ST. JOHN'S, March 15, 2016 /CNW/ - Historic Plaster Conservation
Services Limited (HPCS) announced today that a plaster ceiling the
company consolidated in 2009 was accidentally flooded with water in
2015 and yet still easily passed a structural load test. The testing
revealed the water had no negative effect on the structural integrity
of the plaster. The consolidation treatment process protected the
ceiling from what may have otherwise been a great loss.
The 1850 Colonial Building is a Provincial Historic Site that is to be
recommissioned as a museum of Newfoundland's political history, and has
been undergoing an ambitious restoration project coordinated by Stantec
Architecture. The landmark building is the most significant in the
province and is renowned for its intricately finished interior,
particularly the ceilings of the Council Chamber and Assembly Room.
In 2009, HPCS was commissioned by the Newfoundland Tourism, Culture and
Recreation Department to preserve the ceilings in these two grand rooms
with a treatment method called 'plaster consolidation.' The method
involves the application of a polymeric binder (acrylic emulsion) to
the reverse side of the plaster. The binder adheres the plaster to the
wood lath substrate and saturates the plaster system, which is greatly
strengthened. This treatment method was chosen because it could be
applied from the reverse side of the ceiling without disturbing the
important historic finishes in the rooms. HPCS and Stantec
Architecture were joint recipients of an award from the Canadian
Association of Heritage Professionals for the successful project.
In 2015, a number of very observable stains began to appear on the
ceilings of both the Council Chamber and Assembly Room. HPCS was
summoned to conduct an inspection and confirmed that the ceilings had
been flooded with water. The stains were caused by water carrying dirt
and soot from the attic through existing cracks in the plaster.
"We've been consolidating plaster ceilings since 1983," said Eric
Stewart, president of HPCS, based in Port Hope, Ontario. "But we've
never encountered a flood like this on a ceiling we had already
treated. This is the first time we've been asked to reassess
consolidated plaster. We couldn't determine how strong or intact the
ceiling was in our traditional way. So we recommended an engineered
'pull test' to determine if the water had compromised the strength of
The protocol for the test was developed in the United States by Dean
Koga (Building Conservation Associates) and Ken Follett (Quality
Restoration Works) who have experience in testing consolidated plaster
ceilings. They developed a controlled method for quantifying the
load-bearing capacity of ceilings of this construction.
At the outset, the decision was made to conduct the pull test on the
Council Chamber ceiling because it had suffered the most water
infiltration. It was determined that a safe load-bearing capacity for
this particular type of ceiling plaster is approximately 30 pounds per
square foot, which equates to the weight of the plaster plus a safety
factor of five.
The pull-test revealed that the plaster could withstand 128 pounds per
square foot before failure. The failure occurred within the plaster
matrix itself but there was no failure of the bond between the plaster
and wood lath. It was therefore concluded that the consolidated
plaster, even after experiencing water infiltration, could support the
weight of the plaster, plus a safety factor of at least 25 times.
"I was surprised and really happy with the results," said Stewart. "The
test provided us with some very positive information. First, our
method of consolidation appears to improve the plaster's resistance to
water. And second, in this case the treated plaster's structural
integrity was not diminished by infiltration of water. We are very
happy the province chose to consolidate the ceilings when they did
because we're pretty sure this would have been a much different story
Historic Plaster Conservation Services (HPCS) pursues opportunities in
the very specific field of architectural plaster conservation. The
company addresses and repairs the structural problems of fragile
plaster in historic buildings. Over the years, it has developed and
patented an array of specialty products, techniques and tools, designed
to strengthen and re-attach existing plaster on ceilings and walls.
HPCS pioneered plaster consolidation in the 1980s and has since
successfully consolidated ceilings in more than 100 historic buildings
in the United States and Canada. The company's headquarters are in Port
Hope, Ontario, and North Arlington, New Jersey.
SOURCE Historic Plaster Conservation Services Limited
Image with caption: "Plaster Conservation Services Limited Logo (CNW Group/Historic Plaster Conservation Services Limited)". Image available at: http://photos.newswire.ca/images/download/20160315_C9039_PHOTO_EN_44692.jpg
For further information:
Eric Stewart, (613) 889-1794, firstname.lastname@example.org, www.historicplaster.com