Guide to Conversion of Traditional Buildings

2.9. Escape

Standard 2.9

Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, the occupants, once alerted to the outbreak of the fire, are provided with the opportunity to escape from the building, before being affected by fire or smoke.

2.9.1 Type of standard

Mandatory Standard

In the case of conversions, as specified in regulation 4, the building as converted shall meet the requirement of this standard (regulation 12, schedule 6).

2.9.2 Commentary

This standard, whether applied to the conversion of domestic or non-domestic buildings, is likely to have a significant impact on the fabric and character of traditional and historic buildings. The standard may have an influence on the existing historic spatial arrangements within a building and the fire resistance requirements of elements forming escape routes. It could also potentially affect the external envelope of the building, which, of course, should be avoided and only considered as a last resort.

The guidance in the Building Standards Technical Handbooks should be interpreted with sensitivity to avoid loss or damage to historic features.

It is therefore recommended that, for more important historic buildings in which the internal fabric is intact, fire engineering is included in the design of conversions and suitably qualified and experienced fire engineering specialists are appointed for this work.

In some circumstances it may be the case that, even with fire engineering, the provision of safe escape cannot be achieved without impacting significantly on a building’s historic character. Where this is the case, the suitability of the building for its proposed new use must be questioned. However, most buildings can be adapted successfully and there are many examples of Category A listed buildings that have been sympathetically converted to a new use while preserving their cultural significance.

However, it is possible that in many historic building conversions the nature, and size of the building will not warrant a full fire engineering approach. In such cases, the sympathetic alteration of the interior to improve its physical features for escape purposes, combined with other interventions such as enhanced automatic fire detection or automatic suppression systems, may provide a solution that meets the requirements of this functional standard.

By applying the guidance in BS 7974: 2019, Application of fire safety engineering principles to the design of buildings, CIBSE Guide E, BS 9999: 20017, or BS9991 2024 for residential buildings, it may be possible, for example, to compensate for deficiencies in escape route travel distances and combustibility of materials by the use of automatic fire detection and alarm systems, and automatic fire suppression systems. These systems will provide early warning to occupants of the outbreak of fire and intervention to control the fire, both of which can allow additional time for safe escape. Implementing a fire engineering solution can provide the occupants with the opportunity to escape from the building before being affected by fire or smoke, which is the essential requirement of the standard.

Where conversion of a building is not constrained by internal planning, such as when there is nothing of cultural significance like an original plan form or important historic finishes, implementation of the detailed guidance in the Technical Handbooks on passive escape measures should be included within the design. Nevertheless, while escape routes and associated features should be in accordance with the associated guidance that supports the standard (including non-combustibility requirements), an increase in the number of exits or their width may have a negative impact on the character of historic façades.

There are several specific issues where, to comply with the standard, there is the potential to impact negatively on a building’s traditional or historic character. It is important that these issues are considered because even small changes can affect the character of a building. Section 2.9.3 below outlines the most common examples.

In the past many historic buildings have been provided with refuge spaces on roofs and balconies, where people can wait for rescue by the fire and rescue service. This practice is no longer acceptable so new arrangements will be required. Furthermore, means of escape for disabled persons should be provided without relying on rescue by the fire and rescue service.

Note: Refuge spaces should not be confused with ‘temporary waiting spaces’ as detailed in the Technical Handbook guidance to this standard. The document - Practical Fire Safety Guidance – The evacuation of disabled persons from buildings, 2014 issued by the Scottish Government also provides information and guidance on fire evacuation of disabled persons from buildings.

Under fire safety legislation in Scotland, it is the responsibility of those persons who have control of, or safety obligations in respect of non-domestic premises, to ensure that arrangements are in place for an evacuation of the premises, if the situation requires it. This responsibility cannot be delegated to the Fire and Rescue Service. Each building should have an emergency fire action plan specifying the evacuation procedures for everyone, including disabled people, likely to be in the building.

Evacuation and fire-fighting lifts can aid with the evacuation of mobility impaired occupants. These lifts have a back-up power supply to avoid an interruption in operation if the primary power fails. Class A lifts are usually found in existing buildings with floor heights under 18m floor above the ground and have either an independent power supply or a separately fused circuit located in a fire-protected enclosure. Class B lifts are required in buildings with floors over 18m and have on independent secondary power supply.

However, lifts meeting the recommendation of BS9991, BSEN 81-20 and BSEN81-76 have traditionally been designed so when the fire alarm sounds it returns to the exit level with the doors open to allow occupants of the lift to escape. The lift is then managed by a competent person who switches the lift to manual control from the lift car to rescue persons on the upper floors. Where the building is not continually staffed, there may be an unacceptable delay in evacuating. This situation has been addressed by the new BSEN81-76 which allow an input signal to service “all defined floors” for evacuation.

2.9.3 Issues to be considered

Issue - Risks to historic / traditional buildings

1. Number of fire exits The provision of additional fire exits to traditional or historic buildings can be damaging to internal spaces and to the external character of the building.

2. Travel distances To adhere strictly to a maximum travel distance within a historic building may require alterations that are disruptive to spaces of architectural or historic significance. Factors that may allow longer travel distances are:-

• the provision of automatic smoke detectors when the building would not otherwise require them.
• the provision of a suppressions system
• where ceilings are so high that smoke is unlikely to affect the means of escape.

3. Escape windows (domestic) The provision of an openable window in upper storey apartments (4.5m or less above the ground) which is also large enough to escape through may require alterations to historic windows. The maximum height of 1.1 metre above the floor of the openable part may also be difficult to achieve in some situations where lowering of a sill height will affect the character of the building.

4. Headroom A headroom of 2 metres may be difficult to achieve in some attic conversions. A minimum clear headroom of 1.9 metres to a doorway in an escape route may be difficult to achieve in a traditional doorway. This will usually require alterations to the opening and to the door itself resulting in the loss of historic doors and frames.

5. Fire doors Doors in fire resisting walls are usually required to be fire resisting and self-closing to at least medium duration in non-domestic buildings and at least short fire resistance in domestic buildings. There is a presumption against replacement of historic doors, so sympathetic methods of upgrading of a historic door should be adopted to avoid significant changes to its character. See Fire Resistance of Historic Timber Panel Doors from Historic England and Institution of Fire Engineers. Uncontrolled self-closing devices that slam a door shut should be avoided as they tend to damage the door and frame.

6. Locks Historic ironmongery, such as locks and hinges, contribute to the character of a door. The code of practice ‘Hardware for fire and escape doors’ issue 5 2024 published by the Door and Hardware Federation and the Guild of Architectural Ironmongers may not be compatible with preserving the character of historic doors.

7. Temporary waiting spaces The formation of an obstructed temporary waiting spaces of more than 700mm by 1200mm on every escape stair landing may be difficult to provide without destructive alterations to existing spaces and fabric.

8. Protected zones and enclosures Protection of zones and enclosures to at least the fire resistance stated in the Technical Handbooks may lead to loss or alteration of historic finishes and doors.

9. Combustible escape stairs Creating a protected zone or lobby in non-combustible materials for every part of an escape stair (including the landing and floor) may have a significant impact on the stair and wider building if the escape stair is an important historic timber stair.

10. Junctions Fire stopping of junctions between escape routes and other parts of the building may require the removal of historic finishes.

11. Direction of doors (non- domestic) Where the occupant capacity is 10 or more for storage or factory buildings, or more than 60 for other buildings, doors across escape route should open in the direction of travel. This can mean alteration to the door and to adjacent spaces. Where the doors are in masonry arches, it may not be possible to change the direction of opening.

12. Signs and notices Signs and notices can be obtrusive and not in keeping with the character of traditional or historic buildings.

2.9.4 Recommendations to meet the standard

It is recommended that specialist advice for design and construction should be sought from those with appropriate heritage and fire expertise.

It may be appropriate to install an automatic fire suppression system (see guidance to standard 2.15) and an enhanced automatic fire detection and alarm system, for example a Category L1 to BS 5839- 1 2017, to ensure the earliest possible warning in the event of an outbreak of fire.

a) Fire risk assessments

Traditionally, prescriptive codes and guidance relating to means of escape has focused primarily on evacuation times with commensurate rules on maximum travel distances. It is often these rules that will determine the location of staircases and final exits. Therefore, in every case, there will be a need to carry out a full and detailed analysis to establish:

• all persons who may be at risk,
• the potential and inherent fire risks within the building,
• what control measures that may already exist and/or are expected to be provided within the building.

By using BS 9999 2017 or BS 9991, a risk profile can be established using occupancy characteristics and fire growth rates. The risk profile is a more accurate assessment of the fire risks involved, so the fire risk profile can be translated into appropriate travel distances and door widths – subject to ongoing good management in accordance with BS 9999 2017 Part 12 and BS 9991.

Limiting the maximum number of persons within a building, or parts of a building, at any one time may be a more acceptable alternative to installing new or wider exit doors that will damage historic fabric. This might provide a solution, particularly for larger public buildings used for assembly and entertainment. However, whilst this may initially be considered as an attractive option, it is often regarded as an unsatisfactory solution if the way a building is used changes in subsequent years.

b) Available safe egress time

When designing buildings for life safety, CIBSE Guide E and BS 7974 (with published documents 1-7) directs practitioners to ensure that the time available for escape, the available safe egress time (ASET), should be greater than the actual time needed to reach a place of relative safety, i.e. required safe egress time (RSET). This can be demonstrated by:

• modelling fire and smoke development to determine the onset of untenable conditions for persons in a building (to determine ASET),
• calculating the total sum of the fire detection/alarm time, the recognition / response time, and the travel time to a place of safety (to determine RSET),
• comparing the results.

This exercise may show that no significant changes are needed to ensure adequate escape routes in an existing building, even if it does not comply with the Technical Handbooks.

In the majority of simpler buildings, it is appreciated that this approach is unnecessarily complex and time consuming, and therefore the usual approach is to use accepted guidance in the Technical Handbooks as a yardstick and a means of determining the adequacy of provisions.

However, not all cases of variance from the guidance will require the appointment of a fire engineer. Reference could be made to ‘A simplified approach to alternative fire safety strategies’, Scottish Government (2010)16, or BS 9999: 2017 may provide a middle way by also allowing for more flexible design when additional fire precautions, such as automatic fire detection, fire sprinklers or smoke control systems etc, are installed.

c) Active systems

The standard already includes guidance on the implementation of active fire defence systems, such as automatic fire detection, alarms and fire suppression systems. Where necessary, weaknesses in means of escape may be sufficiently compensated for by enhancing fire detection coverage and/or installing fire sprinklers.

d) Improvements to means of escape

Where improvements to the means of escape are still required, there are several ways that these can be achieved without unduly damaging the historic character and fabric of a building, such as: -

• existing ground floor windows can sometimes, with care and diligence, be converted to suitably sized final exit doors that are in keeping with a building’s façade.
• staircases can be enclosed by the careful introduction of new doors and screens or, if the building is devoid of high fire loads and smoke is the principal concern, existing lightweight fire screens might be acceptable.
• Fire shutters can be particularly useful across wide and/or tall openings, such as at the base of large accommodation staircases. However, the aesthetics, cost of testing, maintenance, repair and replacement should be part of the decision about their suitability.
• minor improvements to existing separating walls can convert them into what can be considered compartment walls, potentially reducing unprotected travel distances.
• existing walls, doors and floors can be upgraded causing minimal disruption (see Section 2.1)

e) Timber stair and landing upgrades

When it is not be possible to remove existing timber stairs and install a non-combustible stair, consider mitigating measures that will enhance fire resistance duration including; -

• Application of fire retardant. The upper level of the stair can be impregnated with a fire retardant. The paint or varnish will need to be removed to allow full impregnation of the timber. Certification will be required from a specialist contractor for both product and installer. If the specialist contractor cannot provide the certification, more extensive upgrade work may be required.
• Fire protection to the underside of the stair - underline stair with plasterboard to provide 60 minutes fire resistance duration. This reflects the research commissioned by the UK Government under the Fire Performance of Escape Stairs project which was undertaken by BRE. This demonstrated the ability of suitably treated staircases to fulfil their required function in the event of a fire.
• Similar measures may be considered when (due to a conversion) a timber stair and landing which may have been regarded as private becomes a common stair and landing. Additional considerations such as size and type of timber, height of building, travel distance and occupancy numbers, and fire safety measures provided such as automatic fire suppression systems, will also impact the necessary level of fire protection.

This flow chart from ‘A simplified approach to alternative fire safety strategies’ by the Scottish Government sets out the five key design features that can influence alternative solutions for compliance with mandatory standards. For each of the design factors, the following guidance provides a structured approach and identifies risk.

Factors to be considered for alternative solutions proposed to satisfy mandatory standards;

Consider changing the number or type of occupants at risk?

Can the location or amount of fuel be changed?

Can you reduce fire spread?

• Size and number of fire compartments
• Automatic life-safety fire systems
• Smoke management system

Can you reduce evacuation time?

• Improve communication systems
• Simplify the escape routes
• Provide more exits
• Reduce travel distances

Can a place of temporary safety be provided within the building?

Is equivalent or higher standard of safety achieved?

• Yes
• No/unsure

If No/Unsure - Consider the appointment of a fire engineer to develop alternative strategy/solution

If Yes - Mandatory Standards satisfied

The diagram illustrates a decision‑making process for developing alternative fire‑safety solutions when standard approaches may not be viable. It begins by identifying a range of factors that can be adjusted – such as occupant characteristics, fuel load, fire‑spread mitigation, evacuation improvements, and the provision of temporary safe areas. These considerations help shape a tailored solution intended to enhance overall safety. A fire engineer may be appointed to help design these alternatives. The critical step is then to determine whether the resulting strategy achieves an equivalent or higher level of safety than the mandatory standards require. If it does, the mandatory standards are considered satisfied; if not, the process loops back to reassess and refine the proposed measures.

f) Ironmongery and signage

Deficiencies in features such as locks on doors, low headroom, signs and notices etc, can sometimes be compensated for with the provision of enhanced supervision and stewarding, particularly in public buildings such as museums and galleries. The fire strategy plans should indicate which doors need to be manually closed and specify the rooms being managed. This ensures that, in the event of staff shortages, sections of the building can be temporarily closed and the doors securely latched.

Hold-open devices on inward opening doors across escape routes may be considered, even when these doors are required to be fire resisting and self-closing. This is because it might not be necessary for all fire-resisting doors to close immediately upon actuation of the fire alarm, with some operating on a delay or locally placed smoke detectors.

The hold-open devices may cause a door to warp if positioned on the leading edge of the bottom rail (as shown in Illustration 25), because the self-closing device on the opposite corner is working against it. A swing-free or hold-open closing device which responds to the fire alarm would avoid this issue. All of these solutions will clearly rely upon good levels of supervision and management and approval of authorities with jurisdiction, particularly the local fire authority. Further information on doors and door devices can be found in Historic Environment Scotland’s Guide for Practitioners 7: Fire Safety Management in Traditional Buildings (2010).