About Ward Hamilton

Ward Hamilton has provided historic-preservation consulting and contracting services for more than 100 buildings in Boston, New York and throughout the New England states through his company Olde Mohawk Historic Preservation, Melrose, Mass.

Contemporary Materials Are Used to Preserve a Historically Significant 1889 House

In my capacity as a historic preservation contractor and consultant, I am often afforded the opportunity to become involved in exciting and challenging projects. Recently, my firm was awarded the contract to restore the clay tile roof turrets at Boston’s Longy School of Music’s Zabriskie House. Now part of Bard College, Longy School’s Zabriskie House is actually the historic Edwin H. Abbot House with a sympathetically designed addition built in the 1980s. The deteriorated condition of the original house’s 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 commission, building owner and a private donor.

The hipped roof turret on the building’s primary façade was in need of serious attention.

The hipped roof turret on the building’s primary façade was in need of serious attention.

BUILDING HISTORY

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 Cambridge Historic Commission re- ports 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 Buildings Survey reveals that the firm of Longfellow, Alden & Harlow designed the Richardsonian Romanesque portion of the building and that Norcross Brothers Contractors and Builders was the builder of record.

Alexander Wadsworth Longfellow Jr. (of Longfellow, Alden & Harlow) was the nephew of the famous poet Henry Wadsworth Longfellow and an important figure in U.S. architectural history. After graduating from Harvard University 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 in Pittsburgh and the City Hall in Cambridge.

Norcross Brothers Contractors and Builders was a prominent 19th century American construction company, especially noted for its work, mostly in stone, for the architectural firms of Henry Hobson Richardson and McKim, Mead & White. Much of the value of the Norcross Brothers to architectural firms derived from Orlando Norcross’ engineering skill. Although 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. Norcross was able to execute the new design.

BUILDING STYLE

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. Although the building is trimmed with 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.

Scaffolding was erected that would make the otherwise dangerous, heavy nature of the work safe and manageable.

Scaffolding was erected that would make the otherwise dangerous, heavy nature of the work safe and manageable.

The roof is covered in a flat, square orange-red clay tile. Richardsonian Romanesque buildings are almost exclusively roofed in clay tile; Monson black slate; Granville, N.Y., red slate; or some combination thereof. It should be noted that because their need for stone was outpacing the supply, Norcross Brothers eventually acquired its own quarries in Connecticut, Georgia, Maine, Massachusetts and New York.

The roof framing system of steel and terra-cotta blocks is relatively rare but makes perfect sense when considered in context with the latest flooring technologies of the era. A network of steel beams was bolted together to form the rafters, hips and ridges of the frame. Across each is welded rows of double angle irons (or inverted T beams). Within these channels, in beds of Portland cement, the terra-cotta block was laid. The tile was 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 slate and clay tile roofing systems is the sheet-metal flashing assemblies. Over the years, there must have been numerous failures, which led to the decision to remove the clay tiles from the broad fields of the roof and replace them with red asphalt shingles in the 1980s. Confronted with the dilemma of securing the shingles to the terra-cotta substrate, a decision was made to sheathe the roof with plywood. Holes were punched through the blocks and toggles used to fasten the plywood to the roof. In an area where the asphalt shingles were removed, more than 50 percent of the plywood exhibited varying degrees of rot caused by the normal passage of vapor from the interior spaces.

Fortunately, the turrets had survived the renovations from 30 years before. A conical turret in the rear and an eight-sided hip-roofed turret on the north side needed only repairs which, while extensive, did not require addressing issues with the substrate. The 16-sided turret on the primary façade of the building was in poor condition. Over the years, prior “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 previously described turrets.

As the clay-tile roof covering was removed, the materials of the substrate were revealed and conditions were assessed.

As the clay-tile roof covering was removed, the materials of the substrate were revealed and conditions were assessed.

The substrate was examined closely and, save for thousands of tiny craters created by the original nails, found to be sound. A new system had to be devised that could be attached to the terra-cotta blocks and allow for the replacement tiles to be securely fastened, as well as resist the damaging forces of escaping moisture vapor. Cement board, comprised of 90 percent 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 deal- er in Illinois and secured with stain- less-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.

CONTEMPORARY UPDATES

Although 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 “modern” technologies that pointed us toward contemporary means and methods. Rusting steel nails in the terra-cotta block were brilliant for initial installation but seemed ill conceived for a second-go-round. Instead, using non-ferrous fasteners and a new substrate that is impervious to moisture infiltration will guarantee the turret’s new service life for the next 125 years or more.

ROOF MATERIALS

Self-adhering Membrane: Grace Ice & Water Shield
Masonry Anchors: Tapcon
Cement Board: James Hardie
Stainless-steel Roofing Nails: Grip Rite
Replacement Tiles: Renaissance Roofing Inc.

PHOTOS: Ward Hamilton

Carefully Select Roofing Materials to Maintain the Character of Historic Buildings

Selecting a historically appropriate roofing material is often restrictive as a simple matter of economy. Not everyone can afford a new slate roof. But individually landmarked structures and those in local historic districts are often monitored by historic district commissions (HDCs) that typically require property owners to replace in-kind or with an otherwise historically appropriate material.

Although the preference is replacement in-kind, an intelligent argument for an alternative can often be made. The HDC can consider other materials that were available at the time of construction, as well as what buildings of similar style in the community have on their roofs. A Queen Anne may have started with a polychromatic Vermont slate roof, but the commission can consider that nearby Queen Annes have monochromatic Monson slate or even cedar shingles. A Greek Revival may have a silver-coated tin roof, but few would argue with a homeowner willing to replace it with standing-seam copper. Let’s look at several American building styles and the materials used to roof them.

Colonial Styles, 1620 to 1780

From the New England Salt Box to the Dutch-vernacular homes of upstate New York, the earliest structures in the American colonies were roofed with wood shingles.

From the New England Salt Box to the Dutch-vernacular homes of upstate New York, the earliest structures in the American colonies were roofed with wood shingles.


From the New England Salt Box to the Dutch-vernacular homes of upstate New York, the earliest structures in the American colonies were roofed with wood shingles. It is a myth they were covered with hand-split shakes because these sometimes do not hold up well. Wood shingles were easily made by planing down the shakes to a uniform thickness for ease of installation.

In the Northeast, Eastern white cedar was the typical material used while cypress was often used in the South. Western red cedar was not used much in the eastern U.S. until after the 1850s and should not be considered appropriate on a circa-1820, Federal-style structure in Connecticut. Eastern white cedar, however, rarely lasts longer than 10 years in a roofing application. Instead, preservation architects now specify Alaskan yellow cedar. Predominantly distributed from British Columbia, this dense wood is favored because of its longevity and because it develops a silvery patina, like Eastern white cedar, within one year.

Federal and Neoclassical Styles, 1780 to 1820

Many of these buildings have low-slope roofs and are often obstructed by a balustrade that runs across the top of the eaves. In congested, urban environments, the roof may not even be visible from the street. This raises the obvious question: What needs to be done when an element of the exterior is not within the street view? Most HDCs use that standard question to limit their purview over a proposed alteration. If your roof falls into this category, then you should pick the most enduring and sustainable material you can afford.

These structures were not often originally covered in slate, though many are today. Original roofs were wooden shingles—less than ideal on a roof with a shallow pitch. In limited instances, standing-seam or flat-lock-seamed roofs are seen on these building styles. To find out what’s appropriate, check out roofs on structures of the same style in your neighborhood and neighboring communities.

The mansard roof is the character-defining feature of the Second Empire style. A mansard is essentially a hipped gambrel. The lower roof, between the eaves and upper cornice, is most often covered in slate.

The mansard roof is the character-defining feature of the Second Empire style. A mansard is essentially a hipped gambrel. The lower roof, between the eaves and upper cornice, is most often covered in slate.

Greek Revival, 1820-50

This style also features a low-slope roof, typically 4:12. Although the original roof material may have been wooden shingles, many of these roofs in the Northeast were replaced by a more sustainable material long ago. Flat-lock tin or terne-coated steel were typical from the late 1800s on. Because many of these structures also have box gutters at the eaves, keep in mind that relining these systems is costly and will need to tie in to the new roof material. (See “Traditional Gutter Systems in North America”, March/April issue, page 56, or bit.ly/1Mw7Qek.) It is not uncommon for an affordable membrane, like EPDM or TPO, to be used on the majority of the roof while a costlier appropriate material, like copper, covers the visible, projecting “porch” roof.

PHOTOS: Ward Hamilton

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Built-in Gutters Should Be Carefully Inspected, Restored and Maintained

Sheet-metal gutter linings, whether made of copper, lead or both, are relatively involved and require the services of a highly skilled artisan craftsman.

Sheet-metal gutter linings, whether made of copper, lead or both, are relatively involved and require the services of a highly skilled artisan craftsman.

Built-in gutters may be the most complicated system in the building envelope, yet they are also the most elusive when you start searching for information about them. Sometimes called Yankee gutters, box gutters or even Philadelphia gutters, it’s no wonder they remain a mystery to many. Built-in gutter systems are actually built into the cornice structure and drain through internal or external leaders. They are not readily visible from the ground, further lending to the mystery of their design and function. Because they are integrated into the structure, built-in gutter linings that fail will cause extensive damage to the cornice and sometimes also the interior of the structure.

In “Traditional Rainwater Conductor Systems of the 18th and 19th Centuries,” Karen Dodge of the U.S. National Park Service, Washington, D.C., states built-in gutters were first adopted in North America during the 18th century in high-style Georgian and Federal-style buildings, usually institutional or commercial, where refined architectural qualities were desired. Although built-in gutters are highly functional, they also serve an aesthetic purpose. As structures were erected in the classical order with elaborate cornices and entablature, it became necessary to collect and channel rainwater without detracting from the architectural character of the building. Built-in gutters served this function well, hidden from sight and shedding water to the exterior.

Built-in gutters, today, are typically constructed in the same manner as they have been since the 18th century. They are wooden boxes with bottoms sloped toward the outlets where water is drained to leaders, or conductor pipes, that channel the water away from the building. The first gutters in this style were actually troughs or box gutters, carved out of wood and rubbed with linseed oil or painted to protect the wood. Corners and seams were bonded with lead wedges. Needless to say, maintenance was critical to their success or failure. Later, the advent of sheet lead allowed for broader gutters, as linings covered the wooden troughs. By the end of the century, copper became available in the U.S. and a popular choice for gutter linings because of its durability and the functional nature of the material in a sheet-metal application.

INSPECTION AND MAINTENANCE

The most common sign of water penetration is peeling paint and decay in the wood soffit under the gutter. Other signs are dark stains and mildew or deterioration of masonry. Water infiltration may be visible in attic spaces or areas beneath the gutters where plaster and other interior finishes evidence water damage. The sooner a leak or area vulnerable to failure is addressed, the smaller the scope and cost of repairs. Cleaning out leaves and debris from gutters as often as necessary is essential for durability and proper performance.

Careful inspection by a competent roofer is critical to the longevity and success of the system. He or she will look for defects, such as localized damage caused by fallen limbs or other debris, cracks from expansion and contraction at joints or folds, or pinholes from corrosion. Roofing tar and other bituminous compounds should never be used to patch, repair or coat gutter linings. It makes the condition of the gutter indeterminable, corrodes metal linings, will crack and fail quickly, and cannot be removed without destroying the lining. Ice damming is not uncommon in the winter but should not be removed with sharp tools for obvious reasons.

When tin or terne-coated steel gutter linings fail, water intrusion will occur and cause wood rot. Eventually, architectural details will be lost and replacement will be necessary.

When tin or terne-coated steel gutter linings fail, water intrusion will occur and cause wood rot. Eventually, architectural details will be lost and replacement will be necessary.

RESTORATION

Restoration of long-neglected built-in gutter systems that leak and have caused decay in the cornice and roof structure is often complicated and can be costly. But once the work is completed, a regularly maintained, well-detailed system can last 60 to 100 years or more, depending on the life of the metal lining. A preservation architect or consultant should inspect the building, propose treatment options, develop working drawings and specifications, and supervise bidding and construction. Temporary protection and permanent repairs should be performed by a roofer experienced in this specialty on historic buildings.

“We encourage restoration of historic built-in gutter systems,” says Michael Devonshire, a building conservator and principal at Jan Hird Pokorny Associates, New York. “The use of modern building materials as an adjunct to traditional materials boosts longevity.” Devonshire states the typical steps involved with a built-in gutter restoration involve:

  • Removing the gutter lining and 2 feet of the roof covering above the curbing of the gutter.
  • Repairs to rotted or otherwise deteriorated frame work. Where rafter ends or lookouts are rotted, install sisters (new rafter ends adjacent to old ones) or scarf in new wood and sisters.
  • Replacing the old wooden gutter bottom with a sustainable wood material, such as cedar or kilndried- after-treatment (KDAT) plywood. KDAT is treated for resistance to decay, minimal expansion and contraction, and increased longevity.
  • Installing the gutter lining: an elastomeric ice-and-water shield on the bottom (not always required); building felt; a slip-sheet of rosin paper; and copper on top (16 or 20 ounce, depending on the dimensions of the gutter).
  • Installing the roof covering on the roof deck above the gutter. This includes 2 feet of elastomeric ice-and-water shield (or copper flashing) beneath.
  • Repairing or replacing cornice mouldings, brackets and other architectural woodwork.

PHOTOS: WARD HAMILTON

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