and frost insulator must:

8. Specific Requirements for Thermal Insulation

8.1 Insulation and Fire Resistance

The NBCC classifies thermal insulation into two categories:

8.2 Insulation on Piping Passing Through Fire Stops

When insulated piping passes through a fire barrier, the fire stop system must be designed to account for the insulation. The options are:

Caution: Insulation can act as a wick, spreading fire along the pipe. CAN/ULC-S115 tests include configurations with and without insulation.

8.3 Protection of Plastic Foam Insulation

Plastic foam insulation (polyurethane, polystyrene) is combustible and produces toxic smoke. The NBCC requires:

9. Inspection and Maintenance Procedures

9.1 Visual Inspection

Fire stop inspection must be carried out:

Points to check:

9.2 Fire Stop Repair

Repairs must use the same system as the original, or an equivalent system tested for the same configuration. It is prohibited to mix products from different manufacturers without validation by testing.

9.3 Documentation

The fire stop register must include:

10. Pitfalls to Avoid

11. Exam Tips

12. Summary

13. Review Questions

This chapter prepares you for the Red Seal exam questions on passive fire protection. Master the standards, calculations, and installation procedures to pass your exam and practice your trade safely.