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
long-lasting roof.
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,
Massachusetts.
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.Contact us today by clicking here.
