What is the process for obtaining fire protection for a mezzanine floor?

Fire protection for a mezzanine floor is obtained through a documented process of assessment, design, approval, installation and inspection. The required protection depends on the building’s use, occupancy, floor arrangement, escape strategy, fire risk assessment and the requirements set by the building control body. A suitable system may involve fire-resisting boards, encasement, an assessed coating system, sprinklers or a combination of measures.

1. Arrange an initial assessment

The process starts with a review of the proposed or existing mezzanine floor and the building around it. This should be completed by competent specialists alongside the project designer and, where appropriate, the building control body. The assessment normally considers:

• the purpose of the mezzanine and the activities carried out on it;
• the number of people likely to use the floor;
• the building’s construction, height, size and existing fire precautions;
• the position of stairways, exits, protected routes and openings;
• the materials used in the floor, beams, columns and underside construction;
• the likely fire load, including stored goods, equipment and processes; and
• access requirements for firefighting, evacuation and emergency services.

An existing fire risk assessment should be reviewed rather than treating the floor as a separate feature. Adding a mezzanine can alter travel distances, compartmentation, smoke movement, escape capacity and the way occupants use the building.

2. Confirm the required fire performance

The design team must establish the fire performance required for each relevant part of the structure. This is not necessarily the same for the floor deck, supporting steelwork, columns, stairs, partitions and service penetrations. The required level is determined by the approved design and applicable building regulations, rather than by a standard product choice.

Fire resistance is generally considered in terms of the ability to maintain stability, integrity and insulation for the period specified by the design. Structural steel, for example, may need protection to prevent it losing strength during a fire. The underside of the floor may also need to resist the passage of flames and hot gases, while openings around services must be treated so they do not undermine the protected construction.

Building control may request calculations, drawings, product information, fire strategy details and evidence that the proposed solution is suitable for the particular construction. It is important to obtain this agreement before installation, because changing the system after work has started can cause delay and additional cost.

3. Select an appropriate protection method

The protection method should be selected after the required performance and site constraints are understood. Common approaches include:

• Fire-resisting board systems: specialist boards can protect the underside of a floor or enclose structural members. The board type, thickness, fixing method, joints and supporting framework must match the tested or assessed system.
• Encasement systems: beams and columns can be enclosed with suitable fire-resisting materials. Particular attention is needed at joints, corners, base details and connections.
• Intumescent coatings: these coatings expand when exposed to heat and are applied to suitable steelwork in accordance with a specified system. Surface preparation, dry film thickness, environmental conditions and inspection records are all important.
• Sprinkler protection: where required by the fire strategy, sprinklers can form part of the overall solution. Their design must account for the mezzanine layout, obstructions, storage arrangements, water supply and maintenance requirements.
• Compartmentation and fire-stopping: fire-resisting walls, ceilings, doors and seals may be needed to limit fire and smoke spread. All service penetrations, cable routes, ductwork and junctions must be detailed and sealed appropriately.

A product that has been tested in one arrangement is not automatically suitable for a different construction. For example, changing the board support, steel section, coating thickness, fixing pattern or floor build-up can affect performance. The proposed system should therefore have appropriate test evidence, an assessment or certification covering the intended application.

4. Prepare the design and obtain approval

The designer should produce clear drawings and specifications showing the areas to be protected, the materials to be used, the installation details and the required finish. The documentation should identify interfaces with stairs, handrails, walls, ceilings, doors, lighting, ventilation and other services.

These details are submitted to the relevant approval body as part of the building control process where required. The fire strategy and fire risk assessment should remain consistent with the proposed arrangement. If the building is occupied or the work affects existing escape routes, a temporary protection and access plan may also be necessary.

Approval should be recorded in writing, together with any conditions or inspection requirements. Approval of the overall project does not remove the need to follow the manufacturer’s installation instructions or to retain evidence of the products and processes used.

5. Check the structure and prepare the site

Before fire protection is installed, the supporting structure and surfaces should be checked. Steelwork may need cleaning and preparation before a coating is applied. Board systems require suitable, stable supports, and the underside of the floor must be accessible. Any corrosion, damage, contamination, water ingress or unapproved alterations should be dealt with before protection work begins.

Services and other obstructions should be identified in advance. Moving cables, pipes, ductwork or lighting after protection has been installed can create unprotected gaps. Where work is taking place in an operating workplace, the method statement should cover segregation, dust control, working at height, hot works, access, fire watch arrangements and the effect on normal evacuation procedures.

6. Install the system in accordance with its specification

Installation should be carried out by suitably trained and experienced operatives using the specified products and methods. The installer should follow the approved drawings and manufacturer’s instructions, including requirements for preparation, fixing, overlaps, joints, curing and environmental conditions.

Particular care is needed at interfaces. Protection should be continuous around structural connections and should meet adjoining walls, ceilings and fire-resisting elements without leaving concealed voids. Service penetrations should use compatible fire-stopping products, installed in the correct configuration. Unauthorised substitutions or site modifications should be referred back to the designer before they are made.

For an intumescent coating, quality control may include checking the substrate, primer compatibility, wet and dry film thickness, application conditions and the condition of the finished surface. For board or encasement systems, checks may include the board type, fixing centres, joint treatment, edge protection and the continuity of the enclosure.

7. Inspect, test and document the completed work

Completion should be verified by inspection against the approved design. Depending on the system, this may include visual checks, thickness measurements, photographic records, inspection of concealed details before closure and confirmation that fire-stopping has been installed correctly.

The handover file should normally include the approved drawings, product data, installation records, certificates or declarations of performance, inspection results, photographs and details of any variations. It should also identify the limits of the protection system and any restrictions on future alterations.

Building control or another appointed competent person may need to inspect the work before it is covered or before the area is brought into use. Any defects or incomplete items should be corrected and recorded before final sign-off. Fire protection should not be considered complete solely because the materials are present; the installation must provide the performance intended by the design.

8. Maintain the protection after handover

Fire protection needs to remain effective throughout the life of the mezzanine floor. The responsible person should include it in routine workplace inspections and the fire risk assessment. Checks should look for impact damage, corrosion, coating deterioration, missing boards, open joints, unauthorised penetrations, alterations to partitions and changes in the use or storage of the area.

Sprinklers, alarms, emergency lighting, fire doors and other active or supporting systems require their own inspection and maintenance arrangements. Any alteration that affects the floor, its supports, escape routes or services should be reviewed before work starts. Repairs should use compatible materials and should be recorded in the maintenance file.

The most reliable route is to involve the fire protection specialist, structural designer and building control body at the planning stage. Able Racking can help coordinate the practical assessment, documentation and installation requirements for a mezzanine floor, ensuring that the selected solution is suitable for the building and supported by clear inspection and handover records.