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CROSS Safety Report

Fire compartmentation detailing issues

Report ID: 1039 Published: 18 August 2021 Region: CROSS-UK


Overview

Two reports have been received concerning fire compartmentation detailing issues; one on the incorrect installation of fire batts and the other on the incorrect use of intumescent material.

Key Learning Outcomes

For designers, contractors and specialist installers:

  • Preventing the spread of heat and smoke between compartments is a core element of a fire safety strategy

  • Many services may need to pass through compartments; proprietary products are deployed to make good any voids created

  • It is critical that the products deployed to make good any voids created are used in accordance with the manufacturer's specifications. These reports indicate that it is commonplace for such products to be used in a manner that would render them ineffective in a fire situation.

For building owners and other persons responsible for commissioning mechanical and electrical work:

  • It is imperative that those responsible for managing buildings or specifying works understand that fire compartmentation might be affected by work such as replacing or adding cables, pipes or conduit
  • When engineers or installers create voids between compartments temporary arrangements may be required whilst the work is in process and the voids must be made good on completion of the work to the standard required for the compartment

Full Report

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Two reports have been received concerning fire compartmentation detailing issues; one on the incorrect installation of fire batts used to seal service penetrations in fire-rated compartment walls and the other on the incorrect use of an intumescent material used to seal service penetrations in floors.

One reporter is a local authority building surveyor who, from 2019 to the present, has been asked to assess fire compartmentation in newly-built and refurbished existing buildings owned by the authority. The other reporter is a construction supervisor.

Incorrect installation of fire batts

On inspection of several new builds and existing buildings, the reporter has identified fire batts that have been incorrectly installed. They say that the defective installations are endemic and not isolated occurrences. Figure 1 shows single thickness batts that have been cut to fit around services and into openings.

Photo shows single thickness fire batts that have been cut to fit around services and into openings
Figure 1: single thickness batts cut to fit around services and into openings

The joints between batts and between the structure and the batts have been sealed on one side only. The manufacturer's installation recommendations call for cut or exposed batt edges to be sealed and for joints in both faces to be sealed with intumescent mastic. In all cases, the installer was a specialist contractor with third party accreditation.

The reporter says that incorrect installation of these products compromises the integrity of fire compartmentation. Consequently, the compartments are unlikely to provide the designed level of fire protection.

The reporter says that incorrect installation of these products compromises the integrity of fire compartmentation. Consequently, the compartments are unlikely to provide the designed level of fire protection.

Incompatibility between intumescent material and insulation

100mm core holes were drilled between floor slab levels, within the dedicated cupboard forming the new riser. The copper pipework was installed immediately after the core holes were complete. Temporary works included the fire foam filling between the slab level core and the copper pipework by an approved accredited sub-contractor.

One day later, the temporary works were removed allowing the proprietary pipe insulation to be fitted to the copper pipework. The sub-contractor then applied the permanent fire stopping intumescent sealant on the same day the lagging was installed, assuming that this resulted in the restoration of the fire compartmentation.

A day after the permanent fire stopping intumescent sealant was applied, the reporter, as part of their continued design review and installation inspections between the main contractor and the fire stopping contractor, identified that the insulation wasn’t compliant with the intumescent material installation datasheet.

The installation design had specified a Class 0 lagging, but the intumescent material detail is only compliant with specified insulation, not the one used. The issue is that in the event of a fire, the sealant expands which would distort the (initially fitted) Class 0 insulation, whereas the specified material is rigid and the integrity would be maintained.

The issue is that in the event of a fire, the sealant expands which would distort the (initially fitted) Class 0 insulation, whereas the specified material is rigid and the integrity would be maintained

The design was therefore updated to include a compliant lagging. The sub-contractor removed the initial Class 0 insulation and replaced it with compliant material and then sealed the opening with the intumescent sealant in a single visit.

Underlying causes include poor training and lack of checking

The reporters say that the following are the underlying causes of these safety issues:

  • Some installers are poorly trained and do not understand the correct installation of the products. Improved training and education of the workforce are required.
  • Main contractors and clients rely on specialist contractors for installation and expertise without adequate checks on workmanship and adherence to technical requirements. Where there is a lack of in-house or third-party checks on correct installation, these defects may not be identified, leaving fire protection incomplete. More rigorous inspection is required.

Expert Panel Comments

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These are very common situations. Fire stopping is often carried out by people without the correct competence who then use the wrong methods or materials (or combination of materials). Workstreams are already underway to try and address this, by raising the competence requirements for managers of residential buildings (so that they know how to ensure that only competent people carry out the works) and of the people carrying out the work. 

Retaining evidence of fire stopping works

Fire resisting compartmentation issues are, unfortunately, regularly identified by Fire and Rescue Services during audits and are a regular fire safety deficiency and issue recorded in letters and legal notices to Responsible Persons.

Responsible Persons and those that manage or have control of premises, under The Regulatory Reform (Fire Safety) Order 2005 or other fire safety law outside of England and Wales, should ensure they not only use installers that are certified by a certification scheme for fire-stopping that has UKAS accreditation but they also ensure they receive and retain evidence and records of the fire stopping works to inform and support their fire risk assessment. This will assist when premises are audited by the enforcing authority.

In most cases a fire engineer is unlikely to be involved in this level of detail, but it does highlight the need for suitable levels of oversight.

Competence of specialists

Surveys commonly identify the use of proprietary fire stopping products/systems that are installed outside the bounds of application given by the manufacturer's specification. To the untrained eye, these alleged defects in fire stopping are not always obvious, so highlights the importance of competency for this specialist area of expertise.

These are very common situations, particularly where there are multi-service penetrations. Some contractors are moving away from large openings with multiple services, to single openings for each service which makes the provision of a fully tested system easier. It is easier to design and implement this on complicated schemes, where BIM is used. Of course, none of this deals with incompetence, but sometimes the overall design can make it easier for the installer to meet the tested system.

It is concerning that these defects have originated (in all cases) from specialist contractors with third-party certification. This report highlights the need for appropriate training and education for those carrying out this specialist area of work and the potential need for independent inspection of work by a competent person.

This report highlights the need for appropriate training and education for those carrying out this specialist area of work and the potential need for independent inspection of work by a competent person

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