Is Greener Always Better? Problematic Use of Modern Materials in Traditional Building Systems

When new words and terminology enter our vernacular, they often take on a connotation larger and broader than they deserve.  Today, “green” and “sustainable” are synonymous with responsible living and construction, their meanings understood as clearly by an architect or engineer as they are by the lay person.  They are buzz words that make consumers feel good about their purchases; they’re doing their part to protect the environment and help save the world.  But, in certain applications, use of these terms is more than a misnomer; it’s outright false advertising.

Technological advances in building science have allowed for the creation of the most energy efficient systems and materials that the construction industry has ever seen.  With the ever rising cost of every fuel type, energy conservation is always a high priority when planning for and designing buildings.  Buildings, historically, are only as efficient as the technology of the day allowed.  While we may shudder with the chill of a stiff breeze standing by the window in an 1885 Queen Anne Victorian, imagine the relative level of comfort that one of the Pilgrims would have enjoyed in the same situation!

Today’s building designers want to create watertight, airtight structures that use minimal amounts of energy with windows sealed tight and year-round climate control for maximum comfort.  They strive to design an envelope that needs low or no maintenance, fully accepting that building owners will not care for their buildings as a given.  As far as new construction goes, there’s no problem.  In fact, this is good news.  But what happens when the owners of older buildings want to implement these new technologies to increase the efficiency of their buildings?

Older building stock tends to be far less efficient than modern buildings.  Wall systems and joinery, windows and doors—they’re just not as tight.  An unexpected benefit of these inefficiencies is the passive ventilation that occurs, be it laterally through windows, doors and walls, or by the “stack effect” in which warm air rises, bringing vapor with it, escaping through the uninsulated roof system.  Know this: older buildings breath.  Modern building systems are designed so that structures don’t breath and vapor is removed with dehumidifiers or other mechanical forms of ventilation.

In older buildings, solid masonry walls rely on the temperature gradient between interior conditioned spaces and the outside for walls to drain properly.  Insulating these walls stops or mitigates the passage heat through the solid brick masonry.  This slows the drainage/drying process and traps moisture vapor in the wall which, during freeze-thaw cycles, freezes and expands up to 12% in volume.  Oftentimes the result is damage to the wall system of the envelope.  Instead, the focus should be on controlling moisture and preventing it from entering the wall system, both inside and out.

Today, older buildings have kitchens, bathrooms and laundry spaces that they didn’t when first built.  This introduces a significant amount of moisture vapor that may enter the wall system from the interior.  Installation of a vapor barrier will prevent this from occurring without impacting the thermal effect that heated interior spaces have on the exterior walls.  Outside, mortar joints must be kept tight and full.  Penetrations such as window and door jambs must be sealed tight where they abut masonry to prevent water intrusion. 

Roof drainage systems must be functional; gutters protect and shed the walls from runoff and properly placed leaders direct the rainwater away from the building at grade.  It’s also interesting to note that many older masonry buildings have large windows resulting in a high window opening-to-wall surface area ratio.  Improving the efficiency of the fenestration through conservation and repair, as well as the addition of efficient interior or exterior storm windows, will help preserve the historic integrity of the building while also saving on energy costs.

Recently a client contacted me with questions and concerns about insulating his masonry walls.  He was engaged in gutting much of the interior space in his circa 1870 brick townhouse in a National Register historic district in Boston’s South End.  The building department was demanding that he insulate behind the walls in compliance with the International Energy Conservation Code.  When we pointed out that the code specifically exempts buildings on or eligible for inclusion on state or national historic registers, he said it didn’t matter if there was a lot of interior gutting; that was his interpretation of the code.  Only later, when a staff member from the Boston Landmarks Commission intervened, was he straightened out.

Before you breath a sigh of relief, owners may have to prove that their historic projects are worthy of exemptions from the International Energy Conservation Code following changes to the forthcoming 2015 version approved by the International Code Council last year.  The changes were proposed by representatives from the New Buildings Institute, the Natural Resources Defense Council and the Institute for Market Transformation and they remove the exemption language from the code. The group added a requirement that permit applicants file a report with a code official when seeking immunity on specific areas of their project.

Do they sound like groups that know about old buildings?  No, they don’t.  They sound like groups that think LEED certification matters when it comes to old buildings; you know, organizations that don’t think full life cycle analysis matters in “green” building practices.  Why wouldn’t the team include representatives from the Association for Preservation Technology or the Preservation Trades Network?  And, frighteningly, who will train the code official that decides whether a project receives an exemption or not?  The answer is NOBODY.  So guess what happens when you encounter our friend in Boston?

More and more I’m coming to believe that these people actually hate old buildings.  I’ve had arguments with architects and contractors who wanted to spray closed-cell foam insulation between the rafters under slate roofs.  Some specified removing all the slate and covering the roof with an ice and water shield membrane then reinstalling the slate, effectively “sealing” the roof tight.  Besides being an unnecessary, exorbitant extra cost, there’s a big problem with these grand, USGBC-inspired plans:  they actually destroy the materials in a traditional roofing system.

Slate, clay tiles and wood shingles are traditionally fastened to battens, skip sheathing or regular old boards—not plywood, no underlayments.  The roofs are water tight, not air tight and the building breaths through the roof.  Fiberglass insulation can improve energy efficiency and reduce heat loss without preventing the roof from breathing.  Additionally, soffit and ridge ventilation can be added if desired.  Traditional roof materials like slate, clay tile and cedar shingles experience condensation.  The passage of vapor helps dry things out.  When you stop the roof from breathing everything stays wet.

Slate is comprised of thin layers of metamorphic rock that delaminate and fall apart when they are kept damp for months.  Clay tiles, like terra cotta and brick, will disintegrate.  Wood shingles rot.  Steel fasteners will experience corrosion and fail.  This has been the end of many a slate roof; I’ve pulled the slates off the roof and seen it with my own eyes.  Cedar shingle roofs will last five years, max, when installed on a solid roof deck covered in ice and water shield.  The reality is this: greener is not always better, especially when wielded by those unfamiliar with traditional building systems.  “The greenest building is the one already there” is a common expression in the historic preservation world yet it’s never heard in “green building” circles.  Go figure.       

When do building materials turn into historic fabric?

Historic fabric is a term used regularly in the historic preservation world but what it is or—better—how it comes to be, receives disproportionately little attention. McGraw-Hill’s Dictionary of Architecture and Construction defines historic fabric as “those portions of a building fabric that are of historic significance.”[1]  This definition implies that materials that are part of a building develop significance, presumably over time and as it relates to the life of the building.  One might also infer from the definition that some parts of a building may not possess historic significance.  What other sources provide a definition for historic fabric?  It would be ideal to point to a definition supplied in the Secretary of the Interior’s Standards for the Treatment of Historic Properties but one does not exist.  Surprised?  There’s no definition of historic fabric in the National Park Service’s Cultural Resources Management Guideline’s glossary either.

The Secretary’s Standards do address significance, however, as it relates to tangible things like cornices and columns and they identify four strategies for effectively dealing with historic buildings: preservation, rehabilitation, restoration, and reconstruction.  The first approach, preservation, is the most desirable and “places a high premium on the retention of all historic fabric through conservation, maintenance and repair.” Further: “It reflects a building's continuum over time, through successive occupancies, and the respectful changes and alterations that are made.”[2] Changes to a building, such as a mansard roof added to an Italianate or so-called Victorian details added to a brick building in the Federal style, are an accepted part of its record and how it’s evolved over time.

However, exactly where and when old alterations or changes to a building develop significance and become historic fabric is not clearly defined for us by the Standards.  And, if “respectful changes and alterations” are to be preserved, why have we decided that the continuum has stopped and we are resistant to additional changes and alterations? Indeed, a great deal of attention has been focused on how to create historically appropriate additions to existing buildings—make it like the original, but easily distinguishable, and smaller in scale. But what about a 1920s rear ell on a Greek Revival? If it looks “right” we want to save it but, if it doesn’t resonate with our collective sense of taste and what we think it should look like—if it doesn’t look “right”—then we’re receptive to wholesale alteration or even demolition.

In my experience as a contractor and consultant I have appeared before numerous historic district commissions throughout New York and New England. This has afforded me the opportunity to listen in as applicants for certificates of appropriateness make their pitch for permission to replace windows, change facades or roofing materials, and otherwise destroy historic fabric. The part I’ve always found most fascinating is when the element or system the applicant wants to demolish is part of the “respectful changes and alterations” that have been made over time. If the alterations are respectful, as the Secretary’s Guidelines indicate, the commission will fight hard to protect them. If not, approval is often swift and paves the way for the demo crew. Does respectful mean it ‘looks right’?

Respectful is a relatively subjective term and, as it applies to a discussion about the value, significance or integrity of an architectural detail, more subjective still. Merriam-Webster defines respectful as “marked by or showing respect or deference.” So, do respectful changes and alterations show deference to the original building? Perhaps not in style (reference the earlier examples of the Italianate and the Federal-style buildings with juxtaposed styles as major alterations) but in the quality of the craftsmanship and the materials used? The dictionary’s definition of deference as “a way of behaving that shows respect for … something” is of little help. Unhelpful, that is, unless we view the term esoterically and, in this context, meaning that the newer work is of a quality and standard worthy of standing beside the original.

That would be a convenient conclusion, if not for the fact that the historic preservation world possesses a general aversion to the idea of altering historic buildings, and this inference would seem to indicate that new alterations and changes can be viewed as acceptable if the quality of work is very high. Returning to the “building's continuum over time” issue, one might think that worthwhile, respectful alterations and changes ceased by the beginning of the twentieth century or perhaps as late as the 1930s when sun porches were vogue additions atop single story bump-outs at the rear of nineteenth century homes. Adding a Second Empire mansard roof to an Italianate, or Victorian details to a brick Georgian, are a clear mishmash of styles that, if proposed today, would be unacceptable.

Is that because the changes, dramatic as they were 150 years ago, are now deemed respectful because they, too, are ancient and reverent? This smacks of Ruskin: “When we build let us think we build forever ... that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our fathers did for us.’”[3] There is something special about a hand-planed molding, a carved stone capital, or a centuries-old brick wall—and we treat them with reverence out of respect for the quality of craftsmanship and materials that have endured the test of time. The tangible item that is ancient is automatically awarded respect and shown deference because it is old, and as Ruskin would indicate, becomes sacred. Modifications and alterations to the building, no matter how dramatic they may have been then, are acceptable now and protected.  

Circle back to the earlier question: Exactly when do alterations or changes to a building become historic fabric? Imagine if the owner of the Italianate sought a certificate of appropriateness to remove the mansard roof and restore the building to its original style. His application would undoubtedly be rejected. But what if there was an addition on the side of the building from 1900; would it be considered historic fabric? Why or why not? Since we’re dealing with subjective terms, and varying views, perhaps it depends less on the materials and craftsmanship than one might think. Some historic district commissioners may be patently against demolition and, as such, the “continuum over time … respect for changes” argument is well-suited. Still, even staunch preservationists have a breaking point; some changes must be unacceptable and worthy of the landfill.

Wherever that line lies, on the other side is the place where building materials turn into historic fabric.

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[1] McGraw-Hill. Dictionary of Architecture and Construction, (2003)

[2] Weeks, Kay D., and Grimmer, Anne E. Secretary of the Interior’s Standards for the Treatment of Historic Properties, (1995) 

[3] Ruskin, John. The Seven Lamps of Architecture, (1849)

All photos courtesy Carole Osterink http://gossipsofrivertown.blogspot.com/

Traditional building materials: Still the best choice for #historicpreservation

 

While the internet may be a fantastic tool for sharing information, we must realize that good advice is transmitted as easily as bad.  Consider this recent dialogue from a historic preservation message board in New England.  An architect asked, “Has anyone had experience with use of cellular PVC to ‘replicate’ architectural details on a historic building?”

 
While the respondents were quick to cry nay! for that use, I was surprised by how many suggested that there are permissive uses of PVC composites. In fact, the chairman of a historical commission near Boston indicated that they had adopted a policy of allowing cellular PVC in place of ground-contact lumber (like bottom step risers and porch skirt boards) and rooftop balustrades (if traditional profiles are duplicated) in their local historic districts.

I was shocked.

In the limited instances where wood-meets-earth or the worst precipitation (window sills, balustrades and stair treads), PVC composites may appear to be an attractive alternative. But its use should be considered with caution; new composite risers, fascia plates and sills will not show signs of degradation, but they will conceal what's happening to wooden structural members behind them.  So, when it fails, be prepared for wholesale failure of the system.  ("Gee, the stairs looked great ... who knew the stringers were rotted?")

Like many issues in restoration work, this one can be attributed to a lack of informed sources.  The building owner typically knows only as much as the contractor has told them.  PVC composites are widely available and spend a tremendous amount of money "educating" would-be consumers through marketing. Consider the Secretary of the Interior's position on the subject:

"If repair by stabilization, consolidation, and conservation proves inadequate, the next level of intervention involves the limited replacement in kind of extensively deteriorated or missing parts of features when there are surviving prototypes (for example, brackets, dentils, steps, plaster, or portions of slate or tile roofing). The replacement material needs to match the old both physically and visually, i.e., wood with wood, etc. Thus, with the exception of hidden structural reinforcement and new mechanical system components, substitute materials are not appropriate in the treatment Preservation."[1] (Underlining added for emphasis)  

The use of PVC composites is an attempt to cut corners and remove maintenance and upkeep from the equation.  Consider the use of Spanish cedar, mahogany, oak, and other hardwoods in these limited applications.  You may be surprised how close the price is to the composite materials.

Photo credits:  Three accompanying photos, all courtesy of the author, depicting the finials that will be replicated in the millwork shop for the author’s upcoming project at Historic New England’s ‘Roseland Cottage’ in Woodstock, Connecticut.

 

 

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[1] Standards for Preservation and Guidelines for Preserving Historic Buildings

(http://www.cr.nps.gov/hps/tps/standguide/preserve/preserve_approach.htm)

Be Prepared: Maintenance plans for historic structures

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."[1]

The most important component of any plan to preserve a historic structure is maintenance.  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 a property owner or manager creates a maintenance program for their building, it is strongly recommended that they seek the counsel of a preservation consultant, and/or experienced contractor. 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:

·         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;

·         An emergency list of contractors who can be called upon in an emergency, especially HVAC, electrician, plumber, and roofer;

·         Individualized procedures for the historically appropriate handling of the individual systems and materials of the building; and,

·         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 of the structure.

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, schedule inspections, and guide the work necessary to for a historic building. When a property owner or manager creates a maintenance program for their building, it is strongly recommended that they seek the counsel of a preservation consultant, and/or experienced contractor. The maintenance program should clearly identify and describe courses of action that are specific to the building. When the full life cycle of a building is considered, there is no smarter money spent than on maintenance.

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[1] National Park Service, Nationwide Programmatic Agreement Toolkit for  Section 106 of the National Historic Preservation Act, glossary of terms