Issue 41 Spring web - Flipbook - Page 34
Slowing down the
decline of ruins with
skilled conservation work
Cliveden Conservation’s Stonemason, Amelia Morrison, discusses the sensitive conservation of ruins
and the various challenges it presents, from the removal of vegetation and cementitious hard capping to
the application of lime mortar in all weather.
Sensitive conservation is crucial to preserve the complex
structure of ruins. There is a considerable amount of
subtlety when it comes to specifying, and a reactive
approach is necessary to protect the remains. When
working with ruins, it must be accepted that permanent
solutions are not necessarily realistic; our aim is not to
freeze the structure in its current state but to slow the
decline as much as possible using an approach that can
be distilled into three priorities: evaluate the effects of
historical interventions and remove only what is essential
for the preservation of the site, wherever possible, retain
all features of historic significance, however small or seemingly insignificant, and only add that material which is
necessary to slow the decline of the ruin.
Cementitious hard capping can be problematic
The use of cementitious hard capping is often the most
common and damaging of all historic interventions.
Moisture can be trapped behind it, causing the historic
mortars and stone to decay more rapidly, and cracks and
fissures on the surface can allow vegetation to take hold.
Cementitious hard capping can also overburden the lower
portions of the walls.
Although removing cementitious hard capping may seem
like the best solution, the conservation team must
consider whether it is causing further damage and the impact of removing it. For example, will it cause additional
damage and losses? At Ankerwycke Priory, a 12th-century
chalk rubble ruin near Runnymede, it was necessary to
remove approximately 500mm of material across the
entire wall head; the weight of the cementitious hard
capping was crippling the lower sections of wall, allowing
vegetation to take hold where it was failing, and creating
a differential erosion zone where it met the historic
mortars below. Cementitious repointing was also causing
significant recession to the chalk faces.
In contrast, King John’s Castle in Odiham (built c.1207)
is comparatively stable despite the presence of cementitious mortars right across the higher elevations. This may
partly be due to the high proportion of flint in the rubble
walls, which is far more robust and can stand up against
harder mortars more readily than softer stones. It would
be detrimental to remove cementitious mortar which is
not failing, and on such a vast scale that it would seriously
alter the profile of the ruin.
Below, hot mixed lime mortar being used to consolidate the chalk ruins at Ankerwycke Priory