Fire Control Measures at Lanhydrock

Paul Holden

 

Timber-panelled drawing room with period furnishings, decorative plaster ceiling and partially glazed door  
Lanhydrock’s spectacular Drawing Room: a pragmatic solution in the form of a simple risk assessment was implemented to prevent damage to this 19th-century highly carved door with etched glass  

Lanhydrock House is a Grade I listed mansion situated on the edge of Bodmin Moor in Cornwall. Since 1621 it has been home to successive generations of the Robartes family. After a major fire in 1881 the house underwent a four-year refurbishment programme before becoming a family home again. Serious attention was paid to fire risk in the early 1990s when an advanced automatic fire alarm system was installed alongside a series of fire doors which extended physical vertical compartmentation to the ground and first floor service corridors and, in the process, created two new protected staircases for means of escape.

In 2005, 60 years after the National Trust took ownership, the Regulatory Reform (Fire Safety) Order was passed. In response the National Trust commissioned a detailed risk assessment from which a two-year phased schedule of works was instigated to develop the property’s passive and active fire safety strategies. The project posed many challenges, not least in effecting statutory change without any visible impact on the building and its outstanding interiors.

PASSIVE MEASURES

When planning a historic building’s passive fire safety strategy, it is essential to first evaluate the property’s historic layout and construction to minimise damage to the fabric and reduce overall costs. Like most buildings, Lanhydrock benefits from natural lines of compartmentation – a consequence of the historic floor plan. Furthermore, the post-fire refurbishment was specifically carried out with fire safety in mind. The Victorian iron fabricated structure significantly reduced the amount of timber beneath floors and throughout the roof voids, while 12"-thick concrete ceilings then, as now, offer sound fire resistance between floors. If they are carefully monitored and maintained these historic features will still provide 60 minutes fire separation. However, if they are compromised, the building’s ability to withstand fire spread will be seriously undermined.

One such weakness was discovered beneath the ground floor in the brick vaulted tunnels (now a service duct) which connect the boiler room with the historic interiors. The risk assessment identified the high potential for fire spread from the boiler room into the tunnels and thence vertically and horizontally into the mansion. One option was to install fire shutters or curtains throughout the tunnel, corresponding with vertical compartment lines above. However, this intervention would have restricted easy access through the tunnels and compromised an important bat roost. A more practical solution was to seal the many pipework and cabling breaches in the roof and sides of the tunnels with proprietary sealing systems and to add a fire door and shutter at each entry point, thereby creating a single horizontal compartment.

B/w photo of Lanhydrock facade and ornamental gardens in 1881 Colour photo showing the largely unaltered facade at the time of writing
Left: Lanhydrock in 1881, soon after a major fire and right: Lanhydrock today (Photo: NTPL/Lee Searle)

Maintaining the integrity of masonry walls is vital in order to inhibit the spread of fire, heat and smoke. However, Lanhydrock’s fire risk assessment identified the need to examine, repair and upgrade all elements of each vertical compartment. For example, historic panelled doors were upgraded with leaf edge perimeter seals and intumescent hinge papers and varnishes. To reduce the risk of unseen fire spread through the door frame itself, all cavities were sealed behind architraves and beneath floors with masonry, intumescent sponges and sealants in order to achieve a fire-resistance duration comparable with the walls. Before work was carried out careful thought was given to the disturbance of the historic fabric and how modern interventions can compromise the operation of the property. One example that had to be overcome was the potential risk in blocking or hindering natural ventilation systems beneath floors that would in turn compromise the ability to maintain a constant relative humidity throughout the property for collections care. By sealing necessary gaps beneath floors and installing intumescent air vents, air flow was maintained until activated by heat. (Heat causes the intumescent material in the vent to expand forcefully, blocking the potential fire path.)

Partly because the use of the mansion had changed since the 1990s, the risk assessment identified the need to create three new vertical compartments, one to separate the internationally important 17th-century gallery (and the shop area below) from the rest of the house, and the other two to create further protected staircases for means of escape. To facilitate this upgrade, three new bespoke fire doors, based on Victorian patterns, were introduced into the historic interior and two historic lift shafts that breached all levels of the property were treated as distinct compartments and upgraded to suit.

In consequence, Lanhydrock now has nine vertical compartments which, added to the Victorian concrete vaulted ceilings, create around 30 fire-resistant boxes across 100 rooms and three floors. The objective was to ensure that these compartments would offer a minimum of 60 minutes protection. All of the interventions described above have been certificated by an approved contractor to show that intumescent products have been installed in accordance with the manufacturer’s instructions.

ACTIVE MEASURES

  Timber fire door designed to replicate the original
  One of three new fire doors installed into the property: the doors won an award for their design and manufacture.

A necessary part of the project was to replace the old unsupported fire alarm system. As part of the specification, prior to installation all existing fire-graded cabling was tested for continuity and certificated and all new cable runs, where required, were installed in mineral-insulated cables which have a higher fire integrity and longer life span than PVC cabling. Careful thought was given to pipework and cable runs in order to minimise further damage to the property.

During the design phase it was decided that any new fire alarm system must include a fully monitored intelligent fire panel. Hence, each of the 350 smoke (or heat) sensors, five VESDA units (very early smoke detection apparatus) and manual call points are coded with a unique address which on fault activation will provide a text message on the panel and, for remote users, a localised pager call via a radio link. Furthermore the panel interfaces with electromagnetic door-release systems, gas leakage alarms, fusible links on gas fired boilers, a self-setting fire curtain separating high risk areas from historic interiors and remote signalling to the monitoring station.

One element of the Regulatory Reform (Fire Safety) Order that has a daily impact on the running of the house is the duty to remain accountable for the upkeep and maintenance of these systems. Annual reviews of the fire risk assessments must be carried out and meticulous records kept of fire alarm and emergency lighting testing, evacuation exercises and fire safety training. Annual testing and certification must also be carried out for fire-fighting water supplies, back-up battery packs, gas boilers, gas supply pipework, extinguishers, chimneys that host open fires or extraction systems and electrical installations.

STATUTORY PROTECTION AND CURATORSHIP

Modern interventions in historic building fabric always raise difficult questions. The answers can be found by applying sound conservation principles and by understanding how the heritage asset functions and performs. Indeed, the success or failure of a project can depend on very basic decisions such as the careful assessment of the longevity, performance and aesthetic appearance of intumescent products before they are installed or applied.

A greater challenge is the curatorial duty not to destroy or damage the very heritage that we are trying to protect. Our aspiration to protect Lanhydrock through applying pragmatic and effective solutions was displayed by our refusal to upgrade a handsome 19th-century drawing room door (with integral Aesthetic Movement glass) to create a protected escape route. Rather than apply fire-rated secondary glazing, intumescent varnish on the glass or a fire shutter/curtain above the door, we came to a more sensible resolution which was to consider the volume of the room in terms of the amount of smoke likely to be generated by its fabric and contents in the period required to evacuate the building safely, and the ability to contain this volume of smoke within its barrel-vaulted ceiling. This simple risk assessment saved money, time and, more importantly, unnecessary damage to the historic interiors.

Firefighters use an extendable ladder as part of a fire drill at Lanhydrock  
One of the regular fire exercises that take place at Lanhydrock: close links with Cornwall Fire and Rescue Service have reaped many benefits including the creation of a detailed fire salvage plan.  

Another potentially sensitive intrusion on an historic interior is the installation of emergency lighting, fire signage and self-closing fire doors to protect the means of escape. One way to avoid unsightly or temporary escape lighting is to convert the main historic lights to double-up as emergency lighting. This can be done by fitting battery packs connected to inverter switches. The inverter component produces 230v AC from a 12v DC back-up battery, while the switch component automatically switches power supplies to the battery in the event of a mains power failure.

Excessive signage and self-closing devices can be avoided through well managed and practiced evacuation procedures where visitors are chaperoned from the building to outdoor muster points by trained volunteers while fire doors are manually closed en route. Solutions like these will retain the authenticity, appearance and value of the heritage asset.

Another curatorial duty is to produce, manage and regularly test damage-limitation measures (Holden, 2010) and emergency plans (Holden, 2004). Museum professionals should seek to reduce fire risk at every opportunity through regular review of procedures, systems and training. In the event of fire their role is to facilitate the progress of the incident by advising the emergency services on aspects as diverse as room layout, systems infrastructures, priority salvage, storage and care of retrieved items, and afterwards deal with site security and inventory checking.

A key factor of emergency response is working closely with the fire service. Familiarisation with property, chattels and property teams can only be a good thing. Support from local crews will allow rehearsal and familiarisation towards the emergency procedure plan. Likewise, the infrastructure to support fire and rescue systems must be assessed, for example the installation of deep hard-standings in our courtyard to accommodate specialist high-level cranes, rehearsing tunnel rescue and rope techniques and drawing back-up water supplies from external sources. Regular visits from each duty watch have kept plans fresh and well rehearsed.

THE BOTTOM LINE

The success of any project relies on the co-operation of conservation, heritage and fire specialists, in our case the National Trust building team with support from ASG Security, Simon Brewer Carpentry, Chubb Fire and Security, Cornwall Council, Cornwall Fire and Rescue Service, English Heritage, International Passive Fire Ltd, and Pearn and Proctor Architects.

  A member of the NT direct labour team seals pipework and cabling breaches in a brick-lined tunnel
  Sealing all breaches between the tunnels and the ground floor created a single horizontal fire compartment. All work was carried out by the National Trust’s own direct labour team.

In responding to the fire risk assessment we have made well-informed decisions that were based on good practice and sound research. At the outset it was decided that the project team should maintain meticulous records of the works in order to be accountable for the changes we, as custodians, were making to our heritage. The result is a comprehensive ‘as built’ documents record, both in textual and photographic form, showing the ‘before’ and ‘after’ stages of the project and clearly demonstrating the logic that we have applied in implementing change.

We are working on phase 3 of the project, which may include changing our natural gas fired boilers and giving our storage water reservoir a structural inspection.

As with all efforts to manage fire risk, the effectiveness of any solution will rely on the amount of care that is put into its preparation. The tasks of trying to predict how fires might start and spread in large historic properties and of designing suitable countermeasures are fraught with difficulty – seemingly endless possibilities and permutations must be taken into account. It is, perhaps, an unusual kind of work that demands so much effort but which all involved hope never to see in action.

~~~

Recommended Reading

P Holden, ‘Heaven Helps Those Who Help Themselves: The Realities of Disaster Planning’, Journal of the Society of Archivists, Vol 25, No 1, 2004

P Holden, ‘Damage Limitation, Planning and Training at Lanhydrock House, Cornwall’ in S Kidd, Fire Safety Management in Traditional Buildings, Part 2, Annex II, Historic Scotland, Edinburgh, 2010

 

 

The Building Conservation Directory, 2014

Author

PAUL HOLDEN MA FSA is house and collections manager for the National Trust at Lanhydrock. Formerly a heating engineer and lead tradesman at Winchester College, he has been at Lanhydrock for 14 years during which time he has overseen many significant projects including, between 2011 and 2013, the implementation of works arising from the fire risk assessment. He is also an architectural historian and the author of two books and numerous scholarly articles.

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