In my capacity as an historic
preservation contractor and consultant, I am often afforded the opportunity to
become involved in exciting and challenging projects. Recently, we were awarded the contract to
restore the clay tile roof turrets at the Longy School of Music’s Zabriskie
House. Now a part of Bard College, the
Zabriskie House is actually the historic Edwin H. Abbot House with a
sympathetically designed addition built in 1969-70. The deteriorated condition of the turrets, as
well as lead-coated copper gutter linings and masonry dormers, had attracted
the attention of the Cambridge Historic Commission and a commitment to the
proper restoration of these systems was struck between the CHC, building owner
and a private donor.
Before I can specify historically
appropriate treatments, I need to don my consultant’s cap and dig into the
history of a building to best understand its evolution. Developing the background story will
typically answer questions and fill in the blanks when examining traditional
building systems. An 1890 newspaper
clipping held by the CHC reports that “[t]he stately home of Mr. Abbot, with
its walled-in grounds, on the site of the old Arsenal, promises to be the most
costly private dwelling in the city.” An
examination of records held by the Massachusetts Historical Commission and from
the Library of Congress’ Historic American Building Survey reveal that the firm
of Longfellow, Alden and Harlow designed the Richardsonian Romanesque portion
of the building and that Norcross Brothers was the builder of record.
Alexander Wadsworth Longfellow, Jr.,
was the nephew of the famous poet and an important figure in the architectural
history of the United States. After graduating from Harvard in 1876,
he studied architecture at the Massachusetts Institute of Technology and the
École des Beaux-Arts in Paris, after which he worked as a senior draftsman in
Henry Hobson Richardson's office. After
Richardson's death in 1886, Longfellow partnered with Frank Ellis Alden and
Alfred Branch Harlow to found the firm of Longfellow, Alden & Harlow. With offices in Boston and Pittsburgh, the
firm designed many important buildings including the Carnegie Library of
Pittsburgh and the City Hall in Cambridge, Massachusetts.
Norcross Brothers Contractors and
Builders was a prominent nineteenth-century American construction company,
especially noted for their work, mostly in stone, for the architectural firms
of H.H. Richardson and McKim, Mead & White.
Following the death of Richardson, the brothers became the contractor
for many of McKim, Mead & White's projects. As had been the case with Richardson, much of
the value of the Norcross Brothers to architectural firms derived from Orlando
Norcross's engineering skill. Though largely self-taught, he had developed the
skills needed to solve the vast engineering problems brought to him by his
clients. For example, the size of the dome at the Rhode Island Capitol was
expanded very late in the design process, perhaps even after construction had
begun, so that it would be larger than the one just completed by Cass Gilbert
for the Minnesota Capitol.
The Edwin Abbot House is an interesting
interpretation of the Richardsonian Romanesque style. Whereas the great majority of such buildings
feature rusticated, pink Milford granite in an ashlar pattern, trimmed with
East Longmeadow brownstone, Longfellow created a unique spin for Mr.
Abbot. While trimmed with the
brownstone, the field of the walls features coursed Weymouth granite of
slightly varying heights. The motif of
orange, brown and golden hues of the stone is continued in the brick wall
surrounding the property. The roof is
covered in a flat, square orange-red clay tile.
This is typical of Richardsonian Romanesque buildings which are almost
exclusively roofed in clay tile, Monson black slate, Granville, New York, red
slate, or some combination thereof. It
should be noted that because their need for stone was outpacing the supply, Norcross
Brothers eventually acquired their own quarries in Connecticut, Maine,
Massachusetts, New York, and Georgia.
The roof framing system of steel and terra
cotta blocks is relatively rare but makes perfect sense when considered in context with what the latest flooring technologies of the era were.
A network of steel beams was bolted together to form the rafters, hips
and ridges of the frame. Across each was welded rows of double angle irons (or,
inverted T beams.) Within these
channels, in beds of Portland cement, was laid the terra cotta block. The tile were then fastened directly to the
blocks with steel nails. Because of the
ferrous nature of the fasteners, the normal passage of moisture vapor caused
the nails to rust and expand slightly, anchoring them securely in place. Whether this element of the design was
intentional or simply fortunate happenstance, the result made for a
What doesn’t last forever in
traditional roofing systems like slate and clay tile is the sheet metal
flashing assemblies. Over the years
there must have been numerous failures which lead to the decision to remove the
clay tile from the broad fields of the roof and replace them with red asphalt
shingles in the 1980’s. Confronted with
the dilemma of securing the new shingles to the terra cotta substrate, a decision
was made to sheath the roof with plywood.
Holes were punched through the blocks and toggles used to fasten it to
the roof. In one area where the asphalt
shingles were removed, more than 50% of the plywood exhibited varying degrees
of rot due to the normal passage of moisture vapor from the interior spaces.
Fortunately, the turrets had survived
the renovations from thirty years before.
A conical turret, in the rear, and an eight-sided hip-roofed turret on
the north sided required only repairs which, while extensive, did not require
addressing issues with the substrate.
The sixteen-sided turret, on the primary façade of the building, was in
poor condition. Over the years, “repairs” included the use of non-matching tiles, red roofing cement, tar,
caulk, and even red slate. A scaffold was
erected to allow safe, unfettered access to the entire turret and the process
of removing the tile began. Care was
taken to conserve as many tiles as possible for use in repairing the other two turrets.
The substrate was examined closely and,
save for thousands of tiny craters created by the original nails, found to be
sound. A new system for fastening the tiles had to be devised so that they could be attached to the terra cotta blocks. It was critical that the new method allow for the replacement
tiles to be securely fastened and resist the damaging forces of escaping
moisture vapor. Cement board, comprised
of 90% Portland cement and ground sand, was fastened to the blocks with
ceramic-coated masonry screws. The
entire turret was then covered with a self-adhering membrane. The replacement tiles were carefully matched
and sourced from a salvage dealer in Illinois and secured with stainless steel
fasteners. The flat tiles, no longer
manufactured new, are referred to as “Cambridge” tiles for their prevalence on
the roofs of great homes and institutional buildings in and around Cambridge,
While I typically advocate for the
retainage of all historic fabric when preserving and restoring traditional
building systems, there are exceptions.
In the case of the Abbot House roof, we encountered once-modern technologies which pointed us toward contemporary means and methods. Rusting steel nails in the terra cotta block
worked brilliantly for the initial installation but seemed ill-conceived for a second go
around. The use of non-ferrous fasteners
and a new substrate that is impervious to moisture infiltration will guarantee
the turret’s service life for the next 125 years or more.
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Do you care about historic buildings?
If you don’t understand how contemporary insulation
practices damage historic building fabric, please read “Is Greener Always
Better? Problematic Use of Modern
Materials in Traditional Building Systems” (http://www.preservationconsultant.net/blog/-is-greener-always-better-problematic-use-of-modern-materials-in-traditional-building-systems). According to the article referenced above:
“The changes, proposed by a team of industry representatives
from the New Buildings Institute (NBI),the Natural Resources Defense Council
(NRDC), and the Institute for Market Transformation strip the exemption
language from the code. The group added a requirement that project teams
file a report with a code official when seeking immunity on specific areas of
the design or construction.”
Who are these organizations that made this recommendation?
According to their website, the New Buildings Institute “is a nonprofit organization working to
improve the energy performance of commercial buildings. We work collaboratively
with commercial building market players—governments, utilities, energy
efficiency advocates and building professionals—to remove barriers to energy
efficiency, including promoting advanced design practices, improved
technologies, public policies and programs that improve energy efficiency. We
also develop and offer guidance to individuals and organizations on designing
and constructing energy-efficient buildings through our Advanced Buildings®
suite of tools and resources.”
I didn’t see anything that indicates an understanding of
traditional building systems so I checked out the Natural Resources Defense Council’s website. Still nothing about old buildings. They’re an environmental action group whose
mission statement is “to safeguard the Earth: its people, its plants and
animals and the natural systems on which all life depends.” Admirable, but where’s the expertise
determining what’s right or wrong with energy conservation relative to older
That left just the Institute
for Market Transformation … would they be the ones with demonstrable
knowledge and expertise relative to traditional building systems? According to the website, they’re “a
Washington, DC-based nonprofit organization promoting energy efficiency, green
building and environmental protection in the United States and abroad. IMT's
work addresses market failures that inhibit investment in energy efficiency and
sustainability in the building sector.”
Lobbyists in DC! If historic
buildings are exempt from the IECC, this special interest group’s
sponsor/members can’t make any money selling the materials that the proposed
code changes will require.
Like so many things, this has nothing to do with right or
wrong: it’s about big businesses making money.
The Codes Council appointed three organizations who know nothing about
how green building practices will adversely impact traditional building systems
and destroy historic fabric. Why wasn’t
the Association for Preservation Technology or a similar entity included? Why?
Because the Council doesn’t want to hear what they have to say. Under the guise of energy conservation, those
who profit from “green” building practices are determined to cut into the
historic restoration market. The end result
will be the catastrophic loss of centuries-old buildings. What do they care? The ruined, old buildings will be razed and a
“green” one can take its place. Consider
this quote from the article:
“In Boston, for example, more than 8,000 properties are
either located in one of the city’s nine Historic Districts or are designated
as a local landmark, according to the Boston Landmarks Commission. For
Manhattan alone, New York’s Landmarks Preservation Commission lists 65 historic
districts; Kerr adds that approximately a quarter of all lots in that borough
Implementation of IECC 2015, in the proposed form, will be
disastrous. I implore everyone reading
this to spread the word. Will the NTHP,
MHC and other state SHPO’s lead the charge against elimination of the preservation
exemption? Perhaps, but we must all be leaders
and cannot rely on others to advocate against this change. This is our fight and the time is now.
When new words and terminology enter our vernacular, they
often take on a connotation larger and broader than they deserve. Today, “green” and “sustainable” are
synonymous with responsible living and construction, their meanings understood as
clearly by an architect or engineer as they are by the lay person. They are buzz words that make consumers feel
good about their purchases; they’re doing their part to protect the environment
and help save the world. But, in certain
applications, use of these terms is more than a misnomer; it’s outright false
Technological advances in building science have allowed for
the creation of the most energy efficient systems and materials that the
construction industry has ever seen.
With the ever rising cost of every fuel type, energy conservation is
always a high priority when planning for and designing buildings. Buildings, historically, are only as
efficient as the technology of the day allowed.
While we may shudder with the chill of a stiff breeze standing by the
window in an 1885 Queen Anne Victorian, imagine the relative level of comfort
that one of the Pilgrims would have enjoyed in the same situation!
Today’s building designers want to create watertight, airtight
structures that use minimal amounts of energy with windows sealed tight and
year-round climate control for maximum comfort.
They strive to design an envelope that needs low or no maintenance, fully
accepting that building owners will not care for their buildings as a
given. As far as new construction goes,
there’s no problem. In fact, this is
good news. But what happens when the
owners of older buildings want to implement these new technologies to increase the
efficiency of their buildings?
Older building stock tends to be far less efficient than
modern buildings. Wall systems and
joinery, windows and doors—they’re just not as tight. An unexpected benefit of these inefficiencies
is the passive ventilation that occurs, be it laterally through windows, doors
and walls, or by the “stack effect” in which warm air rises, bringing vapor
with it, escaping through the uninsulated roof system. Know this: older buildings breath. Modern building systems are designed so that
structures don’t breath and vapor is removed with dehumidifiers or other
mechanical forms of ventilation.
In older buildings, solid masonry walls rely on the
temperature gradient between interior conditioned spaces and the outside for
walls to drain properly. Insulating
these walls stops or mitigates the passage heat through the solid brick
masonry. This slows the drainage/drying
process and traps moisture vapor in the wall which, during freeze-thaw cycles,
freezes and expands up to 12% in volume.
Oftentimes the result is damage to the wall system of the envelope. Instead, the focus should be on controlling
moisture and preventing it from entering the wall system, both inside and out.
Today, older buildings have kitchens, bathrooms and laundry
spaces that they didn’t when first built.
This introduces a significant amount of moisture vapor that may enter
the wall system from the interior.
Installation of a vapor barrier will prevent this from occurring without
impacting the thermal effect that heated interior spaces have on the exterior
walls. Outside, mortar joints must be
kept tight and full. Penetrations such
as window and door jambs must be sealed tight where they abut masonry to
prevent water intrusion.
Roof drainage systems must be functional; gutters protect
and shed the walls from runoff and properly placed leaders direct the rainwater
away from the building at grade. It’s
also interesting to note that many older masonry buildings have large windows
resulting in a high window opening-to-wall surface area ratio. Improving the efficiency of the fenestration
through conservation and repair, as well as the addition of efficient interior or
exterior storm windows, will help preserve the historic integrity of the
building while also saving on energy costs.
Recently a client contacted me with questions and concerns
about insulating his masonry walls. He
was engaged in gutting much of the interior space in his circa 1870 brick
townhouse in a National Register historic district in Boston’s South End. The building department was demanding that he
insulate behind the walls in compliance with the International Energy Conservation
Code. When we pointed out that the code
specifically exempts buildings on or eligible for inclusion on state or
national historic registers, he said it didn’t matter if there was a lot of
interior gutting; that was his interpretation of the code. Only later, when a staff member from the
Boston Landmarks Commission intervened, was he straightened out.
Before you breath a sigh of relief, owners may have to prove
that their historic projects are worthy of exemptions from the International
Energy Conservation Code following changes to the forthcoming 2015 version
approved by the International Code Council last year. The changes were proposed by representatives
from the New Buildings Institute, the Natural Resources Defense Council and the
Institute for Market Transformation and they remove the exemption language from
the code. The group added a requirement that permit applicants file a report
with a code official when seeking immunity on specific areas of their project.
Do they sound like groups that know about old buildings? No, they don’t. They sound like groups that think LEED
certification matters when it comes to old buildings; you know, organizations
that don’t think full life cycle analysis matters in “green” building
practices. Why wouldn’t the team include
representatives from the Association for Preservation Technology or the
Preservation Trades Network? And,
frighteningly, who will train the code official that decides whether a project
receives an exemption or not? The answer
is NOBODY. So guess what happens when
you encounter our friend in Boston?
More and more I’m coming to believe that these people actually
hate old buildings. I’ve had arguments
with architects and contractors who wanted to spray closed-cell foam insulation
between the rafters under slate roofs.
Some specified removing all the slate and covering the roof with an ice
and water shield membrane then reinstalling the slate, effectively “sealing”
the roof tight. Besides being an unnecessary,
exorbitant extra cost, there’s a big problem with these grand, USGBC-inspired
plans: they actually destroy the
materials in a traditional roofing system.
Slate, clay tiles and wood shingles are traditionally fastened
to battens, skip sheathing or regular old boards—not plywood, no underlayments. The roofs are water tight, not air tight and
the building breaths through the roof.
Fiberglass insulation can improve energy efficiency and reduce heat loss
without preventing the roof from breathing.
Additionally, soffit and ridge ventilation can be added if desired. Traditional roof materials like slate, clay
tile and cedar shingles experience condensation. The passage of vapor helps dry things
out. When you stop the roof from breathing
everything stays wet.
Slate is comprised of thin layers of metamorphic rock that
delaminate and fall apart when they are kept damp for months. Clay tiles, like terra cotta and brick, will disintegrate. Wood shingles rot. Steel fasteners will experience corrosion and
fail. This has been the end of many a
slate roof; I’ve pulled the slates off the roof and seen it with my own
eyes. Cedar shingle roofs will last five
years, max, when installed on a solid roof deck covered in ice and water
shield. The reality is this: greener is
not always better, especially when wielded by those unfamiliar with traditional
building systems. “The greenest building
is the one already there” is a common expression in the historic preservation
world yet it’s never heard in “green building” circles. Go figure.