Tag Archives: architecture

Steps to Replacing Historic Wood Windows

QAHSC-landmarks-review-pmapdx Our first choice, and ethical preference, is to retain historic wood windows. Repaired and maintained wood windows constructed of old growth lumber will outlast any modern alternative. We advocate strongly for a process and philosophy that seriously evaluates retaining original material. The best approach compares long-term costs, embodied energy, and cultural importance relative to the same criteria for new replacement material.

But what do you do when the comparative process favors new material and replacement becomes the option of choice? And how do you gain jurisdictional and historic approval for removing character defining features from a historic property? Correct research, documentation, presentation, and material selection are the key factors to successfully replace historic wood windows.

Lack of maintenance is rarely accepted as a justifiable rationale for window replacement. Arguments for window replacement based on peeling paint, surface tracking of the wood, and/or glazing putty failure are typically countered with comments that benign neglect is a conscious act and straight forward maintenance will reverse the deterioration and deficiencies noted. A better strategy is to base replacement rational on existing significant deficiencies that require financial investment and resource allocation to repair the deficiencies.

QAHSC-landmarks-review-windows-pmapdx Most existing, older properties have had more than one owner. Research into original design documents, major rehabilitation projects, building permit requests, and other documents provide insight into processes that might have replaced original material. The removal and replacement of non-original material is justifiable and acceptable rationale.

Documentation by means of an on-site, window by window survey is the only method that will yield quantifiable data regarding the physical condition of existing wood windows. The resulting comparative data is critical for structuring an argument in favor of replacement. The field observations also provide invaluable information pertaining to the means and methods of construction and conversely deconstructing, or removing, the windows. Understanding wood window construction is important to understanding how wood window fail. Source documents like the Association of Preservation Technology’s Window Rehabilitation Guide for Historic Buildings (1997) and the National Park Service Preservation Briefs: 9, The Repair of Historic Wooden Windows provide exploded diagrams of both wood window construction and typical failure locations. These locations generally include the sash mortise and tenon joints, the exterior stops, and horizontal rails. The field assessment will need to document the quantity, location, and extent of any failed components.

QAHSC-landmarks-review-pmapdx After a thorough evaluation and understanding of the existing wood windows, the next decision is to choose a replacement product. In-kind replacement,(i.e. wood window for wood window; true divided lites for true divided lites, matching pane divisions, etc.) is preferred. When the replacement window is virtually identical to the historic window, it is hard to say no. Absent exact replacement, the visual qualities exhibited by the cross section profiles, the sash height and width, and the proportion of wood to glazing, are the most important attributes to match. Appearance from the exterior will trump appearance from the interior during a historic review approval process.

How the research findings, existing conditions, and replacement products are presented is fundamental to a successful request to replace historic wood windows. Agencies and commissions with jurisdictional review and approval authority require clear, methodical, and linear processes to understand the research, findings, and selection process. Collating the field data using charts and graphs, including graphic representation of previously altered windows, and defining the quantity of failed components will assist a decision in favor or replacement.

QAHSC-window-flashing-pmapdx When an opportunity to retain original fabric/windows is available, the opportunity should be incorporated into the work. Even retaining as little as 20% of historic fabric will increase the likelihood of approval for replacement of the remaining components. The retention of historic fabric also allows successive generations to better understand the history and changes of an existing property.

Written by Peter Meijer AIA, NCARB, Principal.

Inherent Sustainability of Historic Architecture

Trinty-Episcopal-Church-pmapdx

The terms ‘Sustainability’, ‘Green Building’, ‘Environmental Design’, and other similar phrases have recently become critical in how we approach and understand contemporary architecture. As concerns over pollution, global warming, and our impact on the surrounding environment have gained traction – we have begun to understand the building industry’s contribution to these issues. The US Green Building Council reports that buildings account for 39% of all carbon emissions in the United States, surpassing both industry and transportation.

At the core of the issue is how architects, clients, and the public imagine buildings should function and operate; a vision which has transformed over the last two centuries as technological advances have developed the capabilities of the building industry. In the last two centuries, buildings have become monuments to the Industrial and Technological Revolutions. The development of electrification, central heating, air conditioning, steel and concrete have transformed how architects design and how users function within the built environment. This shift has transformed architecture from an inherently sustainable practice into a much more complex and often unresponsive process.

While the phrase ‘sustainability’ has only recently been associated with architecture, many historic buildings were designed by incorporating sustainable practices. Without electricity, buildings by necessity had to respond to site orientation and the local climate. Natural ventilation was used to passively cool buildings, well placed windows provided natural light, and construction methods varied by location to provide an appropriate level of protection from the surrounding environment. However, as a result of modern renovations, these sustainable attributes are not always utilized to their fullest potential.

Historically, large, operable windows were an integral component of architecture in moderate climates like the Pacific Northwest. The glazing provided natural daylight while the operability allowed users to ventilate spaces based on thermal comfort. Today, the operability of windows in many historic buildings has been compromised for a variety of reasons:

• Windows that have been fixed shut to prevent users from overriding the central air system.
• Broken window hardware that hasn’t been properly maintained.
• Windows that have been painted shut.
• Windows that have been fixed shut to minimize maintenance.

Without the natural ventilation that was incorporated into the original design, these historic structures often overheat and/or rely heavily on central air conditioning. One must question why the inherent sustainability of these historic structures was compromised. Was it simply our initial infatuation with mechanical heating/cooling systems? As passive sustainable design gains traction it is critical that we understand the capabilities of historic structures in regards to their inherent sustainability.

For further investigation we have identified a case study that explores the possible impact reintegrating natural ventilation may have on thermal comfort. Trinity Episcopal Cathedral in Portland, Oregon was built in 1906 and the original design included 10 operable dormers along the Sanctuary roof. The dormers have since been boarded over, preventing rising heat from escaping. Congregants find the space overheated during the summer months and one must question whether operable dormers would provide adequate ventilation to sufficiently cool the space.

An energy model has been developed using OpenStudio and EnergyPlus to compare the thermal comfort of occupants within the space. A baseline model mimics the existing conditions and provides a comparison for the two different natural ventilation configurations. One natural ventilation configuration re-introduces the operable roof dormers to vent hot rising air. The other natural ventilation configuration re-introduces the operable roof dormers and integrates additional ventilation at the exterior wall of the building to produce stack ventilation.
Trinity Results-wufi-pmapdx

While the project is still in process, initial results indicate that natural ventilation could have a significant impact on the space. The study has focused on the thermal comfort within the Sanctuary and results show that natural ventilation could dramatically lower indoor temperatures during peak summer months.

Trinity Results-wufi-pmapdx

Trinity Results-wufi-pmapdx

The results continue to be fine-tuned, and further refinement of the energy model will include:

• Adjusting schedules/systems to more closely reflect the building’s occupancy.
• More accurately defining the exterior infiltration rates.
• Exploring more relevant solutions for integrating stack ventilation that don’t require the large operable exterior windows. For example integrating ventilation through the basement into the main sanctuary.

While further research remains to be done, initial results are promising and demonstrate the inherent sustainability of the structure. While each building is unique, this Case Study shows how reintegration of natural ventilation may be a viable solution for passive cooling in uncomfortably warm historic buildings. Continue to check back for updates as we refine our study and explore how re-integration of natural ventilation may result in energy savings!

Written by Halla Hoffer, Architect I

Towards a Death of Architecture

Buildings are physical representations of the social, economic, political, technological, and cultural climates of their eras of origin. Ultimately buildings represent our cultural heritage and our architectural history. However, mid-century modern era buildings are increasingly interpreted as antiquated architecture that is functionally obsolete and lacking use in today’s society. Our recent-past modern buildings are being labeled as “failed” or “useless” architecture. As a result, mid-century modern architecture is rapidly being demolished and replaced with newer sustainable structures believed to better represent our most current social and cultural ideals. Current architecture is believed to be far more aesthetically pleasing than their modern predecessors.
But in the context of society, including heritage, what constitutes “useful” architecture verses useless building? There must be a relationship of parts to complete the building, but structure and function alone do not equate to architecture. Perhaps “useful” should be a term connected to architecture exhibiting enduring design excellence? Paradoxically, design excellence is tangled with style, and history demonstrates that style preference is ephemeral, subjective, and fluxuates at a high velocity. Yet the loss of style preference, or the falling out of design aesthetics favor, is one of the biggest rationale for the demolition of modern era buildings. Presently, Brutalism is at the crux of the demolition/ preservation debate.

Framed in the context of history, it can only follow that Brutalist buildings were going to be executed as formal monumental concrete structures that directly juxtapose (even challenge) their environments. But more often than not, the perspective of historic context is outnumbered by present aesthetic preference. For example, Prentice Women’s Hospital (Bertrand Goldberg) in Chicago, the Berkeley Art Museum (Mario Ciampi) in California, and several of Paul Rudolph’s brute beauties were technological and architectural triumphs of their time. However, the Brutalist buildings like other modern era buildings that rate low on the aesthetic-scale have been equally disregarded in their maintenance. The argument for demolition based on deficiencies caused by a lack of maintenance becomes all too convenient. The wide-spread demise of brutalist civic and urban buildings is a demise of the ideologies
behind the intent of the architecture and those housed within.

Aesthetics cannot be the pretext for significance or the preservation of architecture. Letting aesthetics judge value will strip our architectural history of some of the most influential and innovated examples of modern era architecture. In effect, we are killing, and ultimately denying claim to, a portion of our architectural history. There is value in the perspective of context and value in re-using and re-imagining modern era architecture. If aesthetic preference continues to get in the way, what use is there for the architect or an architectural legacy?

Written by Kate Kearney, Marketing Coordinator

When A Master Work Fails: Three Case Studies

Some of the greatest restoration challenges arise when historically significant works weather, degrade, are neglected, or simply have suffered through inappropriate renovations. Restoration strategies are compounded when original historic materials, either natural materials like wood or stone, or production processes are no longer available. And when the failure is due to improper design or inadequate construction methods, corrective restoration methods may alter or compromise the original design intent. The following three case studies illustrate restoration philosophies based on balancing preservation, resolving the underlying building deficiencies, and introducing “thoughtful change” in protecting significant local structures for future generations.
John Yeon 2012 004
Case Study 1
John Yeon’s 1948 Portland Visitors Centerwas designed as an exhibition showroom with large open spaces, a pinwheel plan, on a highway dividing median, accessible by car, and constructed of standardized wood framing components including recently developed experimental plywood. When the highway was replaced with a riverfront park and the Visitor Center programming was relocated, the singular purpose building became obsolete resulting in a number of incompatible conversions including substantial alteration of the main gallery space to an industrial kitchen. Contributing to the slow demise was the degradation of the exterior wood components and failure of the plywood as a result of the northwest climate and inadequate weather protection. By the time the Friends of John Yeon and the City of Portland Water Bureau invested resources into the restoration, the Visitor Center had lost or compromised 80% of its historic interior finishes and the exterior façade had been heavily altered. However, the original floor plan, massing, scale, exterior spaces, and essence of Yeon’s modular design and sense of place remained.
WS Scheme 3 Entrance 101209 Space programming respected the historic floor plan and scale of the original structure and recreated Yeon’s original design intent of integrating indoor space with outdoor space. Extraneous equipment and unsympathetic additions were removed from both the interior and exterior. Interior design elements, furniture, and fixtures maintain the open gallery spacial quality while integrating new furniture and fixtures meeting the needs of the tenant. Major preservation focused on the exterior restoring original paint colors through serration studies, restoring building signage in original type style and design, preserving original wood windows, when present, and restoring the intimate courtyard with a restored operating water feature.

Case Study 2
120907 Lovejoy Pavillion 002 Moore, Lyndon, Turnbull & Whitaker’s 1965 Pavilion at Lawrence Halprin’s Lovejoy Fountain is a whimsical all wood structure with a copper shingle roof. Although a small structure, the pavilion represents a major mid-transitional work for Charles Moore as his design style moved from mid-century modern to Post-modern design. In keeping with the naturalistic design aesthetic established by Halprin, northwest wood species comprise the major structural system including the roof trusses, vertical post supports, and vertical cribs built from 2 x 4 members laid on their side and stacked.

Vertical loads are transferred from the trusses to the wood posts and spread to the wood cribs. Under the point loading, the cribs have compressed resulting in a sag or lean in the roof structure. Since the 2 x 4 wood members have crushed, they cannot be restored or salvaged as part of the restoration effort so new members were designed to replace the historic material.

120907 Lovejoy Pavillion 009 The restoration approach is intended to correct the structural deficiencies and replace the failed members with no changes to the historic appearance of the structure. The crib design allows for insertion of new steel elements, invisible from the exterior, capable of providing additional support for vertical loads. The difficulty arises because standard wood products available today have different visible and strength attributes from standard components available in 1965. Sourcing appropriate lumber is dependent upon clear and quantifiable specification, high quality inspection, and visual qualities. There are no structural standards for reclaimed or recycled lumber compounding the incorporation of “old growth” lumber as part of a new structural system. When original source material is no longer available, best practices for narrowing the selection of new materials will of necessity be combined with subjective visual qualities and a best-guess scenario as to how the new material will age in place similarly to the historic material. There are no single solutions so experience is key.

PMAPDX-survey-city-of-portland Case Study 3
Whether or not Michael Graves’ Portland Building is considered a master work is greatly debated. Never the less, the building was nominated to the National Register of Historic Places after only 30 years and is recognizable around the world as THE building representing the start of Post Modernism. There is no debate to the fact that the building leaks. However, the method of building envelope repair could dramatically or minimally impact the exterior character defining features.

The façade of the Portland Building incorporates standardized aluminum single unit windows, aluminum windows ganged together to form a curtain wall, ceramic tile, and stucco veneer as the prominent construction materials. All of these systems or individual components are neither produced nor assembled currently in similar manners due to improvements in technology and building envelope science.

Proposals to improve envelop performance of both the individual window units and window systems are challenged in finding products that will both improve performance and retain the aesthetics of a Post Modern building. (i.e. retain the essence of criticism towards Post Modernism by preserving the appearance of insubstantial material installed as a thin veneer). Windows have always been a source of controversy in preservation and now the definition of windows has expanded to include curtain wall systems as the importance of preserving Recent Past and Modernism has entered into the mainstream.

When a structure, like the Portland Building, relies heavily on the expression of its skin as the character defining feature, off the shelf solutions for fixing envelop deficiencies must be expanded to include customization, façade impact studies, robust strategies for solving the issue, and out-of-the-box thinking by conservators, architects, historic consultants, and building envelope experts. A collaborative approach based on the original architect’s design intent must drive the decision making. It is an unusual approach, but original design intent will be a key factor when resolving façade problems on Modern and Post Modern structures.

Written by Peter Meijer AIA,NCARB, Principal
portlandbuilding-model

Washington Park Reservoirs

With the Portland City Council’s final decision not to further delay projects to build new reservoirs to replace the five historic open reservoirs, on the west side of the city in Washington Park a new below grade water storage tank is being planned in the general footprint of one reservoir. The second of the two reservoirs at Washington Park will be decommissioned and used for new purposes. The implementation of underground storage tanks may still elicit a spirited discussion. And at the heart of the discussion is how to implement thoughtful change to a historic, well loved cultural resource to the rigors of rapidly evolving public safety and seismic protection mandates.
WA Park Reservoirs
Reservoirs 3 and 4
Reservoirs 3 and 4 were constructed as part of the Bull Run water system, a gravity-fed mountain watershed system built between 1894 and 1911 to provide the City of Portland with high quality drinking water. Reservoirs 3 and 4 continue to function as the city’s primary water distribution source for the west side of Portland. The reservoirs have been in continuous operation for more than 100 years. They serve as a featured amenity enriching the landscape of Washington Park, one of Portland’s largest and oldest parks, with vistas of open water, and period historic structures. Also due to their location on hills on the west side of the city, scenic views are afforded across the reservoir water.

As summarized in the National Register of Historic Places nomination, “one of the most defining landscape principle of Reservoirs 3 and 4 is the open expanse of water, their irregular shape, rusticated concrete structures, and ornate wrought iron detailing of fences and lampposts. The reservoirs are a striking and elegant addition to the serene forest that makes up this end of Washington Park. The surrounding forest is composed primarily of Douglas fir, western red cedar, and big leaf maple all predominating native tree species of the Pacific Northwest.”
Historic 1894 photo of WA Park Reservoir 3
The Design Challenge
The challenge is to design a 100 year plus engineering solution while simultaneously designing a thoughtful change to the context, natural park setting, and historic district. Arising from the Olmsted Brothers vision for Portland and the City Beautiful movement, the changes to the Reservoirs offer an opportunity to evaluate the evolution of development outside Washington Park within the Park, changes to the Reservoirs themselves, public access, and protection of cultural amenities. If access to the “water” is transformed to a public amenity, how does the design enhance the serene qualities of the site? How should the change reconnect the reservoir area with the surrounding neighborhood and Park features?

WA Park ZOO circa 1900 The reservoirs embody the challenge associated with retaining a historic place as both a visual element and a dynamic landscape. The safety, security and seismic solutions may alter the purpose of the visual feature and the interaction with the “water,” but that does not translate into a diminishing of a historic place. There are no easy answers. In the end, this final decision should be assuring that the Washington Park Reservoirs will continue to provide safe, reliable water storage, and to elicit wonder well beyond the next 100 years.

Written by Kristen Minor, Preservation Planner

Preserving an Icon

Under the leadership of the Pittock Mansion Society, Portland Parks & Recreation, and hundreds of volunteers, the venerable Pittock Mansion is undergoing the first phase of preservation activities in anticipation of the Mansion’s Centennial celebration. Built for Henry Pittock, an Oregon pioneer, newspaper editor, publisher, and wood and paper magnate, “the Pittock Mansion occupies a place of special importance for Portland. It is a City of Portland Historic Landmark, a State of Oregon Landmark, and a national landmark listed in the National Register of Historic Places. The City of Portland owns many historic landmark properties, but Pittock Mansion is the only [property] operated as a historic museum [within] the city parks system.” (Historic Structures Report, 1st Edition, A Staehli, 1984)
Pittock Mansion Site Observations
After successfully raising funds, and with City Council approval of additional funding, the Pittock Mansion is repairing the exterior terraces with new waterproofing membranes, new sandstone replacing inappropriate concrete castings, and structurally reinforcing the baluster railings so that all the brides and grooms, admirers, and visitors, can once again perch and pose with the vista of Portland and Mt. Hood as the splendor of Pittock Mansion is in front of them.

“Pittock Mansion was design in 1909 by Edward T. Foulkes and took five years to complete. Georgiana Pittock, wife of Henry, died in 1918, having lived in the house for only four years. Despite its prominent site, imposing French Renaissances exterior, formal rooms and parlors, and impressive central hall with a grand stairway, Pittock Mansion was fundamentally a home for a family with modest tastes having lived most of their lives in undistinguished Victorian houses in downtown Portland.” (Historic Structures Report, 1st Edition, A Staehli, 1984)
Pittock Mansion Terrace Repair PMAPDX
Original stone quarries are no longer operational, so an exhaustive search for replacement stone was conducted finalizing in a selection of stone from Idaho closely matching color and texture of the original. Local and regional craftsman are again involved in the careful dismantling, numbering, cleaning, fabrication, and re-installation of the stone details. New terrace tile, selected to better match the variegated colored clay tile roof, will be installed with a new waterproof membrane and improved flashing details. The original glass “sidewalk” purple lights that admit light into the basement will remain for all to enjoy.

Histoirc photo Pittock Mansion There is still much work to be done. The Pittock Mansion Society has identified the top priority projects ranging from the practical structural and electrical work to additional programming and preservation projects. The Centennial celebration will be a grand formal affair, fitting for such a magnificent and unique cultural icon within the City of Portland’s stewardship.

Written by, Peter Meijer AIA,NCARB, Principal

Preserving the Modern in St. Louis

St. Louis, MO is home to several architectural gems from the mid-century modern era. The city recently conducted a property survey of over 2,000 non-residential buildings constructed between 1945 and 1970. The Cultural Resource Office of St. Louis is highlighting a selective survey & inventory of 200 significant properties with input from PMA and the public to help develope a master list of 25 of the most significant mid-century modern masterpieces. Surveying these architecturally significant structures gives a voice to a past era that still directly influences today. St. Louis’s built heritage from the mid-century modern era showcases structures from internationally recognized architects that revolutionized architecture and design throughout the 20th century.

A Legacy of Modern Architectural Design
The post-World War II era in the United States led to the development of the Modern Movement Architecture across urban areas. Contributing factors of this development included the impact of the auto industry on the built environment, a more cost-conscious public and government, and several technological advances. In addition to these factors, St. Louis was home to the prestigious school of architecture at Washington University. The school had diverse and international students and teachers that contributed to some of the most prolific designs of modern architecture.

When discussing St. Louis mid-century modern architectural design three architects stand out: W.A. Sarmiento, Gyo Obata, and Minoru Yamasaki. Their designs were sleek, yet whimsical, and made St. Louis globally recognized for its modern architectural designs.

W.A. Sarmiento design

W.A. Sarmiento is an internationally regarded architect who designed some of the most prolific buildings in the city of St. Louis. A native of Peru, Sarmiento began as a draftsman for Oscar Niemeyer. In 1952 he accepted a position with the Bank Building & Equipment Corporation. From 1952 through 1964, Sarmiento revolutionized the design and function of banking facilities. Ten years after working for the Bank Building & Equipment Corporation, Sarmiento left after J.B. Gander’s death and formed his own company. W.A. Sarmiento Architects expanded to included offices in St. Louis, Phoenix, and San Francisco. Sarmiento closed his practice in 1978 and left behind a legacy of modern architectural design including the saved American Automobile Association (AAA) Building (1976), the Chancery of the Archdiocese of St. Louis (1962), and the Jefferson Bank and Trust Building (1955).

St. Louis Science Center James S. McDonnell Planetarium (1963

The St. Louis Science Center James S. McDonnell Planetarium (1963), was designed by the local firm of Hellmuth, Obata, & Kassabaum (HOK), with Obata as lead designer. HOK was founded in 1955, and to this day is a global leader in architectural design. The practice began by designing schools in suburbs of St. Louis, and by the 1960s it a grown and began to open offices nationally, with their first international branch opening in 1984. Obata was the lead designer of the Saint Louis Science Center along with other notable St. Louis buildings. The building has a visually striking and expressive shape, somewhat reminiscent of a nuclear power plant tower. It is a thin concrete shell structure, hyperboloid in section. This architectural design is a premiere example of continuous contemporary design.

Lambert International Airport

Minoru Yamasaki’s domed design for Lambert’s main terminal became the forerunner of modern terminal building plans. In 1951, the firm of Hellmuth, Yamasaki, and Leinweber was commissioned to design and update the Lambert- St. Louis Municipal Airport. In 1956, their design was the first building in St. Louis to receive a National AIA Honor award. This building was originally composed of three vaults, with a forth added in 1965. Yamasaki’s design became a model for a new generation of airport terminals. Eero Saarinen’s designs for the TWA terminal at John F. Kennedy Airport in New York, and the Dulles Washington Airport terminal both echo the repetitive concrete vaults of Lambert St. Louis Municipal Airport.

STL MODERN logo PMAPDX For more information about this exciting project, including a list of buildings for intensive research, mid-century modern properties, city map with property locations, and property descriptions. Visit: Mid-Century Modern Survey

Written by Kate Kearney, Marketing Coordinator

Horizontal Ground Motion: A Call for More Seismic Research

There is a lack of significant research and seismic performance studies on the resiliency and inherent strength redundancy of older buildings.

U.S. Post Office & Courthouse, 7th &; Mission Streets, SF

In specific, the capacity of existing buildings to resist ground motion associated with earthquakes has not been fully developed or thoroughly researched. Based on damage from earthquakes, especially the 2010 Canterbury and 2011 Christchurch earthquakes in New Zealand, with additional seismic activity lasting nearly one year, the general thought is that older existing buildings perform poorly in response to ground motion. When analyzed further, the damage from the Christchurch earthquake was predominantly due to acceleration in a vertical direction, literally tossing buildings in to the air. The peak vertical acceleration during the Christchurch earthquake exceeded the design criteria for today’s modern buildings. Not lessening the severity of the event, nor proposing for less stringent seismic codes, the Christchurch earthquake would flatten most modern cities regardless of building age. Adequate resistance to vertical movement cannot be achieved with current engineering techniques and therefore research and performance studies regarding the resiliency of existing structures must concentrate on horizontal ground motion.

1906 earthquake, Montgomery Street block, SF

Because little can be done to prevent building collapse during vertical motion, seismic strengthening techniques focusing on dampening and resisting horizontal motion are applicable to existing structures as well as new structures. However, there has not been significant studies documenting and establishing the inherent strength to resist horizontal motion due to redundancy and mass of archaic construction methodologies. Independent performance evaluations of unique structures have occurred in the United State, Italy, Mexico, the Baltic, and others regions around the world without formal comparative analysis of the results or thorough in-depth dissemination and publication of the studies. For instance, in Oregon, informal static shear testing of a circa 1925 public middle school’s interior fire block and plaster wall surprised structural engineers when the walls did not crack at the shear planes (i.e. floor and ceiling connections) and strength measurements exceeded code allowance fivefold. (2001 Portland Public Schools shear test) When calculated and tested, the ½ inch chalk boards added even more in-plane horizontal resistive strength. The result of the testing saved the school district approximately $ 1 million in seismic upgrade costs. There was no formal documentation of the result and there has been no known similar testing performed on other existing school properties.
mosque

The seismic resistance of existing structures is affected by the structural typology, the construction materials, the varying modifications, and deterioration and decay of materials over time resulting in unique conditions that are not readily transferrable to other structures. However, sporadic investigation and research performed on existing structures and published by the international RILEM Technical Committee 20 TBS in the article “Specific recommendations for the in situ load testing of dwellings and of public and industrial building structures,” and published accounts of independent studies in journals such as the Association of Preservation Technology Bulletin offer insight into the potential redundant strength capacity of existing structures to resist horizontal ground motion.

full scale shake table These studies combined with documented field assessments and field evidence of older structures surviving earthquakes and repeated ground motion disturbances over several hundred years are available in numerous communities and offer case study structures for further research. The numbers of university engineering departments with “shake tables” (e.g. Portland State University) create opportunities for joint partnership with private sector consultants, public agencies, and professional organizations to assess and analyze the unique aspects of archaic building materials and methodologies for seismic response. The collaboration between university and private cooperation for seismic research has the potential to develop a wealth of practical and applicable information. The current collaborative efforts involving energy consumption offer the model from which to base seismic research.

A development of systematic research, publication, and dissemination of the inherent strength of existing structures to resist horizontal ground motion would benefit all communities across the globe.

Written by Peter Meijer AIA, NCARB, Principal

Historic Preservation and New Construction in Historic Districts

Historic Districts are not frozen in time.
Ideally, Districts are busy, vital places where people live, work, socialize, and see community values reflected. Typically, buildings contribute to a district and share common characteristics becoming more historically valuable as a group than as individual properties. If we create, restore, and invest in Historic Districts, the Districts will continue to tell a story about a particular time period, a particular community, or perhaps a particular industry. So is new construction appropriate within a Historic District, and if so, how does one properly design and integrate the new building within the existing historic context? This posting will explore some factors and opinions on new construction in Historic Districts.
PMAPDX OSU Buildable Landarea
Some individuals argue that appropriate infill must be visually identical to nearby historic resources. Most architects in practice today have a condescending reaction against recreating previous styles as making “faux” or “Disneyland” architecture, even though western architecture for hundreds of years has recycled various stylistic revivals. It is not an absurd concept to design and build beautiful, high-quality buildings that reflect an older style and method of construction. Other individuals have no trouble placing a contemporary structure next to older structures, since modern buildings have a responsibility to reflect our shared culture and lifestyle.

Neither of these absolutes works for most situations. New buildings, as stated in the Secretary of the Interior Standards, do need to be “differentiated” from contributing buildings in a District to avoid a false sense of history. The question is how much differentiation is required? Though there are cases where a “missing tooth” in a very cohesive pattern of buildings should be constructed to resemble its historic neighbors, in other cases the visual diversity of architectural styles and periods within a District allows for more flexibility in differentiating new buildings. Historic Districts are listed on the National Register because they possess a concentration of buildings that are linked either historically, aesthetically, or both. One Historic District might represent a fairly large span of time, various architectural types and styles, and a number of different uses. Another District might be much more specific in its focus.

Opsis Architecture for OSU

As Preservationists and Architects, we need to analyze the characteristics and contexts that are the same and the characteristics and contexts that are different about the resources within the District. Each case is unique and site-dependent. It is possible to allow for stylistic additions and change without showcasing the change; to temper the inclination to design an individually iconic building; and to limit a modern “intrusion” so as to respect and highlight the older buildings. Good design, high-quality detailing, and high quality materials contribute towards compatibility, and adaptive reuse and change is inevitable to the vitality of a Historic District.

Each jurisdiction having authority makes its own interpretation of what it means to be compatible. One recent example is an approval by the Historic Resources Commission (HRC) in Corvallis, Oregon. The Corvallis HRC approved a design for a freestanding metal and glass canopy in the heart of the national registered Oregon State University Historic District. The HRC concluded that there was no historic precedent for a freestanding non-building element, but found that the canopy was visually light and well-designed and fit into the open space pattern of development without detracting from the neighboring Contributing resources. The role of the historic consultant in this case was to construct an argument as to why the canopy was compatible in the District, and push back against earlier suggestions that the canopy become more “building-like” with masonry columns. An open structure with a veneer of building material would have created a less compatible design.

Opsis Architecture Canopy design for OSU

Each proposal for new construction in a Historic District should be informed by its context. There is latitude for new construction to be distinct, as long as the new work does not detract from the surrounding historic resources.

Written by Kristen Minor, Preservation Planner

Burnt Clay Facades

Terra cotta, or “burnt clay,” is a hard baked, high grade of weathered or aged clay. It is similar to brick but the clay is of higher quality and fired at higher temperatures. This article focuses on exterior architectural terra cotta as distinguished from statuary, pottery , and terra cotta blocks used as inner wythes of wall or fill material.
300px-Court_of_Honor_and_Grand_Basin
The 1893 Columbian Exposition in Chicago demonstrated the versatility and ornamental qualities of terra cotta. It highlighted the great variance in color and shapes possible with terra cotta and began the demand in the United States for terra cotta that lasted through the late 1930s. Terra cotta is prized for its light weight, longevity, aesthetic qualities, and unit construction. At the peak of production, almost every urban area in America was producing architectural terra cotta in some variation. Today, most replacement units are produced by either Gladding McBean or Boston Valley Terra Cotta.

Specific forming techniques including hand press, machine press, slip casting, and extrusion are used depending on the shape and style of unit required. In the analysis of terra cotta failure the forming techniques are less critical than the strength characteristics of the fired clay, the integrity of the exterior surfaces, and structural support systems.
Boston Valley new TC
Exterior ornamental terra cotta was marketed as a light weight water proof cladding. And if proper construction techniques were employed, and the system was maintained, and the local climates were mild, terra cotta performed as sold. However, terra cotta adorns buildings in severe weather climates, and is installed with structural materials affected by environmental conditions, and located on façade elements inaccessible for routine maintenance.

The mortar joints are the material most susceptible to failure. Joints often exist on all three axis with some units of terra cotta designed for flat horizontal surfaces. Over time and exposure, the mortar fails providing a means for water intrusion. Sever cycling of weather in simultaneous freeze/thaw conditions can cause the terra cotta clay to expand and contract, accelerating the crazing or cracking of the protective glaze. Extensive crazing can lead to glaze spalling and allow for further water intrusion.

Once water enters the system there is no weep path allowing for water egress. Construction means and methods, as well as the cellular unit design, trap water and contribute to the potential corrosion of steel lintels, wire ties, steel structural support members, and other miscellaneous metals. Rapid freezing and thawing cycles, in addition to steel corrosion, can crack terra cotta units. If the units remain unrepaired, further water intrusion and/or absorption will occur.
121022 QAHS S Elev 094
The repair of terra cotta will depend both on the cause and manifestation of the defect. Typical defects include crazing of the glazed finish, shallow surface spalls, deep spalls affecting the bisque, cracked units, inadequate support and / or anchorage, corrosion induced stress fractures, impact damage, mortar degradation, lack of maintenance, and inadequate repairs.

Proper terra cotta repair methods are linked to the cause of defect. Repair techniques are often performed on-site by skilled tradesmen. When damage to the terra cotta unit is severe, full replacement may be required. Defects due to inadequate support or a result of corrosion to supporting steel members is likely to require more invasive repair strategies including removal and replacement of several courses of interlocked terra cotta units.

QAHSC When replacement units are not required and the scope is limited to on-site repair, labor costs exceed material costs. Since many historic terra cotta units were specialty designed and installed for the structure, a premium price is paid for replacement. New exterior decorative terra cotta is available only from the sources referenced and with small quantity orders, the first unit is approximately $5,000 with much of the costs attributed to making the form and determining the finish color and texture. Subsequent costs per unit will decrease with the range of decrease dependent upon quantities required.

The most important component of terra cotta repair is an understanding the cause of deterioration and the proper repair specifications. Both are derived after a full condition assessment and evaluation of the existing conditions.

Written by Peter Meijer AIA, NCARB, Principal

——————–
Sources
• Last of the Handmade Buildings, Virginia Guest Ferriday, Mark Publishing Co., Portland, OR 1984
• National Park Service, Preservation Brief No7, Preservation of Glazed Terra Cotta
• APT Pacific NW Chapter 2005 workshop
• Terra Cotta, Standard Construction, Revised Ed., National Terra Cotta Society, 1927