Category Archives: Blog

Future Trends for Architectural Conservation

As part of the sesquicentennial celebration of Canadian Confederation independence, the National Trust for Canada and the Association for Preservation Technology International co-sponsored the largest joint conference of heritage professionals. Over 1,100 attendees from twenty countries attended the week-long event focused both on technical issues and heritage planning.

The shear size of the conference was overwhelming, but the host city, Ottawa, (APTI) was an ideal venue because of its position as the capitol city of Canada, the quantity of heritage resources, including the Rideau Canal World Heritage Site, and beautiful world class museums and parks.

As with all APTI annual conferences, the week begins with two day long workshops highlighting the craft of preservation. This year’s workshops included Logs & Timbers, Masonry Mortars, and Digital Tools for Documentation. Masonry Mortars has been offered several times over the last five years at APTI conferences and is always popular demonstrating the continual need to understand mass masonry walls, their performance, and specialized products and skills required to restore and preserve the walls.
PMAPDX-APT-2017-Conference-002
How Robots Can Assist with Conservation
National Trust conferences, in both Canada and the United States offer many tours during the course of the conference and one of tours focused on robotics for heritage conservation. A conservation lab at Carlton University, founded after World War II and one of Ottawa’s public universities, has created a curriculum around the use of robotics to enhance the preservation craft of traditional materials. Conference attendees viewed a demonstration of a robotic arm manufactured in Germany, by the supplier of robotic arms to the automotive industry, with a custom built “hand” designed to hold stone cutting tools. As a demonstration, the Carlton University staff carved a block of sandstone scheduled to replace original material on the Canadian parliament buildings as part of a massive restoration effort. The demonstration was fascinating in the speed by which the robot carved the material with fine accuracy. Attendees were interested in the conservation aspect of the robot and asked about the stone cutting techniques and potential replacement of stone carvers.

Since the robot uses circular drill bits as cutting tools resulting in smoother finishes than traditional chisel cutting, some attendees were skeptical of the robot as a tool for capturing traditional stone techniques. As to the replacement of stone carvers, the response was straight forward: there are fewer and fewer trades personnel that know how to carve stone. The robot is envisioned as a method to allow traditional stone decoration to return to modern design.
PMAPDX-APT-2017-Conference-001
With seven separate tracks of Paper Sessions, it was impossible to take in the full offerings of the joint conference. The use of robots, technology, and computer software simulations continued throughout some of tracks of the Paper Sessions. Particularly interesting was hearing from archeologists in Italy and Chile that, unlike US archeologists, are involved in the documentation, history, and preservation of building materials. Using traditional archeological approaches to documentation and recordation, the archeologists combined their research, historic photographs, current images, on-site destructive testing in unique ways of explaining the chronology of construction and materials used.

Demonstrating the continued convergence of building envelop science with preservation science, many Paper Sessions focused on windows, energy retrofits, and the need to develop better science and research of traditional construction means and methods. One session on mass masonry walls hypothesized that mass masonry walls have a temperature ductility allowing them to expand during cold wet weather in order to accommodate the stress induced by freezing temperatures. One early study in the 1960’s documented the phenomena but without sufficient repeated testing. The engineer making the presentation asked for all those in the audience to create an accessible database of masonry performance in order to expand the collective knowledge base.
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The Future of Preservation Looks Modern
One of the plenary speakers called on heritage preservation to continue leadership in the adaptive reuse of existing buildings, specifically mid-century modern structures, because of the huge environmental impact conservation efforts will have on global warming, waste reduction, and heritage values.

Attendance at APTI national conferences are a great way to gain new knowledge, converse with professional peers, anticipate future trends, evaluate current business practices, and interact outside day to day professional demands.


Written by Peter Meijer, AIA, NCARB / Principal

Analysis: Best Practices for Providing Effective Daylight in Mid-Century Modern Structures.

DOCOMOMO_OREGON and the Northwest Chapter of the Association for Preservation Technology recently held an Energy Conservation Symposium that explored issues facing mid-century modern buildings: How can modern historic buildings comply with today’s energy conservation standards? Is it possible to maintain the integrity of the historic building materials and aesthetics while also meeting new energy conservation requirements?

At PMA we believe that while challenging, it is possible to maintain the integrity of these historic mid-century modern buildings and meet new energy conservation requirements. In an effort to explore this possibility, we submitted an abstract for the symposium, and Halla Hoffer, AIA, subsequently presented on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures.
on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures


Background
Effective daylighting can reduce both lighting and cooling loads while improving user comfort, satisfaction, and health. Despite plentiful glass, using daylight in mid-century modern building can be challenging. Glare and uneven light distribution can cause user discomfort and pose challenges to effectively daylighting spaces. Frequently, artificial lighting is used to balance lighting in spaces over lit by the sun, negating any potential energy savings. For existing buildings, the available methods to provide effective daylighting are limited by the existing constructions and configuration. To both preserve existing structures and provide ample daylight a critical question must be answered – what are the best practices for improving daylight in existing buildings? This study provides insight to daylighting existing structures, specifically, how light can be controlled and distributed in mid-century modern buildings with plentiful glazing.

1963 Residential Tower
This study explores and analyzes how common daylighting strategies can be implemented on existing mid-century modern structures. The study focuses on a sixteen-story 1963 residential tower in Portland, Oregon, and explores how interior reflectivity, interior/exterior light shelves, shading, and glazing can impact daylight availability and distribution. The study looks at a variety of ways each strategy can be implemented and analyzes the results to determine best practices based on daylight distribution/availability, glare, lighting loads, and heating/cooling loads.
on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

Tools Used for the Specifics of Analysis
Emerging tools and technologies provide effective methods of analyzing hundreds of different daylighting simulations. Applications such as Grasshopper and Dynamo, which are visual programming environments for Rhinoceros 3D and Revit respectively, allow users to explore a variety of different design interventions and determine optimal solutions. Prior to starting the daylight analysis, we began with a “base geometry” of the existing conditions that we modeled in Rhinoceros 3D. We then developed a Grasshopper file to create daylighting interventions. For this study the interventions consisted of interior light shelves and exterior shading devices based on numerical inputs for shelf depth and height. Using Grasshopper in lieu of traditional 3D modeling allowed us to systematically test multiple variations of intervention geometry. In addition to studying how new geometries would impact daylighting we also studied how existing/new materials could impact daylighting performance.
on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

The daylighting analysis was performed using DIVA for Rhino, a plug-in that performs daylighting and energy analysis directly in Rhino. DIVA also offers several Grasshopper nodes, allowing the analysis to be controlled and managed directly in Grasshopper. For this analysis the primary results we extracted and used to measure performance included:

  • Annual Daylight: Percentage of time space receives at least 300 lux. This value can be mapped over the area under analysis. Typically, areas that receive 300 lux at least 50% of the time have the potential for daylighting.
  • Spatial Daylight Autonomy (sDA): Percentage of a space that receives 300 lux for at least 50% of the annual occupied hours. This metric provides a single number for quickly determining daylight potential. A value over 55 indicates that daylighting will be at a minimum nominally accepted by occupants. A value over 75 denotes a space where daylighting will likely be preferred by occupants.
  • Annual Sunlight Exposure (ASE): Percentage of a space that receives over 1,000 lux for at least 250 hours per year. High values indicate that the space may be overlit and cause glare/discomfort.
  • Daylight Factor: A ratio comparing light levels on the interior of the structure to the light levels on the exterior. Typically, a value under 2% indicates that the space cannot be adequately daylit, a value between 2%-5% is preferred for daylighting, and a value over 5% indicates that the space is well daylight, but may be overlit.
  • on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

    Conclusions
    Reflective interior surfaces can have a significant impact on daylight distribution.

    Without any shading there is a high probability for glare according to ASE and DF values.

    Interior light shelves alone can reduce the ASE values and the probability of glare.

    Interior light shelves alone are not as effective as exterior shading devices in reducing glare.

    A combination of reflective interior materials, interior light shelves, and exterior shading devices is the most effective method to provide adequate levels and even distribution of light.


    Written and presented by Halla Hoffer, AIA, Associate

    Assessing a Historic House in Springfield, Oregon

    Owning, maintaining, and providing active use within a single family settlement era house is not a typical mission for a public parks agency. One such property is the Reynold & Eva Briggs House located in the northeast corner of the Dorris Ranch Living History Farm, in Springfield, Oregon, currently stewarded by Willamalane Parks and Recreation District (WPRD). Compounding the unusual situation is that the area is a historic site, a working farm, and a public park. In addition the property’s history, age, material, and conditions of the house add further complexity to the stewardship role. In order to guide the WPRD with long-range decisions regarding the Briggs House, the District sought an up to date exterior and interior condition assessment and potential rehabilitation options in support of current and future park programming needs, including as a source of income derived from continued residential use. The Briggs House has not been occupied since its last resident left in 2009.
    Briggs-House

    The Assessment
    The property, The Dorris Ranch Living History Farm, was listed as a National Register of Historic Places Historic District on June 22, 1988. While the Briggs House is located on the ranch property, it sits outside the boundaries of the historic district.

    As researched by University of Oregon historic preservation students, the settlement era house is one of the five oldest houses in the Springfield area and one of the city’s few remaining examples of box construction from the Homestead era. The oldest portion of the house—the two-story volume and its eastern wing—was originally constructed by George Thurston in 1872, and later served as the home of caretakers Reynold and Eva Briggs. Once vernacular in the Willamette Valley, the house exhibits a Gothic-influenced upright-and-wing style of construction and was expanded in the 1890’s to accommodate the changing needs of its residents.

    Typical of early homestead sites, the Briggs House was constructed without a foundation. The original substructure that continues to support the house consists of partially hewn wood posts on stone piers set directly on the ground surface. Utilizing the box-construction method, 1-inch by 11-inch boards were set vertically and connected to the 7-inch by 9-inch sill plate and ledger plate above the posts to create a “box” form without the use of other framing members. Two-inch by 4-inch roof rafters were then set above the top ledger plates. Floor joists, the original board-and-battens wall siding, and roof panels were added to the house after its basic skeletal structure had been completed. The original wall siding was replaced with weatherboards at an unknown date. Portions of this siding were later replaced with shiplap in the 1890’s, and the entire exterior was later covered with T-111 siding in the 1970’s.
    Briggs-House

    The Rehabilitation Challenges
    After discussing the main program activities that take place on Dorris Ranch with Willamalane Parks and Recreation District staff, PMA recognized the primary challenge to any rehabilitation options was the balance between maintaining the historic character of the house and meeting all the code requirements mandated by a rehabilitation, including public access, universal access, and mechanical, electrical, energy, and plumbing upgrades. Previous studies undertaken by Restore Oregon on similar settlement era houses indicated that a balance must be reached between preserving the essence of the house while changing and modifying other portions of the house and property to achieve programming needs. Complicating the Briggs House options are siting of the house within an active area of the park, the two story volume, the lack of an adequate structural foundation, and accommodating large classroom needs within original tiny floor plans. Every room of the historic property has an established spatial function and are tiny in size. Any rehabilitation option must consider that all rooms in the house would be “flexible” and be used as needed for a variety of purposes.

    The Potential Role of Historic Status
    Willamalane Parks and Recreation District currently stewards the Briggs House as a historic property by maintaining and protecting the property from encroachment by nature, animal and pest infestation, and unsafe use by park visitors. Inclusion of the property within the district as a contributing resource has both pro and con impacts. Inclusion within an expanded boundary of the current National Register Dorris Ranch Historic District could prove beneficial in finding financial sources to help with a rehabilitation although the available funds are likely insignificant when evaluated against the full cost required to upgrade the Briggs house to a public structure. On the other hand, including the property in the district may prove problematic for WPRD as it may limit, or make more difficult, viable and creative rehabilitation options that would not be approved by the local jurisdiction having authority.
    Briggs-House

    It is generally agreed that house museums (properties that are preserved as homes to be visited by the public) are not financially prudent uses to retain historic properties. Recent studies conclude that a compromise must occur between balancing original historic character with up to date and flexible programming space to achieve viable long-term solutions for unique homestead-era properties.

    Written By Marion Rosas and Peter Meijer, AIA, NCARB / Principal

    Abstract: Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

    When we think of energy conservation standards for our built environment an increasing amount of existing buildings do not comply with today’s standards. A large portion of these existing buildings are from the mid-century modern era. Additionally, mid-century modern buildings are approaching historic status, if not already there. This status compounds finding the best way to integrate current energy standards because aesthetic impacts to a historic resource must be kept to a minimum. At PMA we believe that while challenging, it is possible to maintain the integrity of historic mid-century modern buildings while meeting new energy conservation requirements. In an effort to explore this possibility, we have submitted an abstract for an upcoming Energy Conservation in Mid-Century Modern Buildings Symposium presented jointly by APT Northwest and DOCOMOMO_Oregon.
    window-detail
    Abstract: Best Practices for Providing Effective Daylight in Mid-Century Modern Structures
    Effective daylighting can reduce both lighting and cooling loads while improving user comfort, satisfaction, and health. Despite plentiful glass, using daylight in mid-century modern building can be challenging. Glare and uneven light distribution can cause user discomfort and pose challenges to effectively daylighting spaces. Frequently, artificial lighting is used to balance lighting in spaces over lit by the sun, negating any potential energy savings. For existing buildings, the available methods to provide effective daylighting are limited by the existing constructions and configuration. To both preserve existing structures and provide ample daylight a critical question must be answered – what are the best practices for improving daylight in existing buildings? This study provides insight to daylighting existing structures, specifically, how light can be controlled and distributed in mid-century modern buildings with plentiful glazing.

    Emerging tools and technologies provide effective methods of analyzing hundreds of different daylighting simulations. Applications such as Grasshopper and Dynamo allow users to explore a variety of different design interventions and determine optimal solutions. This study explores and analyzes how common daylighting strategies can be implemented on existing mid-century modern structures. The study focuses on a 1963 residential tower in Portland, Oregon, and explores how interior reflectivity, interior/exterior light shelves, shading, and glazing can impact daylight availability and distribution. The study looks at a variety of ways each strategy can be implemented and analyzes the results to determine best practices based on daylight distribution/availability, glare, lighting loads, and heating/cooling loads.

    Speaker Bio
    Halla Hoffer, AIA
    Associate / Peter Meijer Architect, PC

    Halla is passionate about rehabilitating historic and existing architecture by integrating the latest energy technologies to maintain the structures inherent sustainability. Halla joined PMA in 2012 and was promoted to Associate in 2016. She is a specialist in energy and environmental management, as well as building science performance for civic, educational, and residential resources. Halla meets the Secretary of the Interior’s Historic Preservation Professional Qualification Standards (36 CFR Part 61).

    Integrating Universal Access with Historic Architecture

    Oregon State University (OSU) is dedicated to providing universal accessibility throughout its Corvallis campus. The historic Memorial Union building opened in 1927, and is an important gathering place on campus. In its current configuration, the rotunda entry access poses challenges to complying with current ADA Standards for Accessible Design. PMA with our multidisciplinary team members are addressing how to improve the arrival experience starting from the Quad by focusing on the front door as the primary accessible entry, while retaining the buildings historic integrity. With an integrated approach there will be a primary travel path for all.

    The existing limitations of accessibility to the MU are the existing ramps do not lead to the front entrance and the circulation through the rotunda requires use of non-compliant ramps. The existing exterior 1980s ramps were built interior of the terrace’s balustrade wall and access is not intuitive and requires signage. They take up significant portion of the historic terrace with circulation and railings.
    pmapdx-osu-mu-accessible-design
    OPPORTUNITY FOR INTEGRATING UNIVERSAL ACCESS
    The renovation of OSU MU Rotunda provides an opportunity to highlight the integration of universal access to historic properties. The vision for a new accessible path is integrated into the highly ordered Neo-classical design of the MU creating a symmetrical entry on either side of the grand entry stairs facing the quad. The design seeks to reactivate the formal side terraces by eliminating the clutter of handrails and circulation space that currently breaks up the space.

    The new accessible pathway will be a sloped walkway along the exterior of the existing balustrade wall of the terraces. A 4.5 % sloped walkway will be integrated into the landscape and will free the space of guardrails. This will result in greater visibility of the accessible means of access to the building and restore the original spatial function of the terraces. Another slope walkway will lead from the terrace to the front entrance and will be integrated into a tiered landscape and informal setting area. The new design will reactive the terraces by streamlining circulation and providing new seating opportunities.

    PROPOSED DESIGN OPTIONS
    Two design options were explored for this scheme. The first design option removes a portion of the balustrade wall closest to the grand entry. This would open up views of the entry and terrace to the quad and provide additional visibility of the accessible pathway. The second option would leave the balustrade wall in place and would create more of an intimate feel along the terrace. Below are renderings of the first design option.
    pmapdx-osu-mu-accessible-design
    pmapdx-osu-mu-accessible-design
    pmapdx-osu-mu-accessible-design
    pmapdx-osu-mu-accessible-design

    We will update this entry as the project develops. Stay tuned!

    Written by Hali Knight.

    Preservation Month 2017

    May is Preservation Month! Review ten (10) handy preservation resources:

    ONE – We explore some factors and opinions on new construction in Historic Districts.
    PMAPDX OSU Buildable Landarea

    TWO – An iconic example of a landmarked building less than 50 years old.
    portland-building-pmapdx-nomination

    THREE – Visit Oregon’s SHPO website to browse historic sites, NR listings, & available grants.
    Union Station Historic/Seismic Renovation

    FOUR – Get to know your local architectural styles from the 1840s – 1970s.
    Hillsboro J-B House

    FIVE – Pledge your support for a rehabilitated VMC because this place matters.


    SIX – How you can find a historic place in the state of Washington.
    PMAPDX-planning

    SEVEN – Tax Incentives for Preserving Historic Properties.
    USCH Courtyard

    EIGHT – Oregon’s Most Endangered Places via Restore Oregon.
    PMAPDX modern survey historic photo

    NINE – Keeping It Modern. An architectural conservation grants for 20th century buildings.


    TEN – How Historic Preservation is Reviving America’s Communities.
    Hillsboro_OrencoInventory

    Long Term Impacts of Masonry Waterproofing Sealers

    Product X works as a masonry sealer, but what are the long-term ramifications of using Product X on masonry buildings? Masonry sealers come in a wide variety of formulations, but how do the various chemical compositions react to environmental conditions and what affect does the formulation have on the masonry? Most masonry waterproofing sealers specified by architects and conservators, installed by contractors, and requested by property owners are based on Silicone (═Si═ ) chemistry. There are three popular groups of silicone based materials being used as waterproofing materials: 1) silicates, 2) the group of silane, siloxane, siliconate; and 3) silicones. Silicates, similar to Product X, provide waterproofing properties by filling the pore structure of building materials with silicon dioxide (SiO2) precipitation. Common silicates are sand, Portland cement, and other natural occurring minerals. Silanes, siloxanes and siliconates provide waterproofing properties by bonding with the substrate. They are often referred to as penetrating sealers. Silicones do not form chemical bonds with the substrate. Silicones provide waterproofing properties by forming a non-bonded film. Such products are labeled as thin-film sealers.
    WSU-PMAPDX_masonry_sealers
    Silicates
    Silicates are most commonly used in crystalline type water proofing agents for concrete. Their use is generally focused on concrete substrates. However, it is known that strongly alkaline, aqueous solutions of methyl silicates can be used to impregnate masonry. Such solutions often depend upon caustic soda for their alkalinity. Impregnation of masonry with such solutions is often disadvantageous, however, particularly due to the high alkalinity. For example, the high caustic soda content of the solution will cause a gradual removal of the organosilicon compounds from the interstices of the masonry by chemical combination with the surfaces of the masonry surrounding the interstitial voids. Moreover, the caustic soda solution reacts with carbon dioxide or other acidic components of the air which gives rise to salting out and the formation of efflorescence on the masonry. (1)

    Silane, Siloxane, Silconates
    Silane, siloxane, silconates are penetrating type of sealants. Their effectiveness is dependend on the porosity of the substrate and the dosage of repellant applied. Each manufacturer will have unique requirements for the application and dwell time of their sealer. Silanes and siloxanes form a chemical bond with siliceous containing materials. Silanes and siloxanes go through three reactions when applied to a masonry surface: hydroloysis, condensation, and bonding. During the condensation phase, the moisture vapor transmission rate is critical to preventing moisture accumulation behind the sealer layer.

    With penetration type sealers, it is critical to the longevity of substrate (masonry) that the moisture vapor transmission of the sealer is actually known. There has been very little third party testing of vapor transmission and each product manufacturer provides varying ways of testing transmission. In addition, the active ingredient content of the sealer formulation and the coverage rate will greatly affect the moisture vapor transmission. In other words, performance in the field will vary greatly from highly controlled laboratory testing.

    Siliconates are water soluble and they impart water repellency on porous surfaces. A drawback to using diluted siliconate solution for waterproofing applications is that siliconates react with carbon dioxide and carbonatious matters present in the substrate to form a water repellent, water-insoluble, white colored precipitate. This white layer may become quite visible and require aggressive removal procedures resulting in objectionable appearance or scarification of the surface during removal processes.

    Silicone
    The effectiveness of silicone sealer depends on the alkyl group used (which directly influences its resistance to alkaline conditions), the amount of exposure to ultraviolet light and the level of moisture in the masonry when the silicone is applied. (2)

    The proliferation of masonry coatings on the market, and the continued pervasive use of the coatings, requires the architect, engineer, contractor, and conservator become more knowledgeable on the wide variety of coating formulations, the continued evolution of those formulations, and understand both the right application of the product and potential detrimental effects of using the wrong product on historic substrates.

    WSU-PMAPDX_masonry_sealers_002
    CASE STUDY: WASHINGTON STATE UNIVERSITY, DUNCAN DUNN HALL
    In preparation of a major renovation, Peter Meijer Architect, PC was retained in 2010 to conduct a general exterior condition assessment of Duncan Dunn Hall on the campus of Washington State University, Pullman, Washington.

    Duncan Dunn was constructed in 1926 as a women’s dormitory for Washington State University, then named Washington State College. It is located in the heart of the WSU campus, facing north towards Linden Avenue. First known as the “New Dorm,” the building cost $150,000.00 to build at that time, and could house 140 students. The architect, Stanley Smith, was the head of the department of architectural engineering and was also the official University Architect.
    WSU-PMAPDX_masonry_sealers-004
    The predominant material present on Duncan Dunn is a solid brick unit, brownish red in color, and approximately 8” x 3 7/8” x 2 3/8” in size. At the time of assessment the brick had a very prominent unsightly, white coating over 60% of the masonry facades.

    WSU-PMAPDX_masonry_sealers-003Believing the white haze was a result of UV degradation of a masonry sealer, PMA conducted Reunion Internationale des Laboratoires D’essais et de Recherches sur les Materiaux et les Constructions (RILEM) tube tests of water absorption on the exterior brick on Duncan Dunn Hall. The area of brick chosen for the test was out of direct sunlight to avoid affecting the results and was conducted during dry weather. No movement of the water over a 45 minute period was recorded during the test. Masonry units, even those constructed with high quality clays under controlled firing conditions will absorb some water. The results of the field test on Duncan Dunn, along with the white surface haze, reinforced the assumption of the presence of a masonry coating.

    Communication with WSU personnel and their internal research surmised that “the building may have had a sealer put on after the original construction. [WSU cannot verify the application through original records] but do know [that a sealer] was not used on a regular basis after [construction completion.] Back in the 70’s some “miracle sealer” of some sort was introduced on Campus and used at a few locations. Duncan Dunn Hall was among the buildings [receiving masonry sealers.] Today you can see the remnants of this as a white powdery surface that almost looks like efflorescence. [WSU] does not know the name of [the sealer] product.”

    To confirm the presence of the sealer, PMA conducted lab testing via polarized light microscopy (PLM) episcopic microscopy, capillary fusion and Fourier-transform infrared spectroscopy (FTIR) per ASTM D1245 and E1252, respectively. FTIR indicated the material to be Poly(2-hydroxypropyl methacrylate), an initially water-miscible acrylic polymer that in these samples is at present very brittle and sloughs rather easily.Testing confirmed the presence of a “water-miscible acrylic polymer”. Due to chemical breakdown under UV, the chalky coating remaining on Duncan Dunn is no longer soluble in water.Because of the insoluble nature of the white haze, low pressure hot-water cleaning methods would not be successful. PMA recommended the Rotec Vortex cleaning system using a mirco-abrasive mixture of dolomite, water, and air. Ultimately this removal processes was successful with no damage to the masonry surface.

    (1) Patent application for new formulation of sealers. (2) Types of Masonry Water Repellents, GSA web site. Information derived from ProSoCo Inc. product literature.

    Written by Peter Meijer AIA, NCARB / Principal

    Analyzing Historic Masonry Wall Performance

    Wilmer-Davis Hall is a residential complex on the Washington State University (WSU) Pullman campus. Built in 1937 by Architect Stanly Smith, with John Maloney, the six-story structure is composed of masonry and concrete with a masonry/brick veneer in the classical and Georgian Revival architectural styles. For a recent feasibility study of the complex, PMA provided an exterior assessment and a limited moisture study utilizing Wärme Und Feuchte Instationär (WUFI), an industry standard application in predicting wall performance to determine how additional insulation may impact the existing constructions and wall performance.

    The primary concerns of this analysis included increased potential for freeze thaw action and increased mold growth as a result of added insulation. When historic buildings are insulated the insulation is typically added to the interior of the structure to prevent alterations to the exterior appearance. This often causes the outer layers of the wall to be both colder and wetter as the materials are no longer warmed and dried by the interior heating system. The additional water and more extreme temperatures can result in an increase in freeze thaw action, corrosion of metal reinforcement, and/or increased mold growth.

    Additionally adding insulation to a wall changes the location of the dew point within that construction (the point at which vapor in the air condenses into water). A dew point within the middle of the wall can also result in increased moisture within the wall cavity. If a wall has difficulties drying due to any of the above causes it is possible that over the course of several years the quantity of water within the wall will consistently increase. Accumulation of water will exacerbate reinforcement corrosion and mold growth and can result in increased freeze thaw action. This study focused on the following metrics to analyze proposed wall performance: quantity of water in the assembly, quantity of water in each material layer, relative humidity in layers susceptible to mold growth, and isopleths.

    MODEL SETUP
    As in any simulation analysis a number of assumptions were made regarding the existing wall construction and the proposed design conditions. A variety of different conditions were analyzed in order to explore the range of conditions and variables. Below is a description of the inputs as well as an analysis of the results.

    Four (4) proposed wall constructions were analyzed to determine how different types, quantities, and configurations of insulation would impact the existing constructions. The configurations were based on outlined solutions for meeting Washington State Energy Code (WSEC) or providing improved thermal comfort. Two of the proposed constructions meet WSEC (Option 1 and Option 2), while two of the solutions (Option A and Option B) fall short of fully meeting WSEC, but would provide improved insulation values. The options simulated included:

    Base Case (Existing Conditions) (R-4.8)
    3-1/2” Masonry
    1” Air Gap
    7-1/2” Hollow Clay Tile Back-Up Wall
    1-1/2” Plaster

    Option 1 (Meets WSEC) (R-15.4, continuous insulation)
    3-1/2” Masonry
    1” Air Gap
    7-1/2” Hollow Clay Tile Back-Up Wall
    1-1/2” Plaster
    2” Expanded Polystyrene
    Vapor Retarder (1perm)
    0” Gypsum

    Option 2 (Meets WSEC) (R-20.9, insulation is not continuous)
    3-1/2” Masonry
    1” Air Gap
    7-1/2” Hollow Clay Tile Back-Up Wall
    1-1/2” Plaster
    3” Batt Insulation
    0-1/2” Expanded Polystyrene
    Vapor Retarder (1perm)
    0-5/8” Gypsum

    Option A (R 17.4, insulation is not continuous)
    3-1/2” Masonry
    1” Air Gap
    7-1/2” Hollow Clay Tile Back-Up Wall
    1-1/2 Plaster
    2” Foamed-In-Place Polyurethane
    Vapor Retarder (1perm)
    0-5/8” Gypsum

    Option B (R-18.4, insulation is not continuous)
    3-1/2” Masonry
    1” Air Gap
    7-1/2” Hollow Clay Tile Back-Up Wall
    1-1/2” Plaster
    3-1/2” Batt Insulation
    Vapor Retarder (1perm)
    0-5/8” Gypsum

    Materials It should be noted that no material testing was performed during this phase of the project – instead default material properties were chosen from the WUFI database. Materials used include:

  • Masonry: The material ‘Brick (Old)’ was used to simulate the existing masonry. The material is a generic historic brick material compiled from a variety of different bricks and included in the WUFI database.
  • Airspaces: All airspaces were modeled without additional moisture capacity which according to WUFI, models more realistic moisture storage in air cavities.
  • Hollow Clay Tile: The historic drawings indicate that behind the masonry is hollow clay tile. WUFI does not have a default material for hollow clay tile. Instead a masonry material ‘Red Matt Clay Brick’ was used to represent the solid portions of the clay tile. Air spaces were used to simulate the hollow portions of the tile.
  • Historic Plaster: The WUFI database does not have a default historic plaster material. The ‘Regular Lime Stucco’ material was used to simulate the existing plaster.
  • Batt Insulation: ‘Low Density Glass Fiber Batt Insulation’ was used in simulations.
  • Rigid Insulation/Expanded Polystrene: ‘Expanded Polystyrene’ was used in simulations.
  • Fomed-In-Place: ‘Sprayed Polyurethane Closed-Cell’ was used in simulations
  • Gypsum: ‘Interior Gypsum Board’ was used in simulations.


  • Weather/Interior Conditions In each simulation the model was set to mimic extreme situations to verify that the existing walls will perform in all conditions. The Spokane, Washington weather file indicates that the south elevation should have the most wind driven rain and moisture impacting the wall. Given this information the analysis used south exposure and the Spokane weather file to simulate exterior conditions. For the interior climate conditions the following profiles were used:

  • Interior temperatures ranging from 69 °F to 72 °F
  • Relative humidity ranging from 50% – 60%


  • The above values represent a relatively high moisture load which is consistent with the existing use as a residential facility.

    Water Intrusion Additionally as per ASHRAE 160 a small leak (1% of driving rain) was introduced into the exterior assembly to simulation a scenario where water was penetrating the exterior surface. This could occur at bondline failures in the mortar or penetrations through the wall assembly. The leak was placed past the masonry veneer on the face of the hollow clay tile backup wall.

    Initial Conditions Lastly the initial conditions of the materials were determined using ASHRAE 160. For existing wall materials EMC80 was used as the initial moisture content. (EMC80 is a value expressing an equilibrium of water and material masses at 80% humidity). For new components the expectation was that the materials would be installed from the interior and would remain dry during the construction process – thus EMC80 was used for new components as well.

    WUFI RESULTS
    Four metrics were used to interpret and analyze the following WUFI results: Total Water Content/Water Content in Material Layers, Temperature, Relative Humidity, and Isopleths.

    Total-Water-Contents-WSU-Wilmer-Davis-WUFI-Report-6Total Water Content WUFI can predict the total accumulation of water over the time frame of the simulation, in this case five years. Over the course of each year a wall assembly will be wetted by the rain, and dry over the summer months. Differences in humidity and temperature between spaces may cause water condensation within the walls. If conditions do not allow condensation or other water to dry, materials may accumulate water over a period of time.

    The chart above shows how each of the different simulations performed. Note that total water content is measured per ft2 of wall. Walls that are thinner (existing construction) will inherently have less capacity to hold water. In general all of the walls performed in a similar manner – an indication that the retrofit strategies should perform in a comparable manner when compared to the existing walls. As can be seen in the chart, all of the simulations, including the base case showed some accumulation of water over the five year simulation. These results, however, do not conclusively show that the proposed walls will accumulate water. The results indicate that even the base case is accumulating water over time. During PMA’s site visit, however, the existing exterior walls appeared to be performing well – which would not be the case if they were consistently accumulating water. Additional analysis showed that the gradual accumulation of Total Water Content appears to be a result of initial instability within the wall construction that equalizes over time. A 20 year simulation showed accumulation over the first five years, after which the water content stabilizes.

    Water Content in Material Layers Each of the individual layers of material in a wall assembly have the capacity to hold and retain water. A high water content in any individual layer can indicate the potential for mold growth, the possibility for damage associated with freeze thaw, and a reduction in R-Value based on moisture content. Mold growth is possible when the moisture content is above 20% and if the material has the capacity to feed mold growth. The charts below show how each simulation performed for each layer within the wall.

    Water-Content-Materials-WSU-Wilmer-Davis-WUFI-ReportIn general most layers remained well below the 20% threshold for mold growth. The insulation layers, however, are an exception. Options 2 and B both had batt and/or foam insulation which yearly exceeded 20% water. This quantity of water is somewhat concerning for the batt insulation as it may reduce the material’s R-Value and/or contribute to mold growth depending on the composition of the material. Solutions that used foam insulation performed better than those with batt insulation.

    Temperature One common result of insulating a historic building from the interior is increased freeze thaw action. Insulation prevents the interior conditioned space from heating and drying the exterior masonry. As a result the masonry is typically saturated with more water and exposed to colder temperatures. The analysis looked at the temperature within the middle of the masonry to determine how added insulation would impact the material. A chart comparing the base case to the four options for insulation is located below. As can be seen the brick temperature remains consistent with the base case in all retrofit options. This is an indication that the masonry may not by exposed to additional weathering as a result of added interior insulation. It should be noted that not all masonry reacts to water saturation and freezing conditions in the same manner. To further analyze the masonry’s susceptibility to freeze-thaw action lab analysis is recommended to determine material performance. If results indicate that the masonry is susceptible to freeze-thaw it will be critical to ensure new constructions do not lead to a significantly colder/wetter exterior wall.

    Relative Humidity The relative humidity of the air within the wall construction also has an impact on material longevity and mold potential. A high relative humidity in plaster or batt insulation layers may indicate mold growth, while a high relative humidity in layers with reinforcement may indicate the potential for corrosion. A constant and high relative humidity (above 80%) indicates the potential for mold growth. The charts to the right focus on several susceptible layers, the existing plaster, batt insulation, and gypsum board. In general the majority of the layers susceptible to mold remained below 80% relative humidity, or consistently dropped below 80% relative humidity allowing the material to periodically dry. An exception was the existing plaster layer. The addition of interior insulation caused the relative humidity within the layer to increase approximately 15%, from 65% (base case) to just over 80% (all options for added insulation). This spike in relative humidity is concerning and could indicate the potential for mold growth within the layer.
    Materials-Temperature-Relative-Humidity-WSU-Wilmer-Davis-WUFI-Report
    Isopleths WUFI can also predict mold growth by plotting isopleths on the interior surface. The isopleths are plots of the temperature and the relative humidity for every time period calculation. When the temperature and relative humidity both exceed the limiting lines calculated by WUFI there is the potential for mold growth. The simulations indicate that there is very little potential for mold growth. All of the simulations begin above the limiting lines, but over time equalize and remain well below the threshold calculated by WUFI.
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    CONCLUSIONS
    The results described above indicate that there could be some challenges to designing an appropriate insulation system for Wilmer Davis Hall. Three of the primary concerns noted in the above analysis are: increasing total water content quantities; high quantities of water in the batt insulation layers; and consistently high relative humidity’s in the existing plaster layer.

    In general Option 1 and Option A performed better than Option 2 and Option B – primarily because they relied on only foam/rigid insulation. This resulted in no risk of mold growth within the insulation layers and no reduction of the R-Value. Concerns were still identified with both Options in terms of total water content and relative humidity in the plaster layer.

    Prior to detailing a new wall for construction additional analysis is recommended. Minor changes in material properties can have significant impacts on wall performance. The above analysis has indicated that there is a potential for mold growth, but has not confirmed its likelihood. Most of the metrics indicated no risk of mold growth – however because some of the metrics showed a potential for mold, additional analysis is recommended. Testing of the existing materials and specific data on proposed products should be used to refine this analysis and determine extent of mold growth risk.



    Written by Halla Hoffer, Associate, Architect I

    Overview of Architectural Styles in Oregon: 1840s to 1970s

    The City of Gresham applied for and was granted a CLG grant from the State Historic Preservation Office to increase community interest in historic preservation. The City felt that a presentation focused on architectural styles would be likely to generate some interest. They contacted PMA to find out if we would work within their budget and provide a powerpoint presentation geared towards citizens with no planning or architecture background, but also useful for City staff and historians. PMA was happy to be able to provide an overview of Oregon architecture styles from “settlement era” up until mid-1970s. The presentation highlighted the styles most likely to be seen in the Gresham area, especially residential and commercial uses. It was educational for our office to find those historic properties in Gresham and incorporate some of them into the presentation.

    Use, Type, Style
    It is difficult to understand style without an appreciation of the ways style can be overlaid on various types and uses of buildings. The USE of a building is its primary function. For instance, a church (use) might have a hall with steeple (types or forms) and be Neoclassical (style). The use or purpose of a building is strongly linked to its form, but even within a category of use such as residential, one might find various types such as “apartment block,” “bungalow,” or “four-square.” TYPE just means the basic form, so it is useful for historians to categorize these forms into expected sizes or arrangements of volumes. An apartment block is generally a simple rectangular building with several apartment units and a shared entry. A bungalow is simply a small house, one or 1.5 stories, horizontal in expression. Bungalows are often Craftsman in style, but a handful of other styles are sometimes used with a bungalow type. A four-square is a larger house, typically 2 or 2.5 stories, consisting of a somewhat square footprint with 4 rooms on each floor, and a broad front porch with columns or posts.

    The building’s STYLE is determined by the architectural and ornamental details and exterior features applied to the basic structure. Styles change with the times. In fashion and out of fashion, some endure longer. The timeline included is generally reflective of Oregon architectural fashions. However, style also can be affected by technology- for example, the development of steel frame buildings allowed for a new style to emerge: Modernism. Older bearing-wall masonry construction only allowed for small windows set between structural wall areas. A proliferation of new building types, such as the geodesic dome, occurred in the Modern era.

    We categorize buildings by type, use, and style when doing a survey of resources in a particular area. The data can be compared quickly and easily to data from other surveys, so we can see the patterns and history of development emerging in any particular area.

    Stylistic Timeline of Architectural Styles in Oregon
    From Vernacular Forms and Styles, to Renaissance Revivals, Northwest Regional Style and Post Modern, Oregon has a robust and diverse vocabulary of architecture. The stylistic timeline below is meant as a broad overview, highlighting key attributes per style listed, to help you identify your local and regional architectural resources.

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    Written by Kristen Minor, Associate, Preservation Planner

    The Form and Function of Lighting Design

    When we experience an interior architectural space, lighting plays a large role in setting the mood and functionality of a space. No matter an existing, modern or historic building, light of a space is a critical aspect of great interior design. Lighting elements can be designed to enhance the space and architectural details, set the mood, and compliment furniture, color schemes, and art work. For spaces without an abundance of natural light, lighting design becomes even more critical design consideration. For a recent project, PMA designed lighting schemes for two historic four-story tall interior atriums.

    The existing atriums utilize natural light from skylights above; however the original design provided no artificial overhead lighting in the space. During the winter months or at dusk and night, the light quality of space relies on the little ambient light from the skylights or artificial light from the surrounding rooms and halls. The light during these times is inadequate for the necessary function of the space. PMA was tasked with providing a lighting solution that would sensitively address the historic nature of the atriums and provide adequate visibility in the space.
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    Defining the Project Challenges
    The concepts for our lighting schemes were based on the intended function of each identical space. The focus of the design and specified need of the client was to provide lighting for evening social gatherings, networking, and overall entertaining. Lighting needed to be adequate enough for speakers presenting to a crowd and for listeners to be able to read any related literature. Therefore, it was crucial to design lighting schemes that could provide ample lighting for evening events without compromising the historic integrity and ambiance of each space. To provide a solution for our clients’ challenge, we considered the following when approaching our design for the lighting schemes:

  • How to provide power to the source of lighting without compromising the historic elements.
  • Designing for large volumes of vertical space: hanging lighting within the atrium versus lighting from the top; how the light travels in the space, how it casts down shadows, the reflections off the floor and other surfaces.
  • One atrium exhibits permanent hanging sculptures and art; the lighting design required minimal approach to integrated and highlight the sculpture without distracting from it.
  • Designing for and highlighting the atriums’ architectural details, like the cornices, in addition how to hide or incorporating other non-historic architectural details like the structural support columns.
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    Methodology for Design Solutions
    The prominent design goal was to increase overall light levels through a refined, modern scheme that would provide juxtaposition to the historic architectural elements and hanging sculpture. As in any historic project, it is important to avoid solutions that are faux historic, competing with, compromising, or confusing the original historic character. The few pragmatic design parameters defined by the client allowed for design freedom to provide several unique, distinct solutions. While creating our designs, PMA experimented with the type of fixtures (down lights, sconce, defused) and placement of these fixtures within the large volume of the atriums. PMA explored these options in a Revit model of the atrium spaces, which enabled evaluation of the design solutions through lifelike renderings that portrayed the quality and levels of light. Illuminance studies of lux levels provided a way to evaluate each design and provide refinement to meet necessary levels defined by the function of the space. Some lighting design options included:

  • Design lighting to highlight and contrast architectural features from surroundings, for example placing fixtures in the cove of architecture cornices located above openings within the atrium.
  • One atrium has a glass block floor element which could be illuminated from below to provide a dramatic light feature.
  • Accenting the verticality of the space with defused ribbon lighting set within the non-historic structural C-channels. This would transform these elements into elegant vertical lines leading the eye to the above skylights.
  • Pendant lights interspersed between sculptures would provide orbs of light to highlight elements of the sculpture. These fixtures would provide defused-light with optional downlights within the same fixture.
  • Suspended down lights at top of atrium with lights accenting sculptures from above and side.
  • Wall sconces to accents light and wash the atrium walls and columns; this would provide an overall glow to the space.
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    Scheme 1 unified serval lighting design ideas to provide different light level options in the space. Wall sconce lights provide general illumination of the space. Large circular hanging fixtures consist of defused tube lights and large circular defused downlights. Each group of fixture types can be controlled independently and dimmed to provide the ambience desired.

    Scheme 2 specifically works with the sculptures in the second atrium space. Vertical ribbon lights provide ambience illuminance of the space while concealing non-historic structural elements. Pendant lights hang interspersed within the sculptural elements. These have a defused light with an option for downlights. Each grouping of fixtures can be illuminated together or separately depending on the quality of light needed.

    Scheme 3 was chosen by the client and until announced must remain confidential. Stay tuned for the reveal.


    Written by Hali Knight.