Dealing with snow and ice dams in traditional roof systems

By mid-January of 2015 it seemed like Mother Nature had forgotten to deliver winter to those of us in the Northeast.  Over the next four weeks, however, Boston and other parts of New England experienced record-breaking snowfalls that would challenge season-long records in a single month.  And, with these extreme conditions, has come ice damming, water intrusion and threatening snow loads the likes of which had never been seen.

As this graphic demonstrates, ice damming occurs when heat loss causes snow to melt and slide down the slope of the roof.  As it reaches the part of the roof over the soffit, it freezes because there is no heat loss occurring.  The result is a buildup of ice that makes it increasingly difficult for melt water to escape as the ice grows in height.  The problem may be exacerbated by gutters which are clogged or don’t drain properly and, in essence, form an icy shelf on which the ice dam may grow.

Once the melt water begins to pool up it will wick back under the roof covering materials and into the building.  Ice dams must be removed without damaging the roof covering materials.  This may involve hand tools, chipping guns and steaming equipment.  The ice dams may be so extensive that the best and/or most cost effective approach is to open channels in the dams and coat the ice with calcium chloride to accelerate the melting process. 

Once this winter is over, countless home and building owners will want to make improvements and alterations to prevent future ice damming and water intrusion.  The first, and simplest measure, is to make sure that gutters, outlets, conductor pipes, and drainage inlets at grade are free and clear of obstructions.  Next, look at the way the building is insulated.  The addition of fiberglass insulation between roof rafters or the attic floor joists will make a huge improvement.  The use of closed-cell, spray foam insulation should be resisted (see http://traditional-building.com/Ward_Hamilton/?p=379for more information.)

More involved measures are also available.  The use of heating coils or, “heat tape,” is often employed to keep the snow and ice over the soffit melted and the snow melt water flowing.  If you want to investigate this method further, seek and obtain quotes from three firms that specialize in these systems.  Products sold at home improvement centers, designed to be installed by the purchaser, may have trouble keeping up with even normal snowfalls.  Seek out “commercial grade,” industrial-strength systems installed by professionals, even for residential applications.

Another option is the installation of snow slides, or snow “pans,” over the soffit.  Commonly made of copper sheet metal, they form a virtually impermeable layer that ice has trouble bonding with.  While less expensive materials like galvanized steel may be used, the short term savings should be weighed against the long-term cost when the lesser metal outlives its useful service life and must be replaced.  These systems are commonly seen in Upstate New York and Vermont, and seen less frequently in other regions of the Northeastern and Mid-Atlantic states.        

Because of a general lack of insulation in their roofs, ice damming is not uncommon in older buildings. The problems that they can cause when water infiltration damages interior finishes necessitates removal and, where possible, prevention.  Care must be taken to remove the snow and ice safely and without damaging roof covering materials, gutters and cornices.  By keeping gutters clean and clear, and adding insulation, much of the cause of the ice dams may be mitigated.  Installation of heat tape and snow pans will further reduce the chances of ice dams from forming but are not inexpensive.  Always consult with an experienced, traditional building professional before undertaking such a project.

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“Nobody is telling me what color I can paint my house!”

The creation of local historic districts, and the subsequent enforcement of historic preservation laws, creates a special set of challenges for preservation planners.  Buildings and structures on the National Register of Historic Places are afforded little—if any—protection against inappropriate alterations or even demolition.  Protection comes on the municipal level when towns and cities adopt a bylaw or ordinance such as MGL Chapter 40C Massachusetts Historic Districts Act or similar statutes in other jurisdictions.  Once a city or town adopts the law they can move toward the creation of local historic districts (LHD) that are governed by an historic district commission (HDC.)

Getting property owners to agree to an LHD is a daunting challenge, no doubt. Culturally, we're programmed to resist and question any infringement of our rights by government, especially the suggestion of someone telling us what we can or cannot do with our property.  And HDCs are government entities telling people what they can and cannot do with their properties.  We cannot ignore that fact—it must be dealt with head on.  There is a statement that could be made to the building owners within proposed LHDs everywhere:  "This isn't about you—we know you'll do the right thing—it’s about what someone else might do some day."  This appeals to the building owner because you're mitigating any concern that the purpose of the LHD is to tell him what he can or can't do. 

And you're planting the seed of concern: "What happens when the people next door sell some day and the new owner wants to do something hideous to the façade of the house?" Or, what happens when the new owner of the charming block of stores next to your business wants to knock it down and build a new Dunkin’ Donuts? Isn't that the purpose anyway, to prevent the wrong thing from happening in the future, not correcting or changing existing conditions?  Theoretically, the building and home owners in these areas like old houses and structures and appreciate the charm and character that they possess.  Hopefully they also understand and appreciate the economic value this adds to properties in their neighborhood.  Build on that. 

Public perception of historic districts and commissions appears to be the greatest hurdle preservation planners have to overcome when creating and overseeing LHDs.  How often have we heard the rally cry, “Nobody is telling me what color I can paint my house!” yet HDCs generally don’t dictate color choices. The best way to counter such myths and misconceptions is through transparency of actions and clear, wide-reaching communication to the public.  The internet is good vehicle for communicating that process.  Every LHD needs design guidelines and the Town of Brookline has an exemplar:

http://www.brooklinema.gov/index.php?option=com_content&view=article&id=342&Itemid=510

The Historical Commission in the Town of Ipswich has a website that should be closely studied:

http://www.historicipswich.org/

The home page of the Ipswich website is a one-stop directory to all of the resources and information that home and building owners need to access.  It is also an engaging site that pulls the viewer in with great pictures and wonderful local history as well as pertinent, contemporary information.  The charm and value of antiquity is present here and viewers are compelled to buy into it.  Increasing public awareness of historic preservation is the best way to increase public appreciation of historic preservation.  Click HERE for an article on this very subject.  Selling people on the importance of historic preservation is critical, as even old home enthusiasts can occasionally be recalcitrant in their support.

Our society is pretty good at accepting the need for zoning laws, permits and building code, but somehow restrictions due to historic preservation send folks over the edge.  Why?  Once a building is protected within an LHD it can’t be inappropriately altered or demolished.  That's the law.  Period. Don't like it? Sell it and move on.  Better yet, why buy a property in an LHD in the first place? The mindset that an owner should be able to do whatever he wants with a building simply because "he owns it" is ridiculous.

Should he be able to hire an unlicensed, uninsured contractor to throw together a set of ramshackle stairs without a permit? Why not? He owns it.  

Should he be able to make changes and alterations that violate code? Why not? He owns it. 

Should he be able to dump toxic waste in the basement? Why not? He owns it. 

Can he pile as many tenants inside as he wants, and provide one crummy toilet and no fire protection? Why not? He owns it.

Just because you own a house or other building doesn’t mean the law be damned, like it or not.  Saying a building owner should be able to do whatever they want with their building is tantamount to saying that one should be able to mistreat a pet--because they own it--or burn money because they can. Anyone who thinks that way shouldn't be allowed to have a pet or doesn't deserve to be rich. Same goes for historically significant buildings. The fact that one fails to recognize, appreciate and respect that significance is neither here nor there. It is illegal to abuse your dog or destroy US currency. And it’s illegal to alter or demolish a building in an LHD without HDC approval.

Photo credits:  Carole Osterink, The Gossips of Rivertown, except the historic photo of the Upper Depot in Hudson, NY, credited to City of Hudson Historian Pat Fenoff and the contemporary image of the same building taken by international photographer Lynn Davis.

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.

---

[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/

Appropriate Roofing Material Choices for Historic Structures

Selecting a historically appropriate roofing material is often restrictive as a simple matter of economy. Not everyone can afford a new slate roof. But individually landmarked structures and those in local historic districts are often monitored by historic district commissions (HDCs) that often 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.

Cultural Heritage and the Challenge of Sustainability

Historic Preservation Lecture Series

UMass Historic Preservation Program
Second Symposium on Preservation and Sustainability

“Cultural Heritage and the Challenge of Sustainability”

Sponsored by:

University of Massachusetts-Amherst
Department of Architecture + Design
Public History Program/Department of History
Department of Environmental Conservation: Building Construction, & Technology
The UMASS/Hancock Shaker Village Historic Preservation Program

When: Friday, March 01, 2013 from 1:00 PM – 5:30 PM
Where: University of Massachusetts-Amherst, Lincoln Campus Center, Room 165
Admission: Open to the public (See below if seeking AIA credits)

Symposium Goals:
This symposium will explore the challenges of preserving cultural and historic resources in an era of climate change and the additional challenge of bringing sustainability to these sites. Each presentation will be followed by a short question and answer period.

Welcome and Introduction:
Max Page, Ph.D., Professor of Architecture and History and Director Historic Preservation Program, UMASS-Amherst

Keynote Speaker:
Diane Barthel-Bouchier (SUNY-Stony Brook)
Cultural heritage and the Challenge of Sustainability — a global view of how cultural heritage is responding to the climate crisis and the challenge of sustainable development.

Case Studies:
Ethan Carr (UMass-Amherst, Landscape Architecture/Regional Planning)
The Sustainable Historic Site: Martin Van Buren and Lindenwald — a description and analysis of a conservation–based plan to transform the landscape of this presidential homestead.

David Glassberg (UMass-Amherst, History);
“Sustainability and Landscape Character on Cape Cod?” An examination of Cape Cod historic resources and the effects climate change may have and the effort to quantify the effect of climate change on historical and cultural resources.

Carey Clouse (UMass-Amherst, LARP and Architecture + Design)
“Farming Havana: Preserving Urban Agriculture Landscapes for Food Security”
This session will highlight the progressive urban food landscapes in Havana, Cuba, while addressing the role of open space preservation and conservation in the larger context of food security and environmental stewardship.

Chris Skelly (Massachusetts Historical Commission)
Preservation and Sustainability: Policy and Practice in Massachusetts. Skelly, the head of local programs for the Massachusetts Historical Commission, will offer examples of effective projects and policies in Massachusetts’ communities.

Directions & Parking

For directions and maps: http://www.umass.edu/visitorsctr/Directions_to_Campus/
Parking: parking is available at the Campus Center garage (for a fee).

Learning Units
For all architects, learning units can be earned by attending this or any of the WMAIA monthly programs. For more information regarding learning units, contact Lorin Starr at director@wmaia.org

Cost:
$50 for those seeking AIA Learning Units. (Note, this program is free and open to the public, however, please register with WMAIA and submit the administrative fee if you want WMAIA to record Learning Units (LU’s)

For those non-students who are not seeking AIA credit, a donation of $10 is suggested.
 

How does slate roofing perform in a hurricane?

Bad weather is coming.  Very bad weather.  Winds, driving rain—the stuff that makes us pause and lok up at the roof.  How does slate hold up compared to other material choices?  The American Society of Testing on Material has established a standard specification for roofing slate, C-406, which tests the slate for three physical requirements that the slate must pass to be classified as an S-1 to 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.

After being crushed by hurricanes in the early 1990’s and seeing staggering losses from sub-standard building practices and materials, the government in Miami, Florida, decided to do something about it.  New standards, testing and licensing were created by legislators that raised the bar higher than anywhere else in the United States. In order to have your product “Miami-Dade-County “ approved the product must pass many stringent tests.

This includes the wind up-lift test where the slate was tested on a roof and subjected to 110 mph wind 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 rain fell.  The result?  No water penetration was detected underneath afterward.  This testing is by far the most severe for roofing products to pass and only clay tile materials could come close to the performance of slate.