In the Footsteps of AR Powys
An unusual timber conservation case study
||The east end of St Andrew’s, Winterborne Tomson: the oak barrel-vaulted ceiling probably dates from
the 15th or early 16th century, while the box pews, screen, pulpit and altar rail are early 18th century.
The Church of St Andrew, in
Winterborne Tomson, Dorset, is a
small Norman church, unaltered in its
plan since the early 12th century. It still retains
the original single cell form with its curved
(apsidal) end. The oak barrel-vaulted roof
probably dates from the late 15th or early 16th
century and is believed to be unique in that it
spans the curve of the apse. All of the interior
timberwork, including the box pews, screen,
pulpit and altar rails, is early 18th century. The
gallery is also of this date but incorporates
parts of the medieval screen and rood loft.
By the early 20th century St Andrew’s had
fallen into a very poor state of repair, and when
the architect AR Powys rescued the church
in the 1920s it was almost derelict. Powys was
by then the secretary of the Society for the
Protection of Ancient Buildings, and a pioneer
of conservation. Founded by William Morris
40 years earlier, the SPAB was born out of
a reaction to the insensitive ‘restoration’ of
churches in the pursuit of an idealised vision
of the past. Here Powys sought to preserve as
much of the surviving fabric as possible and he
carried out a remarkably sensitive programme
of repairs, conserving original material that
would, at that time, usually have been discarded.
He and his wife are buried in the churchyard.
A plaque in the church, beautifully cut by
Reynolds Stone, commemorates Powys’ work.
A programme of conservation at
St Andrew’s was recently funded by The
Churches Conservation Trust, which has
cared for the church since 1974. The aim was
to preserve the interior decorative timberwork
which was suffering from an ongoing infestation
of deathwatch beetle. The project brief included
the consolidation and conservation of the
moulded wall plate (the horizontal length of
timber on which roof timbers rest), the roof
bosses on the barrel-vaulted ceiling and the west
gallery front, as well as the repair of the west
door. Given the scope and complexity of the
work, this article focuses on the conservation
of its eight finely carved roof bosses.
As with all conservation projects, the first
step was to examine and record the areas to
be dealt with alongside an overall appraisal of
the church. The extreme fragility of the wall plate and bosses was immediately evident
and several other issues were highlighted
that posed difficult questions and generated
intense debate. Much of this centred on the
repairs that the decorative timber elements
had undergone over the years: which repairs
needed replacing and which should be retained?
What justification was there for removing
repairs that were functioning but unsightly?
And, most unusually of all: should some of
the repairs that were no longer functioning
be retained on the grounds that they were
revolutionary for their time and therefore
historically significant in their own right?
|Conserved bosses over the apse
Amazingly, Powys had managed to retain
fabric that was so riddled with deathwatch
beetle holes that little or no structural
integrity remained. The bosses had all been
removed, filled with large quantities of wax
(probably bees wax), screwed to timber
mounting boards with protruding tabs and
then screwed back into position on the ceiling
ribs. Additional timbers had been nailed to
some of the backboards to offer additional
support. These hinted at the original form of
These repairs and others, such as
the timber supports for the gallery panels,
were visible and ‘honest’, in the spirit of
the SPAB’s philosophy, easily differentiated
from the original fabric. However, in many
places they were very crude and in several
instances the additional timbers supporting
the bosses detracted from their original lines.
Several phases of repair had
taken place since Powys’ astonishing
interventions, and these too had a
bearing on the programme of works:
- A new beam had been incorporated behind
the moulded wall plate so the current
repairs to the wall plate did not need to
provide structural support other than to the
immediate surrounding area.
- A filler had been applied to the deteriorated
exposed face of the wall plate which had
discoloured to a vivid orange. This was
not only unsightly, but more significantly
prevented localised consolidation behind
the face. However, it was not deemed to be
damaging in itself despite providing little or
- Attempts at treatment of the deathwatch
beetle had resulted in an ugly rash of
black plastic injection nodules across the
- The wall plate had been crudely repaired
with both soft and hardwood indents,
which corresponded poorly, if at all, to the
original profile of the moulding.
||Much of the timber was riddled with the flight
holes of deathwatch beetle, and some of the
bosses were so far gone that there were more
voids than timber. (Photo: Brian Ridout)
||One of the best preserved bosses after
conservation, showing four beakheads arranged
in a square. To save the fine carvings in the
1920s, AR Powys had consolidated the timber
using wax and mounted each boss on a board
before fixing it back into its original location.
The repairs carried out by AR Powys were
probably unprecedented in their approach
and arguably deserved as much care and
respect as the building’s earlier historic
fabric. The conservation approach and the
specific methods used were shaped both
by the condition of the elements and by
the historical importance of his repairs.
The most challenging conservation
issue was how to consolidate the very friable
decorative timber elements, which had been
damaged by deathwatch beetle to such an
extent that in many areas more void than
timber remained. The wax which had been
applied to the face of the bosses in large
quantities, as a consolidant and filler, probably
as part of Powys’ original specification,
now offered little or no support to the
decaying timber behind, and in many areas
the deathwatch beetle had continued to eat
through the wax. The greatest difficulty was
gaining access to the underlying timber to
consolidate sufficiently to save the elements.
As it was obvious that the deathwatch
beetle infestation, present prior to Powys’
work, had continued, the first step was to
deal with the cause of the problems, then to
establish the severity of the damage and which
elements were structurally compromised.
DAMP AND DECAY
The principal source of damp penetration was
via flaws in the roof covering, and specifically
in a bituminous felt underlay introduced when
the roof was last re-laid. As this is not vapour
permeable, condensation which collects
on the underside cannot escape, making
the adjacent timber surfaces damp. Local
flaws were dealt with during the contract,
and the CCT hopes to relay the roof on a
vapour permeable membrane in 2010-11.
Treatment of the deathwatch beetle was
investigated and after extensive talks with damp
and timber decay consultant Brian Ridout,
of Ridout Associates, chemical treatment was ruled out. This type of treatment had
not succeeded in the past and there was no
reason to suspect that it would be successful
in the future. The most appropriate treatment
would be to install light traps in time for
the next mating season. Any remaining
deathwatch beetle population will continue
to decline and will eventually die out as
long as the church remains free of damp.
CONSERVING THE BOSSES
Consideration was given to further
consolidating the bosses with wax, in keeping
with Powys’ work, not least because this would
avoid the need for removing the applied wax.
As with all consolidation of highly friable
and absorbent materials, no consolidant
measure is truly reversible, and removing the
wax posed significant problems. However, it
was decided that further application of wax
could not penetrate the remaining timber
sufficiently to consolidate it without employing
a total immersion method, such as that used
with PEG (polyethylene glycol). This would
have altered the appearance to a greater
extent than other consolidation methods and would have been more costly. Furthermore,
the wax had been crudely applied; in many
instances it concealed the original carved face
of the boss and in all cases it disfigured the
carvings, making the original design difficult
to read. It had also attracted much dust and
debris. Trials were therefore proposed to
find a satisfactory compromise, including an
appropriate method for removing the wax
from the bosses, a suitable consolidant to
strengthen the friable timber, and appropriate
support fillers for the different areas.
|Boss from east end after wax removal and
consolidation. Support fill has been applied to protect
fragile areas, and the crude timber supports have
been reduced to follow the original profile of the boss.
|Central boss during conservation. Most of the
wax has been removed and friable areas consolidated.
A section of white Plastazote has been inserted for
support and to fill voids around the perimeter.
|Above: the interior of the church looking west and, right, the central boss in situ before conservation: the
wax conceals the friable state of the timber,
the back plate is visibly protruding behind the
boss, and one of the fixing tabs is damaged.
Wax removal: the most suitable method
was found to be mechanical, using scalpels
or small spatulas and fine surgical tools.
The timber was in such a fragile condition
that it was necessary to consolidate at
every stage of the removal process.
Timber consolidation: Paraloid B72 acrylic
resin in acetone applied in varying strengths
was found to be the most suitable consolidant
for the timber generally. Paraloid B72 in acetone
was used to re-adhere dislodged fragments.
Surface support fillers: it was necessary
to design several different fillers, and their
strength had to be then adjusted as required by
controlling the ratio of bulking agent according
to the condition of the adjacent timber to which
it was being applied. For superficial crevices
either Plextol B500 acrylic resin or Paraloid
B72 in acetone were used, both mixed with
spruce wood flour, polyfilla and pigments.
Void fillers: for the larger crevices between
the bosses and back boards Plastazote LD45, a
closed-cell cross-linked polyethylene foam, was
chosen. Clearly non-traditional and therefore
a controversial choice, its use provoked
considerable debate. It was selected because it
is lightweight, chemically inert, easily blended
in, and flexible so that it does not apply new
stresses to the surrounding fabric. Importantly,
it can easily be removed in the future as it was
attached to the backboard and not the bosses.
The first boss on the north elevation was
in the weakest condition. It predominantly
consisted of dust and frass (the powdery
waste produced by wood-boring insects). The
decision was made not to remove the frass
but to consolidate immediately, in situ, with
Paraloid B72, with the frass inadvertently
serving as a bulking agent. No attempt was
made to remove any wax in situ, as there
was no remaining structural integrity in the
timber. The boss was supported while the
three screws were gradually loosened and the
boss could be safely lifted down and placed
in a box to be transported to the workshop.
The remaining seven bosses were removed
from the ribs in the same manner and placed
face up in boxes on their backboards. They were
then transported to the workshop where the
wax was carefully removed by hand as described
above. The bosses were consolidated continually during this process with Paraloid B72. After
consolidation from the face, all the bosses were
turned to allow access to the sides and rear.
They were supported in boxes of dry sand with
a separating membrane and consolidant was
carefully applied to the rear by injection. Much
of the rear side of the bosses had disintegrated
entirely leaving a large void between the back
board and remaining original carved face.
The applied sections of timber were
removed or reduced with sharp chisels where
required, to either allow access to the rear
of the bosses, or to enable the bosses to be
read as originally intended. Filler was applied
to support fragile areas but no attempt
was made to restore the original profile.
Next, the Plastazote LD45 foam filler was
cut to shape and inserted around the perimeter
gaps to give additional lightweight support to
the fragile and vulnerable edges, to improve the
visual integrity of the bosses, and to avoid dust
and dirt entering. It was set back slightly from
the edge and adhered to the backboard with
Paraloid B72. A neutral colour was applied to
the Plastazote with pigments in Paraloid B72.
The backboards were then lightly cleaned
to remove accumulated dirt and debris and any
necessary repairs to the backboards and their fixing tabs were carried out. Original fixings and
iron nails were retained and pencil markings
from previous interventions were not disturbed.
Timber inserts from past phases of work were
only removed or reduced in size where this was
deemed necessary for access or visual integrity.
The largest of the bosses situated at the
apex of the ceiling was conserved using the
same methods as for the others. However,
when the wax was removed, crude timber
inserts were exposed. These were removed
on the grounds that they protruded above the
original line of the carving, preventing effective
consolidation of the fragile central areas.
On completion, a very thin coat of
limewash was applied to the deteriorated faces
of the bosses to improve their visual harmony.
This decision was based on the evidence of
early applications of a white limewash.
Following conservation of the wall
plate and ribs, the bosses were refixed using
stainless steel screws in the original fixing
holes. Where possible, the conservators
avoided packing holes with rawl plugs or
fibre plugs to avoid additional stress. The
bright steel was toned down by sandpapering
the surface and applying a brown wash.
THE WALL PLATE, RIBS AND GALLERY
The wall plate and to a slightly lesser extent
the ribs had also suffered extensively from
deathwatch beetle attack. Many areas had lost
the carved face entirely leaving little more than
a mass of flight holes. Black plastic injection
nodules, relating to an earlier treatment of
the deathwatch beetle infestation, had been
inserted around the full length of the wall plate
at approximately 30cm intervals and were
also present in some of the lower sections of
the ribs. As these were both unsightly and
redundant they were carefully drilled out
avoiding further damage to the timber and
filled to blend in with surrounding timberwork.
|Sections of wall plate from the south elevation before and after conservation. The orange filler and black plastic injection nodules were removed but
all timber inserts were retained despite their crudeness. The conserved wall plate was lightly limewashed. In many respects the methods of conservation
highlighted the beetle holes and fragile state of the timber work but it was thought that this did not detract from the charm of the church.
The orange filler applied along the length
of the carved wall plate and gallery was not
considered to be damaging in itself, but it
prevented the consolidant reaching the depths
required. Consequently, the decision was
taken to remove it as far as possible without
causing further loss of original material. Trials
carried out suggested the following solutions:
Filler removal: Acetone applied by brush
or syringe softened the filler sufficiently to
allow manual removal using small spatulas
and scalpels. The injection of acetone behind
the filler enabled the filler to come away from
the decayed timber without further damage
or loss. Consolidation was required before,
during and after the removal process.
The filler was softened sufficiently by
the application by brush and injection of
acetone to allow gradual removal without
applying pressure to the delicate and
fragile timber. Consolidation of the timber
with Paraloid B72 was carried out during
and after the filler removal process.
Removal of the filler, as with the wax on
the bosses, revealed the stark extent of the
damage caused by the death watch beetle. The
decision was taken not to conceal this decay
again but to keep these areas exposed offering
support fills to weak and vulnerable areas
only. The visual contrast between the carved
surfaces and the decayed surfaces ironically
resulted in enhancing the original work.
Surface support fillers: Plextol B500
or Paraloid B72 as used on the bosses was
also used as the binder more generally, but
with different fillers, adjusted to control
strength and texture. For the door, spruce
wood flour and pigments were added.
For the deeper voids of the wall plate and
gallery, glass microspheres were used.
Void fillers: to fill the large voids between
the timbers of the wall plate and the gallery,
lime putty and chalk (chalk dust and nodules)
were mixed with the local Masters Pit sand
(supplied by Rose of Jericho) and goat hair.
Jute twine dipped in a lime putty slurry
was inserted as a packer for deep voids.
Support fillers were applied to vulnerable
areas of the wall plate and ribs, and horizontal
voids between elements were pointed with the
lime putty and chalk mortar mix. The timber
indents from earlier repairs and any exposed
decayed surfaces were then treated with a thin
application of limewash to match adjacent areas.
SOMETHING OLD, SOMETHING NEW
Throughout the programme of works at
St Andrew’s, both past and present conservation
approaches were discussed and debated. It
is not surprising to find that the range of
technology and materials available to the
conservator has increased significantly since
the work of Powys in the 1920s. However,
many of the proprietary products now on the
market for the consolidation of timber cannot
be regarded as tried and tested in the context
of historic building conservation. Ultimately, a
carefully considered balance of traditional and
new materials and techniques was required.
Perhaps more surprising is the change
in practical approach to the philosophy of
conservation which is evident here. The inserts
made by Powys were designed to be readily
distinguished from the original, but some of
these distracted from the lines of the original.
Modern practice is to make alterations that
are less harsh and more sympathetic to the
original. The result has clearly enhanced the
simple charm of this beautiful church and our
approach should offer plenty of food for thought
for future timber conservation projects.
Historic Churches, 2009
LYNNE HUMPHRIES MA (RCA) is an architectural
conservator with 18 years’ experience working
in England and overseas. In 2002 she established
Humphries & Jones, which specialises in the
conservation of sculpture, monuments and
architectural works of art. The client at the
church of St Andrew’s, Winterborne Tomson
was The Churches Conservation Trust and
the building surveyor was Philip Hughes.
For further information on The Churches
Conservation Trust see www.visitchurches.org.uk.
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