ounded in 1935, Marr College in Troon, Scotland, is one such example. Category B listed, the secondary school is of special historic interest, both due to its architectural style and because it was created with the financial backing of local coal merchant, Charles Kerr Marr. Serving the local community for more than 80 years, an overhaul and expansion was recently required to allow for increased accommodation.
But as the building has listed status, any expansion would need to be carefully considered, allowing the building to become more suited to modern demands without losing its heritage. As part of this, meeting the necessary safety requirements of today’s building regulations was crucial – something which could be achieved by specifying materials appropriately.
With increased numbers of students now attending Marr College, achieving improved building circulation was a critical part of the development. This involved a change of use of two existing courtyard spaces to create large multi-use atria, made possible with the installation of an Ethylene Tetrafluoroethylene (ETFE) roof. Alongside creating larger and more practical spaces, ensuring effective fire protection without detracting from the courtyards’ architectural features was critical.
That’s where Pyroguard came in. Working closely with steel fabrication specialists, Martec Engineering – who provided the steelwork within the courtyards, including Schueco Jansen fire-rated glazed screens – Pyroguard supplied a variety of fire-rated glass solutions to sit within the new screens.
Due to the ambitious nature of the project, more than 300m² of Pyroguard toughened glass, including Pyroguard Integrity Plus T EW30/6, Pyroguard Rapide Plus EI30/EI60 and Pyroguard Protect T-EI60, was chosen for its unrivalled quality and safety features. Protecting against flames, smoke and radiant heat, the selected glazing range has the advantage of providing Marr College with additional radiant heat control and greater fire protection.
In tests, this glass demonstrates the ability to maintain the amount of radiant heat to below 15 kW/m² on the unexposed face, protecting critical evaluation routes for occupants.
The result of this collaboration was the creation of a space which is light, airy and elegant, providing all safety protections in the event of a fire without impacting on the architectural language of the original building.
Rising to the challenge of fresco restoration
The Painted Hall at the Royal Naval College at Greenwich is one of the jewels in the crown of the UK’s naval heritage.
Billing Jones from Scaffolding Specialist, Millcroft
For the past 50 years, the 7000m² of frescos across the walls and ceilings of the Grade 1 Listed building (and Scheduled Ancient Monument) have remained untouched by restorers until a Heritage Lottery-funded conservation project to clean the precious paintings and continue their preservation for future generations.
Scaffolding specialist, Millcroft, designed, built and managed a bespoke scaffolding solution to allow the restoration team to carry out the painstaking work safely while protecting the building and providing access for public tours of the restoration.
The project was carried out in two core phases; work on the dome-roofed Vestibule took place first, followed by the main Painted Hall area. Millcroft designed the scaffolding for the whole project and erected the Vestibule scaffolding first so that work could commence in this area and continue here during the five-month programme to erect the scaffolding in the Painted Hall.
The scaffolding had to be erected within restricted loading requirements to avoid any structural damage to the building or stress on the floor finishes
It was modelled in 3D and its weight was dramatically reduced by the use of aluminium tube rather than steel. Using profiled metal, rather than traditional wooden scaffold, also reduced both weight of the system and the fire risk. Supporting access towers were installed to spread the weight load evenly across the floor and high specification vinyl was used to protect the tiled floor from compression damage or puncturing.
For the public access routes, a bespoke access lift was commissioned and two public access-rated staircases were constructed, with a ply layer laid onto the metal deck for the public access routes and viewing gallery to maintain a consumer-facing finish.
While conservation officers and others are keen to ensure the use of traditional lime-based plasters and renders, research into new technology suggests that better, more effective options are available. Hudson Lambert, Director of Safeguard Europe, considers the alternatives.
Hudson Lambert is Director of Safeguard Europe
The preference for lime plasters in conservation applications today is because of their perceived breathability – allowing walls to attenuate moisture to the environment – yet in the face of rising or penetrating damp, lime plasters can start to fail. This is especially the case where the dampness introduces salts into the plasterwork.
Consequently, there is a need for internal plastering systems that are impervious to damp; while not creating the problems associated with a sand and cement system: condensation risk and vapour impermeability.
New ‘second generation’ plastering systems have been introduced that are more resilient to dampness and salts than traditional plastering methods. These modern systems are capable of being applied to walls that are still damp and can resist high levels of moisture and salt ingress. The make-up of these plasters means they have large pores and a high pore volume. This allows salts to form within the plaster rather than on the surface; and the high pore volume results in thermal resistance, reducing the risk of condensation.
Other properties include a 0.3m² compressive strength, ensuring that the plaster can easily be removed later without damaging underlying brickwork; high water vapour diffusion (breathability) and conformity for the EN998-1 CE Standard as ‘Renovation Mortars’.
Furthermore, new research shows that lime plasters are far from the most breathable of their kind; and modern hybrid ‘hi-lime’ or damp-resistant materials are far more effective. In these tests, hi-lime plasters were shown to allow transmission of around 1.2kg/m² of water vapour over a 14-day period, compared to 0.85 1.2kg/m² for a traditional mix of 3:1 sand and lime. More interestingly, recently introduced proprietary damp-resistant and fast set plasters were shown, over two weeks, to transmit 1.55 and 1.48kg/m² of water vapour respectively.
The orthodoxy around plastering in listed and conservation environments – save when special materials or skills, such as horsehair or pargeting, are demanded – can now be effectively challenged: and in the best interest of heritage buildings too.