Conservation works are underway on the roof of King Charles Court. We got to take a look behind the scenes, and discover how traditional building methods survive to this day.

The King Charles roof – the new lead valley gutters in place with the pitched roofs above in varying stages of covering

With the restoration of the monarchy in 1660, Charles II enjoyed a popularity that enabled him to spend lavishly on grandiose palaces for his personal enjoyment. The King Charles Court at the Old Royal Naval College is the only realised wing of one such palatial fantasy, predating Sir Christopher Wren’s twin domes and the Painted Hall (you can learn more about the history of the site here). These conservation works are located to the west range of the King Charles building, which dates from 1812-1815, following the replacement of Sir Christopher Wren’s previous smaller west range by John Yenn.

The King Charles Court is now undergoing a £300,000 conservation project to repair the roof, involving the replacement of roof slates, renewal of valley gutters and stonework repairs.

What is fascinating about the project is the employment of traditional techniques to ensure the conservation of the building for years to come.

Removing the lead exposed significant deterioration of the roof beneath

The previous roof defects related to the incorrect detailing of the valley gutters as well as the use of modern materials and underlays beneath the lead. The above photograph shows both water damage to the plywood deck and a white powder (lead carbonate) caused by the corrosion of the underside of the lead due to condensation.

To prevent condensation to the newly installed lead ventilation to the roof space has been increased and more traditional construction methods utilised.

Traditional sand cast lead has been chosen in preference to modern rolled lead sheet. The use of sand cast lead dates back to the Romans and involves the pouring of molten lead across a prepared sand bed which provides a rough texture on one side. The use of sand cast lead is a requirement of the ORNC’s Scheduled Ancient Monument designation and also provides an improved aesthetic over milled lead.

As the ORNC also has a blanket no “hot works” policy traditional bossing techniques have been employed to dress the malleable lead into shape, rather than resorting to modern methods of cutting and welding the lead sheet. This is both a more traditional and skilled method of leadworking and removes any risk of fire to the building.

The 30-year-old Spanish slate tiles (left) are dwarfed by the original, and longer-lasting, Welsh slates (right).

The existing slates, thought to be Spanish and installed within the last 20 years, will be re-used where sound. Any new slates will be of high quality Welsh slate to ensure the roofs longevity.

Only one small section of the original roof slates remain and will be retained. These slates were originally laid in diminishing courses (with larger slates at the bottom of the roof) and are significantly larger than modern slates.

A rusted cramp and the chunk of stone it caused to fall out

A common problem encountered at the ORNC is damage to stone work caused by rusting metal cramps (originally built into the masonry to secure adjacent stones in place). Working on the roof has allowed DBR’s skilled masons to remove rusted cramps within the masonry. The expansion associated with rusting cramps creates pressure within the stone and results in pieces of stone spalling off.

In addition to cramp damage, general repointing of the fine stonework joints is being undertaken. Due to narrow nature of these joints they must be chased out by hand to avoid damage to the surrounding stonework.

2016 is to be a year of major conservation work, culminating in the conservation of the Painted Hall. Click here to learn and read news about the ambitious project.

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