Tuesday, July 24, 2012

Preservation thought for the day

“Historic preservation is, ultimately, not about buildings, it is about culture – which is about humanity. Our cultural trajectories result in our understanding of the technologies that permit us to shape Earth-formed materials into buildings. Buildings become the shelters and settings in which we enrich ourselves more fully. Cultural preservation – in all of its diverse forms – is as important as the preservation of buildings, if we are to fully understand what it is to be human. The saving and passing on of buildings of significance helps us to resist cultural stagnation and fosters sustained renewal”
    Michael Devonshire, Commissioner on the NYC Landmarks Preservation Commission and Director of Conservation at Jan Hird Pokorny Associates

Sunday, July 22, 2012

More than a mansard roof: The Second Empire style

The Second Empire revival was a very popular style of European origin and is my favorite style to work on. The mansard roofs, tall floors and heavy moldings of the style came to epitomize nineteenth century Americana. Like other styles borrowed from Europe, American builders and architects transformed it into something distinctly different from its cousins across the pond. The slated mansard, flat roofs, built-in gutters, and ornate cornices cannot be preserved and restored by the average roofer; one must possess extensive slate roofing, copper sheet metal, and carpentry skills. And the plan must be sensitive to the aesthetic to the style and with "in kind" materials.

Second Empire is an architectural style, most popular between 1865 and 1880, and so named for the "French" elements in vogue during the era of the Second French Empire. In a significant variation it is sometimes called the Napoleon III style. While a distinct style unto itself, some Second Empire styling cues, such as quoins, have an indirect relationship to the styles previously in vogue, Gothic Revival and Italianate eras. This style originated in Paris during the late 19th century. The second emperor, Louis-Napoleon, is not remembered for military prowess, but for the rebuilding of Paris into the City of Light--an impressive modern capital with grand boulevards lined by public monuments and town houses, all with mansard roofs. The nearly vertical roof form had been advanced in the seventeenth century by architect Francois Mansart and was embraced by the emperor's stylish consort, Eugenie.
In the United States, the Second Empire style usually combined a rectangular tower, or similar element, with a steep, but short, mansard roof; the roof being the quintessential defining characteristic of the style. This tower element could be of equal height as the highest floor, or could exceed the height of the rest of the structure by a story or two. The mansard roof crest was often topped with an iron trim, sometimes referred to as "cresting". In some cases, lightning rods were integrated into the cresting design, making the feature useful beyond its decorative features. Although still intact in some examples, often this original cresting has deteriorated and been removed. The exterior style could be expressed in either wood, brick or stone. More elaborate examples frequently featured paired columns as well as sculpted details around the doors, windows and dormers. The purpose of the ornamentation was to make the structure appear imposing, grand and expensive.

Floor plans for Second Empire residences could either be symmetrical, with the tower (or tower-like element) in the center, or asymmetrical, with the tower or tower-like element to one side. The style can be divided into five subtypes:

  • Simple mansard roof – about 20%
  • Centered wing or gable (with bays jutting out at either end)
  • Asymmetrical – about 20%
  • Central tower (incorporating a clock) – about 30%
  • Town house
The architect H.H. Richardson designed several of his early residences in the style, perhaps evidence of his French schooling. These projects include the Crowninshield House, in Boston Massachusetts, 1868, the H.H. Richardson House, on Staten Island, New York, 1868 and the William Dorsheimer House, in Buffalo, New York, 1868. In American Architecture, Leland M. Roth refers to the style as "Second Empire Baroque." Mullett-Smith terms it the "Second Empire or General Grant style" due to its popularity in building government buildings during the Grant administration.

The style was also used for commercial structures, and was often used when designing state institutions. Several psychiatric hospitals proved the style's adaptability to their size and functions. Prior to the construction of The Pentagon during the 1940s, the Second Empire-style Ohio State Asylum for the Insane in Columbus, Ohio was reported to be the largest building under one roof in the U.S., though the title may actually belong to Greystone Park Psychiatric Hospital, another Kirkbride Second Empire asylum. Second Empire was succeeded by the revival of the Queen Anne Styleand its sub-styles, which enjoyed great popularity until the beginning of the "Revival Era" in American architecture just before the end of the 19th century.
When focusing on the envelope of a structure, I believe that the use of traditional materials is at the core of sustainable design in historic preservation. That's why I founded the Traditional Roofing Network and went back to school for a M.Sc. in historic preservation at UMass-Amherst. I provide competent, thorough and appropriate direction and services to my clients. Guided by the Secretary of the Interior's standards for the rehabilitation of historic structures, we find that the use of traditional materials provides the foundation for preservation planning and building conservation. Working with historic homeowners and the stewards of landmark structures, I am committed to preserving the heritage of the region’s built environment. Whether its replacing the flashings on an historic slate roof, rebuilding copper-lined built-in gutters, or repointing the fa├žade of a 150 year old stone structure, I deliver quality and value to my clients.

There are very few firms in the northeast (New York and New England) with extensive expertise and a proven track record of correctly restoring Second Empire homes. From conditions assessment and project specification, to the execution of all phases of the restoration plan, all work and oversight is in-house. Contact us todayto discuss the preservation of your Second Empire home.



Early concrete masonry units in the United States

The advent of Portland cement in the United States after 1872 was a significant milestone in the history of our built environment. The entrepreneurial spirit that defined a nation was not spared when it came to the many uses and inventions that used cement. Concrete, mortar and block—the proprietary systems and materials that were developed and marketed were innumerable. This blog article will focus on the origins of modern construction’s concrete masonry unit (CMU.)

In the United States, concrete masonry units (which are also referred to as concrete block, cement block and foundation block) is a large, rectangular brick used in construction. These building blocks are made from concrete. The concrete is typically composed of Portland cement and aggregate, usually sand and fine gravel in high-density block. Lower density block may use aggregates that include industrial wastes, such as fly ash or cinders. From the historical use of such materials the term “cinder block” arose.  

The building and construction world were largely devoid of materials testing and code as we know them today. As the threat of fire influenced the drive toward “fire proof” construction, and large cities created code to protect life and property, the focus tended to be toward commercial, institutional and industrial construction. The realm of residential construction where concrete block was born was largely unregulated. Most testing was performed by the owners of proprietary products and systems as a part of their marketing strategy. Nevertheless, testing and standards (discussed later) evolved in the process.

Like most advances in technology, invention and creativity was driven by a profit motive. Foundations were typically constructed of stone, and built by stone masons. While the materials used were typically those indigenous to the region, few areas offered stone that was easily workable in a building capacity. From the granite boulders used in Boston cellars, to the bluestone used in the basements of Schenectady, working with stone is a laborious process performed by skilled men. Compare that to a similar tradesman of the late nineteenth century, the bricklayer. It is no coincidence that the International Union of Bricklayers and Allied Craftworkers provides separate designations for members who perform stone masonry and those who lay brick; and the bricklayers also lay the block.

Bricklayers erect masonry walls using relatively standard materials that are uniform in size. Brick manufacturing, by comparison to the quarrying and dressing of stone, is a relatively simple (and mobile) operation. Once the brick are ready for installation, little more must be done but to lay the brick level and straight between two plumb points. Block work on the same principles, but with much larger units. Foundation walls, for example, can be laid up rapidly, with much less labor and material, and conform with the ideals of standardized, modular construction that were firming up in the latter part of the nineteenth century. It is also easier to teach apprentices to lay brick and block than it easy to train stone masons.

Several companies, including Sears Roebuck and Montgomery Ward, sold machines that allowed the “average man” to make his own block. In essence, the machine was a stand with a form that the block material was packed into. A wide variety of shapes and sizes were available; one of the more popular plates allowed for the creation of ‘rock faced’ block that created the illusion of stone. The use of aggregate was wide and varied, and allowed for the use of cinders, giving rise to the term “cinder block.” Manuals instructed block makers to use greater portions of Portland cement toward the outer face of the block which would be exposed to the elements. Such a lack of standards often back fired, with negative consequences.

At this time, Sears and others were marketing kit homes in the United States. These machines, and the blocks they produced, became integral parts of many home packages. In fact, many kits were sold to make entire block houses. Many extant structures are still found from the turn of the century. Many homes and buildings (including a church in Hudson, NY, with a block arch) were erected with this system. An example that was proffered as an early successful use of the technology was the Allen G. Thurman house (ca. 1885) in Columbus, Ohio.

In addition to the materials used in manufacturing, the curing process was critical to the creation of good blocks. Only 50% strength was achieved after a week of curing, and a mere 65% at 30 days, yet testing took place at 28 days, as that was the approximate time in which they would be used. 95% strength is achieved after 6 months, and 100% was predicted at one year. The earliest testing methods were simple but effective.

The test of transverse strength measured the modulus of rupture on three blocks at 28 days. The average required was 150 pounds, with no single unit failing below 100 pounds. The compression test required an average strength of 1000 psi between the three units tested, with no single unit failing below 700 psi. The absorption test was calculated by measuring the percentage of absorption (weight of water absorbed, divided the weight of the dry sample.) The test was deemed a failure if the average absorption exceeded 15% or any single unit exceeded 22%. Later testing for freezing and against extreme heat was introduced, varying somewhat wider than the three relatively standard tests described.

The introduction of Portland cement in US building and trades after 1872 spurred technological advances in masonry greater than any the trade had seen in its millennia of history. That’s not as grand a claim as it might first appear when one considers how relatively similar masonry practices and materials remained up until the nineteenth century. Portland cement allowed for the creation of concrete, cement-based mortars and concrete block; these were masonry’s contributions to building technology as iron and steel allowed structures to grow taller and larger than ever before.


“Cinder block fire test,” Concrete. Vol. 21, No. 1, pp. 123-5. New York, 1922.
Concrete masonry unit, http://en.wikipedia.org/wiki/Concrete_masonry_unit

“Practical concrete block making,” by Charles Palliser, Industrial Publications Company. New York, 1908.
Concrete block, http://www.madehow.com/Volume-3/Concrete-Block.html

“Hollow concrete block building construction,” by Spencer Baird Newberry, Cement and Engineering News. Chicago, 1905.

The right man for the job: Finding (and hiring) the right contractor for the project

Surfing the web on a cold, wet March morning, I find myself amazed at how few articles or blogs cut through the fluff and filler of hiring a contractor to address a topic critical to the success of your next project: finding the right guy for the job! An item I don't see addressed at all is the importance of finding the right contractor for the project at hand. While it seems like an obvious statement to make, and a simple enough obstacle to overcome, it is the single-most important element to the success of the project and ultimate satisfaction of you, the consumer.

No contractor is a master of all skill sets in a given trade. Let's look at masonry as an example. There are some masonry outfits that do nothing but stamped concrete. Because it's all they do, they're set up for it: the tools, equipment and crews who are proficient in their craft. This allows them to offer a quality product at a competitive price. Now consider the mason whose company primarily builds block and brick walls for commercial customers on a regular basis. He may be able to successfully complete a stamped concrete 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'll be less 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, Philadelphia-style gutter on an old Colonial with a slate roof bring three trades into action: metal work, carpentry, and slate roofing. There are many carpenters who would find the copper-smithing and slate aspects of the job beyond their abilities. 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. He needs to demonstrate and prove himself through pictures, documentation and references for similar projects that he has 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 hundred-year-old trade manuals, the internet, and hands-on experience are the foundation on which a preservation worker basis 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.

While we're on topic some words of caution are in order. Make certain that he's licensed and insured, as your city and/or state may require. Some states, like Massachusetts and Rhode Island, require a construction supervisor's licensing or registration with the state contractors' board. This type of information is easily accessed through the internet. Make certain to call your town or city building department 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 any person is injured or property damaged during the job, it'll fall on your shoulders-you were the sneaky little devil who pulled the permit to save a few bucks. Most contractors who try this scam DO NOT have the insurances 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 insurances. General liability insurance for a MINIMUM $1 million personal injury and a MINIMUM $1 million property damage ARE NOT cost prohibitive for a restoration worker proposing to do high end work. A common scam many contractors run is to act like they have liability insurance, and that's good enough. Of equal or possibly greater importance is workers' comp. This one costs the big bucks and is what drives a legitimate contractor's prices up. 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 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.'

Following these simple guidelines will help you find the right outfit for your restoration project and get things moving in the right direction!
This article appeared in the Winter 2010 issue of 'Traditional Roofing Magazine'

Saturday, July 21, 2012

To point or not to point: How using the wrong mortar can actually harm historic masonry

We've all heard of home inspectors recommending that a chimney be repointed before the sale of a house, but what does that mean? Repoint... 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? Some that have little or no cement at all? And 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 neither Webster nor Oxford 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 that used on commercial construction sites to lay modern brick and block walls. It has lots and lots of Portland cement in it and probably differs 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 1820's during construction of the Erie Canal in upstate New York.)

The paradox of a masonry structure is that it's strength comes from it's 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 it 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% in the case of an ice cube. 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 on-line 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," "It'll take a couple years for it to blend in, if ever," or, worse, "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, they unwittingly call him back to ultimately rebuild the chimney that he destroyed!

Yes, that IS my real license plate!
A good repointing job should last at least thirty 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 mason contractor will not spend his free time forever going back and forth with you providing endless references and answering questions ad nauseum. 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 half a dozen references ready for a potential customer.

CONTACT US for more information by clicking here.

Adaptive Re-Use: Repurposing existing building stock

Adaptive reuse seeks to deal effectively with the issues of conservation and heritage policies. While old buildings may become unsuitable for their programmatic requirements, as progress in technology, politics and economics moves faster than the built environment, adaptive reuse comes in as a sustainable option for the reclamation of sites. In many situations, the types of buildings most likely to become subjects of adaptive reuse include: industrial buildings, as cities become gentrified and the process of manufacture moves away from city; political buildings, such as palaces and buildings which cannot support current and future visitors of the site; and community buildings such as churches or schools where the use has changed over time.

Adaptive reuse is seen as an effective way of reducing urban sprawl and environmental impact. By reusing an existing structure within a site, the energy required to create these spaces is lessened, as is the material waste that comes from destroying old sites and rebuilding using new materials. Through adaptive reuse old, unoccupied buildings can become suitable sites for many different types of use.
Criteria to Consider
While the process of adaptive reuse is a decision often made purely by companies establishing a particular brand or presence, there are often criteria for deciding whether a building should be conserved and reused or just demolished for the area of land it occupies. Some of these determining criteria include:

  • The societal value of a given site; that is the importance of the use of a site to the community or visitors’ use;
  • The potential for the reuse of a particular site; the physical damage sustained to the site and its support of future use, the character of the existing site in terms of the proposed reuse;
  • The historical importance of the site; in terms of both physicality of the street-scape and the area, as well as the site in the community’s understand of the past; and,
  • The natural ecological conditions of the site; whether the site is suitable climatically or can support the proposed environmental work needed in the site.
Advantages of Adaptive Reuse

With the debate of adaptive reuse as a sustainable avenue in the development of key sites, there are many advantages to using certain sites for redevelopment. Some of these advantages include the site’s location; in many cases, historical sites are often located in the centers of large cities due to the spatial development of a given area, these buildings can often be heritage-listed and therefore sold as an entity, rather than just for the land that they occupy, which the new tenants then have to retrofit the building for their particular purpose. Older buildings also often have a specific period character through the detailing and joinery of their constructed eras that newer or reconstructed developments lack, in certain cases, such as the hospitality industry; the grand character of a site can influence the feel of their building and are used for maximum potential to enhance the site’s physical attractiveness to a client.
Barriers to Adaptive Reuse

As mentioned above, adaptive reuse sometimes isn’t the most viable option for all historic sites. For some sites that have been left alone to decay by neglect, the physical damage of the site can render the site unusable both in terms of the cost to repair the damage as well as unsafe by government standards. Sites contaminated by old materials such as asbestos also become unviable for the process of adaptive reuse.
Providing Handicap Accessibility

Historically, most buildings and landscapes were not designed to be readily accessible for people with disabilities. In recent years, however, emphasis has been placed on preserving historically significant properties, and on making these properties-and the activities within them-more accessible to people with disabilities. With the passage of the Americans with Disabilities Act in 1990, access to properties open to the public is now a civil right. Modifications to historic properties to increase accessibility may be as simple as a small, inexpensive ramp to overcome one entrance step, or may involve changes to exterior and interior features.

A three-step approach is recommended to identify and implement accessibility modifications that will protect the integrity and historic character of historic properties:
1) Review the historical significance of the property and identify character-defining features;

2) Assess the property's existing and required level of accessibility; and,
3) Evaluate accessibility options within a preservation context.

It is a challenge to evaluate properties thoroughly, to identify the applicable accessibility requirements, to explore alternatives and to implement solutions that provide independent access and are consistent with accepted historic preservation standards. Solutions for accessibility should not destroy a property's significant materials, features and spaces, but should increase accessibility as much as possible.
Upgrade of Heating, Ventilating and Cooling Systems in Historic Buildings

The successful integration of new systems in historic buildings can be challenging. Meeting modern HVAC requirements for human comfort or installing controlled climates for museum collections or for the operation of complex computer equipment can result in both visual and physical damage to historic resources. Owners of historic buildings must be aware that the final result will involve balancing multiple needs; no perfect heating, ventilating, and air conditioning system exists. In undertaking changes to historic buildings, it is best to have the advice and input of trained professionals who can:
  • assess the condition of the historic building,
  • evaluate the significant elements that should be preserved or reused,
  • prioritize the preservation objectives,
  • understand the impact of new interior climate conditions on historic materials
  • integrate preservation with mechanical and code requirements,
  • maximize the advantages of various new or upgraded mechanical systems,
  • understand the visual and physical impact of various installations,
  • identify maintenance and monitoring requirements for new or upgraded systems, and,
  • plan for the future removal or replacement of the system.
Too often the presumed climate needs of the occupants or collections can be detrimental to the long-term preservation of the building. With a careful balance between the preservation needs of the building and the interior temperature and humidity needs of the occupants, a successful project can result.
Existing mechanical systems should be regularly inspected and maintained by a qualified HVAC contractor on a semi-annual basis. As plans are developed for the re-purposing of institutional structures, an upgrade to the mechanical system and addition of cooling may be considered. A mechanical systems engineering firm with a proven track record in historic structures must be consulted as the introduction of new systems in older buildings is not without problems--historic buildings are not easily adapted to house modern precision mechanical systems.

Careful planning must be provided early on to ensure that decisions made during the design and installation phases of a new system are appropriate. The size of the new system and needed output CANNOT be accurately calculated until AFTER improvements to the envelope (such as insulation an improvements to the fenestration) are accounted for. Since new mechanical and other related systems, such as electrical and fire suppression, can use up to 10% of a building's square footage and 30%-40% of an overall rehabilitation budget, decisions must be made in a systematic and coordinated manner. The installation of inappropriate mechanical systems may result in any or all of the following:
  • large sections of historic materials are removed to install or house new systems,
  • historic structural systems are weakened by carrying the weight of, and sustaining vibrations from, large equipment,
  • moisture introduced into the building as part of a new system migrates into historic materials and causes damage, including biodegradation, freeze/thaw action, and surface staining,
  • exterior cladding or interior finishes are stripped to install new vapor barriers and insulation,
  • historic finishes, features, and spaces are altered by dropped ceilings and boxed chases or by poorly located grilles, registers, and equipment,
  • systems that are too large or too small are installed before there is a clearly planned use or a new tenant,
For historic properties it is critical to understand what spaces, features, and finishes are historic in the building, what should be retained, and what the realistic heating, ventilating, and cooling needs are for the building, its occupants and its contents. A systematic approach, involving preservation planning, preservation design, and a follow-up program of monitoring and maintenance, can ensure that new systems are successfully added--or existing systems are suitably upgraded--while preserving the historic integrity of the building.

No set formula exists for determining what type of mechanical system is best for a specific building. Each building and its needs must be evaluated separately. Some buildings will be so significant that every effort must be made to protect the historic materials and systems in place with minimal intrusion from new systems. Some buildings will have museum collections that need special climate control. In such cases, curatorial needs must be considered--but not to the ultimate detriment of the historic building resource. Other buildings will be rehabilitated for commercial use. For them, a variety of systems might be acceptable, as long as significant spaces, features, and finishes are retained. Most mechanical systems require upgrading or replacement within 15-30 years due to wear and tear or the availability of improved technology. Therefore, historic buildings should not be greatly altered or otherwise sacrificed in an effort to meet short-term systems objectives.

Adaptive reuse seeks to deal effectively with the issues of conservation and heritage policies. While old buildings may become unsuitable for their programmatic requirements, as progress in technology, politics and economics moves faster than the built environment, adaptive reuse comes in as a sustainable option for the reclamation of sites. In many situations, the types of buildings most likely to become subjects of adaptive reuse include: industrial buildings, as cities become gentrified and the process of manufacture moves away from city; political buildings, such as palaces and buildings which cannot support current and future visitors of the site; and community buildings such as churches or schools where the use has changed over time.  CONTACT US  to discuss adaptively reusing existing building stock to meet your company or institution's program needs.