How Fire Engineering Saves Projects from Costly Redesigns
Late-stage fire safety issues are one of the leading causes of design changes and programme delays.
17 September 20244 min readFire Safety Services
Fire Safety and the Cost of Late Discovery
Late-stage fire safety issues are one of the leading causes of design changes and programme delays on UK building projects. Staircase configurations that do not comply with means of escape requirements, floor layouts that exceed travel distance limits, external wall specifications that breach regulation 7(2), sprinkler requirements that were not anticipated — these are problems that cost thousands of pounds to resolve at RIBA Stage 2 and hundreds of thousands to resolve at Stage 4 or 5.
The pattern is consistent across project types: fire engineering is deprioritised during the early design stages, the design progresses without fire safety input, and fire safety issues are discovered late — often at building control submission, Gateway 2, or (in the worst cases) during construction. At that point, resolving the issue requires unwinding design decisions that have already cascaded through the project.
Common Late-Stage Fire Safety Problems and Their Costs
The most frequent fire safety issues that generate costly redesigns include:
Single versus dual staircase — a building designed around a single core where a fire engineer concludes that two staircases are required under BS 9991 or NFCC guidance. Identified at Stage 2: the second core is incorporated into the concept. Identified at Stage 4: the structural engineer must redesign, the architect must reconfigure floor plates, saleable floor area is lost, and planning may need to be revisited.
Travel distance failures — escape corridor layouts that exceed maximum distances to protected escape routes. Identified at Stage 2: core position adjusted. Identified at Stage 4: entire floor plate may need reconfiguration with cascading cost and programme implications.
External wall non-compliance — for buildings over 18 metres, external wall systems must comply with regulation 7(2) which restricts the use of combustible materials. A cladding or insulation system specified without fire engineering input that is subsequently found to be non-compliant requires replacement — potentially after procurement, delivery, or installation.
Sprinkler requirement not anticipated — discovering at Stage 4 that sprinklers are required has a cascade effect. It changes the required water storage and pump room provision, the ceiling void depth requirements, the structural coordination, and — if the design was taking credit for trade-offs that sprinklers enable — potentially the entire escape strategy.
Firefighting shaft position — for buildings over 18 metres, firefighting shafts (containing firefighting staircase, lobby, and lift) must be positioned to serve all floor areas. A shaft in the wrong location identified at Stage 4 may require structural changes to achieve the required coverage.
The rule of thumb in construction cost management applies equally to fire safety: a problem costs 1x to fix at concept, 10x at detailed design, 100x during construction, and 1000x after completion.
How Fire Engineering Prevents Redesigns
A fire engineer appointed at RIBA Stage 2 participates in the development of the design concept, reviewing layouts as they develop and flagging fire safety issues before they become embedded in the design. The fire engineer's input at this stage is not about adding fire safety features — it is about ensuring that the design concept is fundamentally fire-safe, so that the detailed design can proceed without the risk of late-stage discoveries.
At Stage 2, the fire engineer establishes the fire safety strategy — the escape route philosophy, the compartmentation concept, the staircase requirement, and the sprinkler and smoke control approach. This strategy then constrains the design in a controlled way, preventing decisions that would create problems later.
Gateway 2 and Programme Risk
For higher-risk buildings, the Gateway 2 process adds a specific category of redesign risk. If the BSR identifies fire safety deficiencies in the Gateway 2 submission — including an inadequate fire strategy — the gateway is not passed and construction cannot commence. The developer must revise the submission, potentially revise the design, and resubmit. Each iteration adds weeks or months to the pre-construction programme.
A fire strategy developed from Stage 2, refined through Stage 3 and 4, and submitted as a complete, well-structured document at Gateway 2 significantly reduces the risk of BSR queries and resubmissions. The fire engineer who has been involved in the project from the outset knows the design intimately and can produce a Gateway 2 submission that addresses all the BSR's likely questions proactively.
Frequently Asked Questions
How does early fire engineering appointment reduce project cost?
Early appointment allows fire safety issues to be resolved during design, when changes are cheap. It prevents late-stage redesigns, avoids procurement and construction rework, reduces Gateway 2 programme risk, and allows the design to benefit from fire safety trade-offs — such as increased travel distances where sprinklers are provided.
What is the most common fire safety cause of building redesigns?
Staircase configuration — specifically the discovery that a building requires two staircases where only one was planned — is one of the most common and most expensive. Travel distance failures and external wall non-compliance are also frequent sources of late-stage redesign cost.
Can fire engineering input reduce construction costs?
Yes, in several ways. Where sprinklers are incorporated from the outset, trade-offs in other fire safety provisions can reduce structural fire protection costs, simplify compartmentation, and allow more efficient escape route layouts. A fire engineer who understands these trade-offs can optimise the design to minimise overall fire safety cost.
At what stage is it too late for fire engineering input to prevent redesigns?
By RIBA Stage 4, most design decisions have been made. A fire engineer appointed at this stage can document the fire safety position but has limited ability to change it. Stage 5 (construction) is essentially too late for anything other than responding to problems as they arise.
How do I make the case for early fire engineering appointment to a developer client?
Frame it as risk management and programme certainty. The fee for fire engineering from Stage 2 is a fraction of total professional fees. The cost of a single late-stage staircase redesign or a Gateway 2 rejection can be tens or hundreds of times the fire engineering fee. Early appointment is insurance against a specific, well-documented category of project risk.
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