Preservation in Action

The most important component of any plan to preserve an historic structure is maintenance. As soon as a building is constructed or rehabilitated, the natural process of deterioration begins. Preservation has been defined as “the act or process of applying measures necessary to sustain the existing form, integrity and materials of an historic property. Work, including preliminary measures to protect and stabilize the property, generally focuses upon the on-going maintenance and repair of historic materials and features rather than extensive replacement and new construction.”

Regular inspection and maintenance of systems will help preserve the integrity of historic building fabric. If that fabric is maintained, deterioration will be minimized or eliminated. Maintenance is the most cost-effective method of extending the service life of a building system. By logical extension, maintenance is the key to preservation. While the decay of components of the envelope cannot be avoided, neglect can actually cause this process to increase at an exponential rate. When maintenance has been deferred, and a problem suddenly rears its ugly head, it is not uncommon for the reaction to be swift and inappropriate. The use of the wrong materials and methods will often cause worse damage to irreplaceable historic building fabric.

When considered in the long term, the cost to maintain historic structures is significantly less than the restoration of historic systems and materials, and it creates far less disruption to building occupants. When property owners or managers create a maintenance program for their buildings, it is strongly recommended they seek the counsel of a preservation consultant, experienced contractor or both. The maintenance program should clearly identify and describe courses of action that are specific to the building. Every historic structure, no matter how small, should have a written guide that includes the following.

• Lists and schedules for periodic inspections of each system. These should be set up in a checklist format, to ensure uniformity of procedures over time.
• Blank elevations of the building to be marked up during inspections and after any work takes place.
• A full set of actual photographs that comprehensively document the conditions of the entire structure as well as a digital copy of each. This album will grow over time.
• A list of contractors who can be called upon in an emergency, especially an HVAC expert, electrician, plumber and roofer.
• Individualized procedures for the historically appropriate handling of the individual systems and materials of the building.
• Hard copies of completed reports that document all work and inspections. Include copies of estimates, contracts, warranty cards, paint colors, mortar recipes, materials sources and any other information that will be needed by future stewards.

Maintenance is the most important preservation treatment for extending the life of an historic property. It will slow the natural process of deterioration and prolong the natural service lives of the historic fabric of the envelope. A written maintenance plan will help preservation planners organize their tasks, schedule inspections and guide the work necessary for an historic building.

Every historic structure, no matter how small, should have a written guide. When the full life cycle of a building is considered, there is no smarter money spent than on maintenance.

editorial Uncategorized

Selecting an 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.

While the preference is typically “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 with copper standing seam. This blog article will 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. It is a myth that they were covered with hand-split shakes, because these do not hold up well, rotting and failing in just a few years; ask anyone who has made the mistake of using them. 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 ten 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, within one year.

Federal and Neoclassical Styles, 1780 to 1820

Many of these buildings have low-sloped 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, although many are today. Original roofs were wooden shingles, less than ideal on a roof with a shallow pitch. In some 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.

Greek Revival, 1820 to 1850

This style also features a low-sloped roof, typically 4:12. While the original roof material may have been wooden shingles, many in the Northeast were long ago replaced by a more sustainable material. Flat-lock tin or terne-coated steel were typical from the late 1800s on. Many have standing-seam roofing, although this system tends to be less conducive to the many and varied changes in the roof plane that multiple roofs and additions create.

Because many of these structures also have box gutters at the eaves, keep in mind that re-lining these systems is costly and will need to tie in to the new roof material. It is not uncommon for an affordable membrane (like EPDM or TPO) to be used on the majority of the roof and a costlier, appropriate material (like copper) to cover the visible, projecting “porch” roof

Gothic Revival, 1840 to 1860

While many of these structures were initially covered with wooden shingles, many had decorative styles and patterns. This was also a popular style when the slate industry in Vermont, Pennsylvania and Virginia started to produce roofing slate in such quantities that it could be realistically specified as a material choice. The influence of architect Frank Furness and others shone through, as polychromatic slate patterns adorned the Gothic “cottages” of Alexander Jackson Davis, Andrew Jackson Downing and their many disciples. In the South and in the Mid-Atlantic states, standing-seam roofing is quite common.  Again, check out roofs on buildings of the same style in your neighborhood and neighboring communities. What’s appropriate?

Italianate, 1845 to 1875

While many Italianates have out-of-sight, low-sloped roofs that an HDC will not be concerned about, many of the “villa” variety have gables and other roof planes that are visible from the street. Like those on Greek Revivals, these roofs were often clad in flat-lock seamed or standing-seam sheet metal. In later years, many were re-roofed with clay tiles. Note that the advent of this new material correlates with the growth of the Ludowici firm in Chicago in the 1880s. The HDC will likely require replacement in-kind to create the original look, although there may be some leeway with respect to the material itself. After all, it’s all about keeping up appearances.

Second Empire, 1855 to 1880

The mansard roof is the character-defining feature of this style. A mansard is essentially a hipped gambrel.  The lower roof, between the eaves and upper cornice, is most often covered in slate. More often than not, these parts of the roof can be restored and do not need to be replaced. If they do need replacement, be prepared to face an HDC that’s going to want it done in-kind. Keep in mind that these structures almost always have (or had) a built-in gutter at the eaves.

The sheet-metal linings fail, and replacement is expensive – especially if they failed long ago and wood rot has resulted from the neglect. The upper roof typically ranges from flat to a low-sloped 4:12 pitch. Once the roof becomes visible from the street, the material choice becomes important, and the same argument applied to Greek Revival and Italianate styles holds true here.

Queen Anne, 1880 to 1910

Severe recessions in the U.S. during the 1870s stymied new construction. By the time the economy rebounded, the Queen Anne had replaced the Second Empire as the popular style of choice. Improvements in rail service, as well as material fabrication and production, were game changers. Architects and builders roofed these Victorians with various slate colors, cedar shingles, and flat-lock and standing-seam copper, along with different colors and shapes of clay tiles. And, often, these buildings have combinations of roofing materials and styles.

Unfortunately, many HDCs allow building owners to replace original roof fabric with so-called “architectural shingles.” These shingles were created to replicate wood shingle (or shake) roofs in an economical way. It is a fallacy that they are an appropriate alternative to slate; in fact, three-tab shingles look more like slate than architectural shingles do. Before you replace your entire roof, consider that it may only be the flashings that need replacement.

editorial Uncategorized

 
The timber-framing system is a centuries-old method developed by medieval Europeans. Its fundamental precepts have remained in place since then, but the physical manifestations of these fundamentals have taken on a variety of shapes. In America, from 1600-1900, we can see this variety develop. This blog is based in large part on a paper I wrote in 2010 while working on a master of science degree in historic preservation at the University of Massachusetts-Amherst. It explores major American framing systems in three sections and will provide an overview of the components and interrelations of a basic frame, examine how joining techniques (practice) is influenced by stylistic concerns (aesthetics) and compare a 19th-century New England house to a 19th-century Chesapeake house.

Basic Framing Techniques and Theory
The whole unit represented in a complete timber frame may be broken down into three subsections in order to better understand the intra- and inter-workings: the floor frame, the wall frame and the roof/ceiling frame. The floor frame is a combination of “… posts, beams, sill plates, joists and subfloor” (Anderson, 2002, p. 19). The components that comprise the floor frame are arranged in order to reduce the amount of shrinkage and settling of the wall and roof frames. Said movements are owed to internal and external factors: the moisture content of the wood, combined with the stresses and strains inherent in a frame, and the external forces of nature and living to which a frame is exposed. Post and beam meet at a 90-degree angle at the ends of the structure, providing a horizontal base and vertical extension. The beams are crossected by joists, which provide lateral support and stiffness to the frame. The sub-floor does not provide structural support; it provides a skin for the interior flooring.

The floor frame provides a basis upon which a wall frame can be constructed. Anderson recommends the following wood types for use in wall frames: Douglas fir, hemlock, southern pine, spruce and white fir. The reasons he gives for these specifications are “… good stiffness, freedom from warp, good nail-holding ability and ease of working” (ibid, p. 31). The components of a wall frame include the vertical studs and their horizontal counterparts. The former are divided into the following types: single story and two story. The latter are comprised of bearers, girts, window headers/sills, top plates and joists. Additionally, single-story studs may be reinforced by diagonal braces; these braces relieve pressure between beam and post, while adding stability to the studs.

The basic form of the roof frame in a timber-frame structure, the gable roof, is composed of the following elements: rafters (extending on a diagonal axis from the top plate and terminating at the top of the frame), the ridge board (the horizontal piece that forms the top of the frame and to which the rafters are secured), the end stud (the roof version of the single/two-story stud), collar beams (which provide lateral support between the rafters) and ceiling joists. Anderson mentions three types of gable roofs: 1) the simple and familiar triangular form described above, 2) the gable dormer – featuring a windowed, protruding form from the roof and 3) the hip – which features triangular forms in the front and back and trapezoidal forms on the sides.

Timber Framing and Balloon Framing
The move away from timber framing toward balloon framing began in the 19th century, and although balloon framing is not the subject of this blog, it does provide a helpful contrast for understanding the history, evolution and aesthetic of the timber frame. Old-House Journal magazine notes that “the basic difference[s] between timber and balloon framing [are] that in balloon framing every stud in the frame is a load-carrying element…[and] mechanical fasteners (nails) [substitute] for… elaborate woodwork joints (mortise and tenon, etc.)” (1980, p. 197). Thus, the move from timber to balloon framing occurred due to economic considerations: the balloon frame used less material, took less time to construct and required a more standardized and teachable skill set.

When the Puritans came to America and settled in what would become the 13 original colonies of the U.S., they brought with them framing techniques practiced in Europe for centuries. The tradition of European framing had been passed down through these centuries owing to the artisanal guild system, which, having been created in the Middle Ages, provided a trans-national system of teaching and developing construction techniques. The guild system would remain in place until the Industrial Revolution (exactly the time that balloon framing overtook timber framing as the preferred method of house construction). The basic joining technique was comprised of a mortise-and-tenon system, a system that was developed in order to solve the fundamental problem of construction: how to join a post and beam at a 90-degree angle? The ancient Greeks had bypassed this problem with a post and lintel system; the Romans innovated with the arch. Medieval Europeans developed a female/male adapter system.

The mortar-and-tenon process is a manual labor-intensive process. The mortise cavities and tenons are formed with adzes. Additionally, the means of connection vary according to the training and preference of the carpenter in question. Conversely, in historical terms, mechanical means of joining and producing uniform studs limited the ways in which frames could be joined. Old House Journal notes that distinguishing between a timber and balloon frame is difficult to do from an outside perspective; however, “… on the inside, there are usually tell-tale signs. The posts and summer beams are so big they usually protrude from walls and ceilings” (ibid). Two reasons explain the size differential: 1) before builders had access to mechanical means of cutting wood, all of the timbers used in a frame had to be cut down from a nearby forest then planed and measured by hand; and, 2) the weight of a timber-frame structure is dispersed among the beams and posts – whereas, in a balloon-frame structure the load is spread evenly among the studs, braces, and other elements.

Changes in Joinery Techniques
The exposed interior common to timber-framed structures led early American constructors to innovate in their approaches to joining techniques. It seems clear that the exposed interior posts presented a problem because they gave houses an unfinished structure. Jan Leo Lewandoski catalogs eight types of joining methods: 1) exposed decorated, 2) cased, 3) cornered, 4) deep wall, 5) thin wall, 6) vertical plank, 7) skeleton plank and 8) balloon (1995, p. 42). Without covering all the individual differences, it may be helpful to point out how these different techniques “solve” different “problems” presented by the timber-frame structure. The easiest way to deal with the problem of the exposed frame was to hand decorate it. The exposed decorated technique did not change the method of fastening; it simply altered the appearance of the exposed beam by fashioning its edges with “… chamfers, ovolos and beads…” (ibid, p. 43).

Another technique that did not change the joining method (but only hid the exposed post) was adding casing, or draping the post with a skin that matched the walls. The cornered method simply cut out a section of the post so that it would be plumb with the wall, and the deep-wall method extended the depth of the wall so that it would correspond to the thickness of the post. What each of these methods points to was the fact that there was something fundamentally disturbing to early Americans about the exposed interior. Lewandoski traces this disturbance to a shift in aesthetic sensibility: “[Early Americans] admired Greek and Roman structures, [which] were built of masonry and had sharp, straight interior lines. [They] sought to summon up the appearance of the masonry public buildings of the classical world in the average wooden residences of the new world” (ibid, p. 44). Interestingly, Lewandoski implies that trends in the development of timber framing were not simply practical. They also had their origin in how people conceived of the ideal living space. Said space would not be interrupted by protruding hand-hewn posts.

Willie Graham, performing further research in the same area, examines the way that pre-industrial framing systems developed in order to deal with practical and theoretical concerns. He defines the system of pre-balloon framing in America as an example of a “vernacular” style, as opposed to an industrial style (2003, p. 179). The former represents a particular response to a specific problem of carpentry. The response is determined by the carpenter’s experience and training. The carpenter’s experience and training are determined in part by the unique conditions of his environment. Graham notes that the unique environmental conditions of the Chesapeake area were an abundance of wood and a lack of skilled labor.

Stylistic Flexibility of Timber Framing: Analysis
The flexibility of the timber-framing process may be understood in further detail by examining two historical examples of its exteriors: the Bryant Cushing house in Massachusetts and the Chesapeake-style house – both from the 19th century (Library of Congress, 2010, web). The Cushing house is a two-story, rectilinear affair. Its two symmetrical halves are bisected in the middle by the entrance. Lewandoski’s point about early New Englanders’ desire to emulate Greek and Roman architecture is well taken in this example: The entranceway is done in the Doric Greek style with a column, architrave, frieze and cornice. Additionally, the Cushing house is a fine example of a building method that stresses proportionality, regularity and simplicity.

The Chesapeake house is different. It is two stories, but its second story is contained within a gabled and dormered roof. Its doorway and windows do not imitate any style; they seem to be nothing more than simple and practical openings. The horizontally oriented planks that cover the first story are irregular. If Graham’s point about the lack of carpentry skills available to Marylanders is correct, it is especially so when considering this example.

Conclusion
The structure and style of American timber-framing systems up to 1900 are owed, first, to practical considerations and historical determinates and, second, to aesthetic sensibilities. Additionally, the environment in which carpenters work influenced them more 200 years ago than it does today. This is owed to factors such as standardized education, mechanization of building processes and the ability to transport materials across long distances. Despite the fact that the timber-framing method was eventually overtaken by the more economical balloon-framing method, it is still interesting and beneficial to examine the differences within the timber-framing method. These differences speak at once to the diversity and similarity of the American building heritage.

Glossary of Terms
Bay. Section of a framed building between principal supporting posts.
Bent. Post and plate, or post and girt assembly. Posts are mortised into the plate or end girt making a U-shaped section of the house frame.
Collar beam. Horizontal timber connecting principal rafters below their apex and above their base.
Girt. A main horizontal timber placed between the wall plate at the top and the sill at the bottom.
Joist. One of a number of horizontal timbers supporting a floor or carrying a ceiling.
Lath. Narrow timber (1 to 2 ins. in width) used in a partition as a base for plaster, or on rafters to support the roof covering.
Plate. Horizontal timber on top of the wall frame, supporting the rafters.
Post. Strong vertical timber that is part of the main framework of a building.
Purlin. Horizontal timber that ties together the principal rafters and supports the common ones.
Rafter. Timber set at an angle; supports laths under the roof covering including:
principal rafters–inclined timbers that coincide with the main posts of the framework and support the purlins; and,
common rafters–inclined timbers, lighter than principal rafters, spaced evenly between the latter along the length of the roof.
Sill. The bottommost horizontal timber resting on the footings or the ground into which the posts are mortised; wooden horizontal base of a window or door frame.
Stud. Smaller vertical timbers set between posts in the framework of the building.

BIBLIOGRAPHY
Anderson, L.O. (2002) Wood–Frame House Construction. Washington: Books for Business.
Graham, Willie. (2003) “Preindustrial Framing in the Chesapeake.” Perspectives in Vernacular Architecture, 9, 179-196.
Lewandoski, Jan Leo. (1995) “Transitional Timber Framing in Vermont.” APT Bulletin, 26, 2/3, 42-50.
“Timber-Frame Houses in the Historic American Buildings Survey.” (2010) The Library of Congress. Retrieved 5 December 2010, from http://www.loc.gov/rr/print/list/100_tim3.html
“Traditional House Framing.” (Dec., 1980) Old House Journal, 8, 12, 197-200.

editorial Uncategorized

We’ve all heard of home inspectors recommending that a chimney be repointed before the sale of a house, but what does that mean? The average Joe on the street knows what it means: “Putting the cement back in between the bricks, right?” Basically, yes; that’s right. But did you know there are different types of mortar? Did you know some have little or no cement at all? And were you aware that if you repoint with too much cement in your mortar, you might damage the masonry itself?

Did you know that “repoint” isn’t even, technically, a word? Even though it’s used by architects and practitioners in professional documents, dictionaries don’t recognize it. But that’s a topic for another blog. (Don’t get me started.)

First, a little Mortar 101 is in order. Mortar is typically made up of three dry components: a binder, an aggregate and lime. This is usually Portland cement, sand and hydrated lime. It’s the ratio that determines the strength, or ASTM classification, of the mortar. The pre-mixed bags found at home centers are usually ASTM type “S” mortars, similar to those used on commercial construction sites to lay modern brick and block walls. They contain lots and lots of Portland cement and probably differ wildly from the mortar found in the average historic home.

Before 1872 in the United States, there was no such thing as Portland cement. Mortar was generally lime and sand mixed or lime, sand and natural cement (discovered in the 1820s during construction of the Erie Canal in upstate New York).

The paradox of a masonry structure is that its strength comes from its ability to fail. Well, what the heck does that mean? you’re wondering. And rightly so.

Here’s how an old friend best explained it to a class of preservation students. Masonry units, be they brick, stone or block, are laid in mortar. That mortar absorbs and expels moisture. Moisture is water, and water freezes. When it freezes it expands, increasing volume by as much as 12%. So, in a sense, the mortar expands, even minutely. Something has to give: the brick or the mortar.

If the mortar is “harder” (meaning a high cement content) than the bricks laid in it, the bricks will spall and pop, their faces crumbling and falling off. But if the bricks are “harder,” the mortar will give, often without cracking or falling apart or leaving any visible record of the strength through failure. And if the mortar joints do fail, it’s far less expensive to repoint masonry than it is to rebuild it.

A good mason will be able to mix up a repointing mortar that will not jeopardize the historic masonry fabric of your home or building. If the color or texture are more challenging, there are firms available online that will custom match mortar samples for under $200. That’s right folks. You can cry “Foul!” the next time a mason says, “I can repoint your brick wall, but I can’t match the old joints where they meet.” Or, “it’ll take a couple years for it to blend in, if ever.” Or, worst, “It’ll never match.”

This is the same guy who buys bags of pre-mix mortar at Home Depot and repoints old, soft-brick chimneys. After a couple of winters, the chimney is crumbling and falling apart. If he’s really slick, the owners unwittingly call him back to rebuild the chimney that he destroyed!

A good repointing job should last at least 30 years. But, like most things in life, you get what you pay for. The cheapest guy, or the one who says “I can’t match it,” will look like a deer in the headlights if you start using terms like compressive strength, Portland cement or lime putty mortar. If you start to think, “Maybe I know more about this than he does,” you probably do.

You should ask for three references – specifically, for recent repointing jobs – and then go look at his work. A good masonry contractor will not spend his time forever going back and forth with you providing endless references and answering questions ad nauseam. He’s busy, in demand and doesn’t desperately need your job. But he’ll give you a comprehensive consultation and estimate, and he’s got a hal dozen references ready for a potential customer. Once you find him, hire him.

editorial Uncategorized

In late October, Hurricane Sandy careened up the Eastern Seaboard and tore across the Northeast corridor causing over 250 deaths and $65 billion in damage along the way. High winds, driving rain – the stuff that makes us pause and look up at the roof.

How does slate hold up as a material choice? ASTM (formerly, the American Society for Testing and Materials) has established a standard specification for roofing slate, C-406, which tests the slate for the three physical requirements that it must pass to be classified as an S-1 top-grade material.

ASTM C 120 – Modulus of rupture. This test determines the breaking load, modulus of rupture and modulus of elasticity of slate. The modulus of elasticity is not overly important for roofing slates but should not be entirely discounted.

ASTM C 121 – Water absorption of slate. Porosity of the material is tested by submerging the slate samples in water for defined periods and then gauging absorption.

ASTM C 217 – Weather resistance. This standard defines the depth of softening as an expression of weather resistance of a slate. The depth is determined by a shear/scratch tester or a hand scraping tool.

In August of 1992, Hurricane Andrew devastated southern Florida and entered the history books as the costliest hurricane in U.S. history (a record held until Katrina in 2005). After a decade of staggering losses from sub-standard building practices and materials, the government in Miami, FL, decided to do something about it. Legislators passed new standards, testing and licensing that raised the bar higher than anywhere else in the United States. In order to sell your construction materials there, they must be “Miami-Dade-County-approved” after first passing a battery of stringent tests.

This testing includes a wind up-lift test in which slate was tested on a roof and subjected to 110-mph winds with gusts up to 140 mph with no movement detected. Slate was also subjected to a wind-driven rain test in which 90- to 110-mph winds were blown against a 2:12 pitch roof, while 8.8 inches per hour of rainfall were simulated.

The result? No water penetration was detected underneath afterward. This testing is by far the most severe test for roofing products to pass, and only clay tile materials could come close to the performance of slate. Couple that with a 100-year (or more) warranty, and slate is the epitome of sustainable green building material choices.

editorial Uncategorized

Pick up any home improvement magazine or journal and you can’t help but find articles and stories on how to find and hire a contractor. “Get five bids, and throw out the highest and the lowest.” “Verify their insurance.” “Call references.” They’re rife with advice. But these articles always fail to address a topic critical to the success of the project: finding the right contractor for the job at hand. While it seems like an obvious statement, and a simple enough obstacle to overcome, it is the single most important element to the success of the project and your satisfaction – ultimately – as the customer.

No contractor is a master of all skill sets in a given trade. Let’s look at roofing as an example. There are some roofing outfits that do nothing but install standing-seam metal roofs. Because it’s all they do, they’re set up for it. They have the tools, equipment and crews who are proficient in that work. This allows them to offer a quality product at a competitive price. Now, consider the roofer whose company primarily installs asphalt shingle roofs for residential customers. He may be able to successfully complete a standing-seam metal roof project, but there’s a lot more planning and set-up involved; and he may have less skilled workers for that particular project. Hence, his price is likely to be higher, and there will be fewer examples of his work for you to consider. The contractor you hire must have the tools, equipment, craftsmen and experience needed to successfully complete your project.

Consider this analogy as it applies to restoration work. The knowledge and skill sets required to successfully rebuild a copper-lined, built-in gutter on a Second Empire-style house with a slate roof bring three trades into play: sheet-metal work, carpentry and slate roofing. There are many carpenters who would find the copper work and slate aspects of the job intimidating and outside their skill set. And many slaters are not capable of replicating the ornate cornice, corbels and detail of a built-in gutter.

It is critical that a contractor provide you with more than a fancy proposal and attractive price for your project. Require bidding contractors to supply you with the address and contact information for three recent projects in which they performed the same tasks as you need performed. Call the references and ask questions. Then go out and actually look at the quality of their work. They need to demonstrate and prove themselves through pictures, documentation and references for similar projects they have already successfully completed.

Being a successful restoration contractor requires knowledge of the tools, materials and practices of tradesmen from yesteryear. One cannot rely on the best practices of modern construction alone as a basis of knowledge. Constant research through 100-year-old trade manuals, the Internet, hands-on experience and participation in professional trade organizations are the foundation on which a preservation worker bases his decisions and guides his crew through a project. It is a constant learning process and one that requires a high degree of interest and commitment to professional development. Make sure your prospective contractor is genuinely interested in the work on your home or building.

Some words of additional caution are in order. Make certain that the contractor is licensed and insured, as your city, state or both may require. Some states, like Massachusettsand and Rhode Island, require a construction supervisor’s licensing or registration with the state contractors’ board. Verification of this information is easily accessed through the Internet, but don’t stop there; make certain to contact the government entity that oversees the licensing to confirm what you find.

If a permit is required, the contractor must secure it. If you fall for the old “you pull the permit and I’ll give you a price break,” watch out! If anybody is injured or property damaged during the job, it will fall on your shoulders. Don’t cut corners to save a few bucks. Most contractors who try this scam do not have the insurance your town or city requires to grant the permit. You are making a significant investment in your home or building; don’t cut corners when it comes to a permit.

It never ceases to amaze me how few clients ask for proof of the right insurance. Your contractor must have liability and workers’ compensation insurance. General liability insurance for a minimum $1 million personal injury and minimum $1 million property damage are not cost prohibitive for a restoration worker proposing to do high-end work. A common scam many contractors employ is to purport that they have liability insurance, and that’s good enough.

Of equal or possibly greater importance is workers’ compensation insurance. This one costs the big bucks and is what drives up a legitimate contractor’s prices. However, it is also his protection and yours if an employee gets hurt on the job. If an employee gets injured on your property and files a workers’ comp claim where coverage was not in effect, he can sue his employer and you! Verify that your restoration contractor has workers’ compensation insurance and provides you with a general liability certificate naming you and the property as “additionally insured parties.”

Before you invest in the next project, do your homework. Exercising proper due diligence when screening contractors is crucial to success. Following these guidelines will help you find the right outfit for the job and get things moving in a positive direction.

editorial Uncategorized

Built-in gutters may be the most complicated system in the building envelope, yet they may also be the most elusive when you start searching for information on 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 interior of the structure.

In “Traditional Rainwater Conductor Systems of the 18th and 19th Centuries,” Karen Dodge of the National Park Service states that 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.

While highly functional, built-in gutters also serve an aesthetic purpose. As structures were erected in the Classical order with elaborate cornices and entablatures, 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.

Today, built-in gutters are typically constructed in the same manner as they’ve 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 either 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 United States, and it quickly proved to be a popular choice for gutter linings because of its durability and the functional nature of the material in a sheet metal application.

Inspecting and Maintaining Built-In Gutters
The most common signs of water penetration are peeling paint and decay in the wood soffit under the gutter. Other indications are dark stains and mildew and deteriorating masonry. Water infiltration may be visible in attic spaces or areas beneath the gutters where plaster and other interior finishes show 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 also critical to the longevity and success of the system. He will look for defects such as localized damage due to fallen limbs or other debris, cracks from expansion and contraction at joints or folds and 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.

Restoring Built-In Gutters
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 via work 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 in New York City. “The use of modern building materials as an adjunct to traditional materials boosts longevity.”

 Devonshire outlines the typical steps involved with a built-in gutter restoration.
• Strip off old gutter lining and 2 feet of the roof cladding above.
• Where rafter ends or lookouts are rotted, install sisters (new rafter ends adjacent to old ones) or scarf in new wood and sisters.
• Replace old wooden gutter bottoms with kiln-dried-after-treatment (KDAT) plywood treated for resistance to decay, minimal expansion and contraction and increased longevity; slope bottoms toward the outlet.
• Install 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-oz., depending on the dimensions of the gutter).
• Install on the roof decking above the gutter 2 feet of elastomeric ice-and-water shield (or copper flashing) and roof cladding over it.
• Repair or replace cornice moldings and interior structural elements as needed.

The Copper Development Association and the Sheet Metal and Air Conditioning Contractors’ National Association recommend the use of copper sheet metal because of its workability and durability in a roofing application. Indeed, many linings have lasted 100 years or more.

Lead-coated copper and a tin-zinc alloy-coated copper may also be specified. Aesthetically, the water staining caused by sheet copper can be minimized or controlled by using one of these alternative materials. Gutter linings are sometimes replaced with EPDM rubber or similar membranes because of a perceived cost factor. While there will be initial savings, the linings will need to be replaced more often and – ultimately – cost more in the long run.

Eliminating Built-In Gutters
It is not uncommon for the owner of an historic home or steward of a landmark structure to look at the estimated costs to restore built-in gutters and consider eliminating them from the roof system. Before doing so, they must consider the manner in which this will be accomplished: Will it require the plane of the roof to be altered? Will it be visible from the street? If so, is the property in a local historic district, which may make the work impermissible? Will new hanging gutters be added at the eaves, affecting the appearance of the cornice and further inciting the ire of local preservationists?

If not, what effect will the water have on the exterior of the building? How will the envelope be impacted? What problems could this cause in the basement or – worse – the foundation? Once these questions are realistically answered, the preservation of the built-in gutter system seems more attractive, if not a necessity. An architect or preservation consultant whose practice focuses on historic structure envelope should be consulted before any such alteration is undertaken.

Summing Up
Built-in gutters are a complicated system in the building envelope and certainly one of the most expensive to restore if maintenance is deferred. Because they are integrated into the structure, built-in gutter linings that fail will cause extensive damage to the cornice and interior of the structure.

A significant feature of the structure’s architectural character, they should be regularly inspected, cleaned, repaired and maintained. Careful, regular inspection by a competent roofer is critical to the longevity and success of the system. An architect or preservation consultant whose practice focuses on historic structure envelope should be consulted before any dramatic alteration commences.

editorial Uncategorized

Slate has been used as a roofing material for centuries inEurope. It has been the preferred choice for homes and buildings in the northeastern United States since the late 19th century. Slate roofs are still seen, frequently, in places like upstateNew York, where tremendous building and growth took place in the early 20th century during slate’s boom. Schenectady, for example, grew from a population of 13,500 in 1880 to 32,000 in 1900. Twenty years later, it was 89,000. The slate quarries of Granville, NY, andVermont lay a mere 60 miles to the north. As the housing stock grew at an exponential rate, slate was used in vernacular applications, as well as on fine homes and institutional structures.

Many of the original slate roofs from this period survive today. What does not exist, however, is a ready supply of competent, capable contractors to repair and restore slate roofs. With a basic understanding of this highly specialized roofing system, homeowners and building managers can generally assess the current condition of their slate roof, its life expectancy and, if necessary, the potential for restoration. The information that follows will help in assessing and identifying your roof’s needs as you, armed with this information, carefully screen potential roofing contractors to effectively carry out these repairs.

So what goes wrong with slate roofs? In most instances, the problem is one of the following:

• Variations in durability and quality cause troubles.

• Flashings and other metalwork need replacement.

• Earlier repairs by irresponsible roofing contractors come back to haunt.

Variations in Durability and Quality of Slate

Slate is pulled from the earth in massive slabs and dressed down into individual shingles mostly by hand. Slate is stone, and stone is long lasting. However, stone is a natural material and may have minute or even invisible fissures that will ultimately cause slates to break and slide off the roof. Roofing slates are rated by by the American National Standards Institute according to hardness. Softer slates (rated S2 or S3) may become crumbly and will delaminate, sometimes, as early as 55 years after installation and certainly by 80 to 100 years. These softer slate roofs (commonly fromPennsylvania) cannot be saved or restored, for the most part, but repairs can buy time.

Good, hard slates, like most New York,Vermont, Peach Bottom, Buckingham or Monson slates, will last for hundreds of years on a properly cared-for roof. It is critical that people who own, inspect or work on slate roofs are able to identify the slate on the roof in question. This single most important information will provide details as to its type, origin, longevity, characteristics and qualities. Roofing slate is still being quarried and sold in New York andVermont, as well as Pennsylvania and Virginia. Slate was also once quarried in Georgia and Maine (home of the world-famous Monson slate).

Flashing Replacement and Built-in Gutters

While the slate may last “forever,” the metal flashings will not. Flashings are essentially the metalwork used to prevent the penetration of water wherever there is an abrupt angle or opening in the roof (chimneys, valleys, dormers, for instance). Often, flashings were made from terne-coated steel, which is a steel coated with a combination of lead and tin. This is sometimes, incorrectly, called “tin.” Terne-coated steel has to be painted regularly, or corrosion will occur.

Copper flashings (either plain copper or lead coated) were most commonly installed on government buildings, churches and similar institutions and upscale homes. Copper will oxidize, and a green patina will appear. Copper will begin to fail after about 60 to 70 years in areas of high wear, such as valleys. The copper industry suggests a life of 80 years. Older copper flashings can be painted in order to extend their lives. Too often, the flashings fail, and unscrupulous roofing contractors persuade homeowners to replace their good, slate roofs with asphalt. Only the flashings should be replaced not the entire roof.

These types of projects are routine for slate roof restoration contractors. The adjoining slates are removed to allow for replacement of the flashings. The removed slates are then installed in their original locations, leaving the roof, in appearance, as it was before, except for the flashing. The standard upon which a repair is judged is that it must not appear to the layperson that any repair took place at all, except for new, visible flashings.

Box gutter linings, or “built-in” gutters, are another common problem on old slate roofs because the metal deteriorates and leaks. Just like valleys and other flashings, they can be replaced without removing and replacing the entire roof. If left unchecked, the entire gutter boxes will rot and need to be rebuilt and replaced.

Beware of Irresponsible Roofing Contractors

The cause of many leaking slate roofs is not natural wear, metal failures or even cracked slates. It is, quite simply, bad work. Many unqualified people claim to have the ability to repair slate roofs. Fully half of the work done annually by a typical slate roofing contractor involves the removal and replacement of faulty repair work. Owners of slate roofs often pay exorbitant sums to have them incorrectly repaired by unskilled roofers; then they have to pay even more of their hard-earned money to have them fixed and repaired correctly.

The types of abuses committed against slate roofs include the ones that are face nailed, tarred, repaired with non-matching slates, coated or re-flashed incorrectly. One should never tar or coat the surfaces of slate roofs. Such actions are aesthetically displeasing, often irreversible and ineffective. Roofing contractors are notorious for advising owners to replace a perfectly good roof because the flashings have failed and they are unwilling or unable to perform the necessary repairs. These owners will often listen to such advice when a lack of competent slaters makes it the only advice available.

These issues have been the downfall of countless slate roofs, lost forever to ignorance, neglect and despair. As you seek estimates and advice from roofers, use this information to test their knowledge and screen their methods. Watch their eyes widen as they realize you know more about slate roofing than they do!

Replacing Broken and Missing Slate

It is not uncommon for a century-old slate roof to have 50 or more slates simply fail from a variety of causes. Slate contains natural faults or hairline cracks and may eventually break. A 20-square roof (2,000 square feet), with a typical 10- x 20-in. slate, will have about 3,400 slates. If 50 of them fail after 100 years, then the failure rate of the roof is 1.5% over 100 years – or a 98.5% success rate over a century.  That’s an A+.

However, just one missing slate is all a leak needs to get started. For a professional slater, the solution is not rocket science. Replacement slates must never be fastened in place with visible straps or exposed nails.

There are two acceptable techniques for fastening replacement slates: the “nail and bib” method or the “slate hook.” The nail-and-bib method is the most widely used. The broken slate is removed with a slate ripper, and the replacement slate is anchored with a nail in the slot between the two overlying slates. A small square of flashing is slid under the two overlying slates on the next course, above, and over the new nail head. The bib is bent a little so friction keeps it in place. Bibs can be aluminum, copper or other metal that wom’t corrode, but shiny and reflective metals that are visible from the ground should never be used. Copper or brown-painted aluminum (coilstock) blends nicely into the roof.

A slate hook is a hard wire hook made of galvanized steel, copper or stainless steel, approximately 3 ins. long. A small exposed loop hooks the replacement slate in place. This is one instance when an exposed repair device is acceptable because the tiny hook is almost invisible from the ground.

Stainless steel hooks are stronger than copper hooks. Slate hooks are preferable to the nail and bib on new slate roofs, especially for repairs in the field of the roof. Using strap hangers to repair the roof should be avoided; they’re unsightly and they deface the roof.

The tool required for removing slates from a roof is the slate ripper – a sword-like object that slides up under the slate and yanks out the two nails that hold it in place. You never want to cut the nail because the piece of nail left under the slate will interfere with sliding the replacement slate into place. A slate hammer has a hole punch at one end used to punch nail holes in slates. New slates can be hard and brittle and require some practice for easy punching with a slate hammer. Standard thickness slates (3/16 in. to ¼ in.) are readily cut with a simple slate cutter.

Summary School

While the slate roof may last “forever,” the metal flashings will not. Not all slate is the same in quality and durability. Unscrupulous roofers will butcher your roof or even replace it with asphalt shingles, if you let them. Armed with the above information, you are ready to question potential slaters and assess your roof’s needs.

Ready for Grad School? Check Out These Additional Resources

Copper Flashings, 2nd ed.  Copper And Brass Research Association.

The Repair, Restoration & Replacement of Historic Slate Roofs. Jeffrey S. Levine. Technical Preservation Services, U.S. Department of the Interior, Washington, DC, p. 192.

Slate Roofs: Design and Installation Manual (2010). National Slate Association.

Secretary of the Interior’s Standards for the Treatment of Historic Properties (1993). Preservation Assistance Division, National Park Service, U.S. Department of the Interior, Washington, DC.

Architectural Sheet Metal Manual, 6th ed. Sheet Metal and Air Conditioning Contractors’ National Association.

editorial Uncategorized

What does it mean when someone says “historic restoration” or “historic preservation?” Or, for that matter, “historic?” What does it mean when we say that a building or neighborhood is on the National Register of Historic Places? Can the government tell you what you can and cannot do with your house or building? This article is designed to help answer those questions and more, giving you the information needed to successfully negotiate the historic restoration approval process.

We’ve all heard about buildings and neighborhoods on the “National Register,” but what does that mean? The National Register of Historic Places (NRHP) is the United States government’s official list of districts, sites, buildings, structures and objects deemed worthy of preservation. A property listed in the National Register or located within a National Register Historic District may qualify for tax incentives derived from the total value of expenses incurred preserving the property.

The passage of the National Historic Preservation Act (NHPA) in 1966 established the National Register and the process for adding properties to it. Of the more than one million properties on the National Register, 80,000 are listed individually. The rest are contributing resources within historic districts. Each year, approximately 30,000 properties are added to the National Register as part of districts or by individual listings.

For most of its history, the National Register has been administered by the National Park Service, an agency within the United States Department of the Interior. Its goals are to help property owners and interest groups, such as the National Trust for Historic Preservation, coordinate, identify and protect historic sites in the United States. While National Register listings are mostly symbolic, their recognition of significance provides some financial incentive to owners of listed properties. Protection of the property is not guaranteed. During the nomination process, the property is evaluated in terms of the four criteria for inclusion on the National Register of Historic Places.

Oversight for these buildings is managed at the local level. Historic district commissions, preservation committees and similarly titled municipal entities are empowered to govern and permit (or deny) private citizens’ work on such buildings–if legislation exists that empowers them to do so. In other words, a house that is on the National Register but not in a local historic district or in an area where the local laws do not exist to protect the structure is not protected. The decision-making process is guided by the Secretary of the Interior’s Guidelines for the Treatment of Historic Properties. The Secretary’s guidelines categorize the rehabilitation of historic structures under four headings. They are listed below in order of most desirable treatment to least.

Preservation focuses on the maintenance and repair of existing historic materials and retention of a property’s form as it has evolved over time.
Rehabilitation acknowledges the need to alter or add to a historic property to meet continuing or changing uses while retaining the property’s historic character.
Restoration is undertaken to depict a property at a particular period of time in its history, while removing evidence of other periods.
Reconstruction re-creates vanished or non-surviving portions of a property for interpretive purposes.

Choosing the most appropriate treatment for a building requires careful decision-making about a building’s historical significance, as well taking into account a number of other considerations.

Importance: Is the building a nationally significant resource? Did an important event take place in it?

Condition: What is the existing condition of the building prior to work?

Building Use: Will the building be used as it was historically or will it be given a new use?

Building Code: Regardless of the treatment, code requirements will need to be taken into consideration.

The historic district commission exists to help preserve the heritage of the region’s built environment. Assuming that these standards are followed and that details and elements of the structure’s envelope are to be preserved (or replaced “in kind”), approval should granted. Thoughtful consideration of the process used to approve or reject proposed actions before making application will increase the likelihood of your plan being approved.

Admin Uncategorized