Proposed additional guidance within 2.0.7 ‘Alternative approaches’.
‘Reasonably practicable’ in the context of identifying risks and implementing proportionate mitigation measures.
For historic buildings and traditional buildings, which also require sensitive application of the standards, the judgement of what is reasonably practicable must be made in a wider context and recognising that it may be difficult for existing buildings to be reasonably and practicably altered to meet all aspects of current standards. There is no prescribed process for reasonably practicable which can cover all eventualities and situations, however, some commonplace risks as part of the holistic ‘weighing up’ or professional and competent judgment of risk(s) versus proportionate measures to minimise risk(s) to life in the context of existing or traditional buildings, are provided within the listed HES documents above with some notable risk factors also highlighted below.
Notable risk factors which should be considered in conjunction with Historic Environment Scotland guidance documents listed above and the non-domestic technical handbook guidance, in the context of conversion of traditional buildings to hotel use are as follows:
- A traditional or historic building will generally have linked cavities or voids. Unless all linings are removed (which may be impractical for both heritage and cost reasons), it is difficult to adequately identify and firestop these. The common construction of walls lined with lath and plaster on timber straps fixed to the masonry, leaving a cavity presents a risk of rapid spread once the flame breaches the wall and ceiling linings. The cavities often link with those present in floors and throughout a building, giving an easy path for fire spread. The fire resistance of floor constructions will often be compromised by the presence of such cavities but sealing the space can be disruptive and may interfere with the natural ventilation necessary to maintain the timber elements in good condition.
- Complexity of the floor plan and routes of escape, including floor height above ground level and travel distances and exit choices.
- Occupancy levels of the building.
- The need for individual appraisal of the building under consideration is paramount and required to understand the forms of construction and connection of voids in what can be complex buildings.
- The poorer fire performance of some components and traditional materials to modern standards including as a result of condition with age and maintenance, such as lath and plaster. Traditional plaster, while theoretically giving an adequate level of fire resistance, its condition will vary meaning performance in fire may be unpredictable.
- Forms of construction used such as traditional buildings with timber structures, floors and walls.
- The extent and completeness of compartment walls and floors. It is common for inherent weaknesses in fire integrity to occur: compartments may be incomplete, boundaries between elements (such as floors and walls) may not be sealed and openings in compartment walls may have doors with inadequate period of fire resistance.
- Highly complex series of different periods of build, differing construction techniques may make it difficult to determine the design and construction which leads to challenges in providing elements to current standards such as separating walls with adequate fire resistance, travel distances or escape routes. Alterations for services may also have compromised fire safety provisions (such as compartment walls being punctured) for example by electrical installations or provision of ventilation or heating services.
- Combustible linings or finishes.
- Large, interlinked roof voids.
- Fire resistance of doors.
- Electrical wiring.
- Unprotected structures/ structural elements.
- Risk of external fire spread, particularly those buildings with combustible facades
- Location (remoteness/access) of the building when considering Fire and Rescue operations
- Knowledge of designers, contractors and verifiers involved in the work. It is recommended that contractors have experience of traditional construction techniques and designers hold specialist accreditation.
Conversion of traditional buildings to be used as hotel accommodation is currently subject to notification under Section 34, where local authorities require to notify the Building Standards Division of such applications being made for building warrant and this will remain as an additional ongoing check and balance on the appropriate qualification and experience of the local authority verifier.
Conversion of a traditional building can be challenging and specialist advice may often be needed on specific risk topics, therefore the performance/risk-based approach requires to also consider any need for 3rd party specialist advice/involvement. These buildings carry inherent risks which may not be immediately apparent even to professionals who are not specialist in that field.
Unless the designer has the ability to strip a substantial proportion of the linings and finishes within an existing building then it is very difficult for them to know where all of these risk elements might be and the extent to which they might compromise the performance of a fire-engineered solution.
Recommendations for improving fire safety, including possible solutions for deviations to the guidance
- Where solutions depart from those in guidance, it may be more appropriate to install an automatic fire suppression system (see guidance to standard 2.15) and a Category L1 automatic fire detection and alarm system to BS 5839-1: 2017 to ensure the earliest possible warning in the event of an outbreak of fire.
- Suppression is an option in traditional buildings with hidden voids or where fire protection does not meet current standards or where suppression is proposed as part of a fire engineered design solution, as a compensatory feature for departures from standards or guidance.
- Ensure specialist advice is sought (for example designers, contractors and verifiers) and detailed, recorded on-site investigations are undertaken.
- Proposals verified by 3rd party specialists (heritage and fire), particularly for those situations where complex and interlinked factors present a high risk to occupants.
- Relining of escape routes and upgrading of other elements to improve fire performance, if practicable.
- While it may be possible to improve the passive fire performance of specific elements, there is likely to be a point beyond which the conservation needs of the building are seen as compromised. In such situations, the use of a fire engineered approach can offer an effective compromise through the use of active fire protection measures which can compensate for deficiencies in passive measures. It may be possible, for example, to compensate for deficiency in escape route travel distances and combustibility of materials by the use of automatic fire detection and suppression systems to provide early warning to occupants of the outbreak of fire and inhibiting of the fire growth, increasing time for safe escape.
Proposed additional guidance clause - 2.15.7 Conversion of traditional buildings to hotel use
When considering suppression as part of a risk based alternative approach (refer to clause 2.0.7) reference should also be made to Historic Environment Scotland Guide for Practitioners 6 “Conversion of Traditional Buildings; Application of Building Standards” and other relevant Historic Environment Scotland documents citied within this guidance.
