Fire protection to the structural frame of the building and fire retardant coatings

Question 1

Describe each of the following methods of providing protection to structural timber:
a) Sacrificial timber (3 marks)
b) Insulating boards (3 marks)

Answer 1

Definition: Sacrificial timber involves adding extra layers of wood to a structural timber element that are intentionally designed to char and burn away in a fire.

Function: As the outer layers char, they form a protective barrier that insulates the inner core, slowing down heat penetration and maintaining the load-bearing capacity of the structural timber for a longer time.

Use: Common in heavy timber construction, where increased dimensions provide natural fire resistance without the need for additional fireproofing materials.

Definition: Insulating boards are non-combustible panels (e.g., calcium silicate, gypsum-based, or mineral boards) applied to timber to protect it from direct exposure to fire.

Function: These boards act as a thermal barrier, preventing or delaying heat from reaching the structural timber, thus preserving its strength during a fire.

Application: Used in both concealed and exposed timber structures where enhanced fire protection is needed to meet building regulations and fire resistance ratings.

Question 2

a) Explain how the thickness of a steel structure affects its fire resistance and the amount of
structural fire protection required. (2 marks)
b) Explain, using examples, how the shape of a steel structure can affect the performance
of fire protection systems. (4 marks)

Answer 2

The thicker and heavier a steel section becomes the longer it will take to heat up, therefore the
amount of structural fire protection required to control the steel temperature to below the critical
level will be less than would be required for a thin lightweight section.

The shape of a steel structure affects how, for example, thin film coatings perform in fire conditions.

Steel structures with straight edges allow for thin film intumescent coatings to expand and insulate steel in a uniform way without cracks.

Hollow round sections and the round openings in cellular beams can cause the intumescent paint to crack when activated by heat. for cellular beams this can expose the residual web post to be exposed to temperatures above critical. This web post is a common area of failure in fire conditions.

Question 3

State the three main types of intumescent coatings used on steel structural designs and give
an example of a situation where each would be used. (6 marks)

Answer 3

1. Water-Based Intumescent Coatings
   Description: These are environmentally friendly coatings that expand when exposed to heat, forming an insulating char layer to protect steel.

Example Use: Ideal for internal environments like office buildings or schools, where humidity and weather exposure are minimal.

2. Solvent-Based Intumescent Coatings
   Description: These coatings use organic solvents and are more resistant to moisture and humidity than water-based types.

Example Use: Suitable for semi-exposed or humid environments, such as warehouses or car parks, where some weather or moisture exposure occurs.

3. Epoxy-Based Intumescent Coatings
   Description: Highly durable and resistant to harsh environments; often used in industrial-grade fire protection.

Example Use: Commonly used in offshore platforms, petrochemical plants, or industrial facilities, where extreme weather or corrosive conditions exist.

Question 4

Describe the inspection processes to be applied during the installation of board systems. (6
marks)

Answer 4

Check specified products, check system/s to be used, check board thicknesses required, check the quality and appearance of boards, check the components are those to be used with the board system, check packaging of adhesive and use by dates, check components are not damaged and check steelwork is satisfactory for the installation specified.

Question 5

Describe the inspection processes to be applied during the installation of board systems. (6
marks)

Answer 5

1. Verification of Materials
   Check all materials (boards, fixings, adhesives, etc.) against manufacturer specifications and ensure they are approved for fire protection use.

Ensure materials are undamaged and stored correctly to prevent moisture absorption or warping.

2. Surface Preparation
   Inspect steel surfaces to ensure they are clean, dry, and free from rust, grease, or debris before board installation.

Confirm whether any primer or base coat is required and correctly applied.

3. Fixing Methods
   Check that the correct fixings (screws, brackets, clips) are used as per the manufacturer’s guidelines.

Inspect the spacing and alignment of fixings to ensure the boards are securely and uniformly attached.

4. Joint Sealing and Detailing
   Ensure joints between boards are properly sealed with approved fillers or tapes to maintain fire integrity.

Inspect corners, edges, and penetrations (e.g., around services) for correct fire-stopping details.

5. Thickness and Coverage
   Verify that the required board thickness is used throughout to meet the specified fire resistance rating.

Ensure full coverage of the steel section, with no exposed areas or gaps.

6. Documentation and Sign-Off
   Maintain detailed records of inspections, material batch numbers, and installation checks.

Have the installation signed off by a qualified fire protection inspector or third-party certifier as needed.