Passive Fire Design – Problems, Risks, References
Passive Fire Design – Problems, Risks, References
Passive fire protection includes fire rated walls, fire doors, fire collars, and intumescent coatings/sealants.
See also separate article “Passive Fire Design – Intumescent paint systems”
The Problems
Smoke can be forced under pressure through any gaps in passive fire construction. While most of these gaps are associated with cable and duct penetrations through fire walls, even the walls themselves have been found to be incorrectly built. These issues require design, inspection, and follow-up in the course of new work; and in alteration projects have the potential to create budget blow-outs for the unexpected remediation of existing work.
Problems arising out of the design of Passive Fire Protection have included budget blow-outs because it has been only “generically described” and inadequately allowed for under a Provisional Sum; where the scope of work has not been clarified by a specific schedule of requirements for penetrations; where intumescent coatings have been compromised by affixed framing for linings; where compliance verification has not been provided sufficient for the issue of a building consent; and where the co-ordination of the fire design information with the architectural documentation has been lacking, or misunderstood.
Problems arising out of the construction observation role have arisen out of failure to obtain timely verification of fire door compliance; failure to inspect work in detail; reliance on a representative inspection (or contractor’s declaration) to inform overall compliance; lack of co-ordination between the services consultants and others in respect of penetrations; inability to inspect in detail because of the intermittent nature of observation versus the ongoing construction; and a misunderstanding of the role of the Fire Engineer in respect of site observation.
Risk Management
If a fire engineer is engaged to provide a Fire Design Report, the other consultants are required to design and document in accordance with it and to provide verification of that. Where verification is beyond a standard solution provided by a supplier/installer or product data sheets, it will require to be reviewed by the fire engineer.
Don’t assume that because a fire engineer has been engaged, they will also provide passive fire protection advice. Fire engineering is a different discipline to passive fire protection, but many fire engineering design practices also offer passive fire protection advice.
If your client commissions a fire engineer, their scope should include input into any non-standard design situations, and a site observation role. Even if this requires a significant increase in the fire engineers’ scope of work, it is appropriate that the verification of fire compliance should lie with the consultant best placed to deal with it.
Some Building Consent Authorities have recently been asking for a ‘coordination statement’ from the Fire Design Report author to confirm that they have reviewed all Architectural, HVAC Mechanical, Lighting and Hydraulics documentation and verify compliance with the Report. This is a matter for the fire engineer, not the architect.
As part of the pre-design information gathering for existing buildings, consider a building survey to check fire stopping and other passive fire protection, including fire doors.
Passive fire constructions and fire-stopping situations should be detailed and/or scheduled based on the performance requirements of the Fire Design Report. This might be done by the fire engineer, or a passive fire protection designer, or the architect. If the latter, and you are unsure of any aspect of that report or how to meet its requirements, seek advice and input from the manufacturers of the systems or the fire engineer.
Work with reputable suppliers/manufacturers to check that your details are acceptable; get the input of the passive fire protection designer for non-standard situations.
Where there are acoustic performance requirements, workshop the design of these constructions with your acoustic and fire engineers. Site observation includes a review of the construction of passive fire elements. If you have not been engaged for that work, make that clear in your terms of engagement.
The relationship role between fire engineer and architect must be clearly and unambiguously recorded and adhered to. There should be no gaps in their respective oversight roles which could be exposed in any subsequent judicial inquiry into the cause and nature of a building fire resulting in loss of property and life. This is probably seen as being a statutory duty of care obligation for the building owner and their professional consultants under the HSAWA.
Reliance on a contractor’s and/or sub-contractors’ producer statement (PS-3 Construction) is not a guarantee that the works have been correctly completed.
Useful References
• In January 2019 Auckland City Council issued a position statement “AC1825 Auckland Council position statement for acceptance of fire stopping”. This is a useful document even if you aren’t working on Auckland City projects.
• Fire Protection Association of NZ website:
http://www.fireprotection.org.nz/home
• In September 2011 IPENZ issued Practice Note 22 which set out guidelines for documenting fire safety designs because of a concern about poor such documentation. It’s worth familiarising yourself with this document if you regularly work with fire engineers.
• In August 2019 The NZ Society of Fire Protection Engineers issued a draft of a proposed guide for Fire Engineering Construction Monitoring.
• ‘Build’ Magazine Issue 171, pages 39 to 60.
https://www.buildmagazine.org.nz/issues/show/action-on-passive-fire-protection
• BRANZ Guide to Passive Fire Protection in Buildings.