Issue 42 summer 24 web - Flipbook - Page 34
exacerbated by more frequent extreme weather events in
recent years which have further accelerated deterioration
to the historic building, and the lantern in particular.
avoid chasing into the timber and drawing moisture in.
From this point, around the bases of the columns, through
the gutter all the way to the outer edge of the stone coping, the existing and new lead was overlaid with a liquid
PMMA lining with fibreglass reinforcement. This formed
a continuous layer that covered over the multiple joints
to the lead which had previously and continued to prove
vulnerable to capillary action from a combination of
rainwater and high wind from all directions.
Paradoxically, although the main part of the Tower is solidly
constructed in stone, the highest part, the Lantern, is
constructed in timber beneath a cast iron roof (the fluted
cast iron columns around the Lantern are non-structural).
The external walls of the Lantern are formed by nothing
more substantial than timber panels. This construction, and
its associated traditional lead details, has failed repeatedly
throughout the building’s history.
Further necessary steps which emerged on site involved
sealing up joints and lead dressings to the perimeter cast
iron columns of the lantern, and fitting an additional pane
of glass behind the ‘X-frames’ above the panels to avoid
water tracking into the gap that formerly existed there.
At the start of this project, the principal defect was the
water ingress at the timber-panelled lantern at the top of
the Tower, which had rotted the base of the southwest
timber panels and posts. Rainwater had also found its way
through the high-level gutter and slightly lower sumps,
the latter of which had damaged decorative plasterwork
in the Belvedere.
These steps represented a move away from like-for-like
traditional detailing, necessary for this particular situation.
Repairs of that nature had been executed as part of a previous project 25 years ago, but had quickly been found to
be unsuitable. The materials available to us at present
have found a compromise between the appearance and
composition of the original detailing, and adequate
weatherproofing achieved through careful layering,
dressing and finishing of the various elements.
The last restoration in the 1990’s was well documented.
Traditional detailing had been used, and had been executed to the highest standards, but had still failed due to
the high exposure to the weather, and the vulnerability of
the historic detail and the existing materials to this. It was
agreed that for this project a different approach was
needed in order to preserve the structural integrity of the
Lantern and the significant interiors. The principal steps
were to replace the decayed panels, and posts in accoya,
a modified durable timber, which is highly resistant to rot.
Stonework
Further down the building, a series of stonework repairs
were carried out to address, in part, issues with previous
repairs, but also to fragile sections of stone which had been
subject to weathering and in places were compromising
the discharge of rainwater. This encompassed a range of
techniques, including de-frassing friable stone and the application of a nanolime liquid consolidant, often chosen
The lead flashings to the timber panels and posts were
re-formed and re-dressed behind a termination bar, to
Below, Beckfords Tower grotto, photograph by Casper Farrell
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