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Back to School: A Historic Overview of Benson Polytechnic HS

For a recent Portland Public School (PPS) project, PMA had the pleasure of creating a Historic Overview of Benson Polytechnic High School for a broader master planning project for the campus. The goal of the historic overview was to conduct an assessment of the school’s campus, highlight new building additions and alterations (changes overtime), and to identify and define historically significant spaces. As part of the historic overview, PMA reviewed historic drawings and photographs, PPS archival material(s) and coordinated discussions with school staff. Resources assessed included: Main Building (1916), North Shop Wing (1917), South Shop Wing (1918), Old Gym (1925), Auditorium (1930), Library Science Addition (1953), Aeronautics/Automotive Shop (1953), New Gym (1964), New Library Addition (1991), and KPBS (1992). Below is a snap-shot of our findings included in the Historic Overview of Benson Polytechnic High School.


photo courtesy of PPS archives.

Background and History
Benson Polytechnic High School was built in 1916 and designed by former architect and superintendent of school properties for Portland Public School, Floyd Archibald Naramore (i). Supported and funded by Simon Benson, a local lumber baron and philanthropist, the school was built to reflect modern educational ideals and the industrial arts. According to the 1915 school district board of directors meeting minutes, Simon Benson offered to donate $100,000 to the school district for “the purpose of building the first unit of a School of Trades, upon condition that the district contract to expend at least $100,000 during the year 1916, in the construction of a second unit to the school.” (ii) This donation was accepted by the school district, and in 1916 construction began.

Historic Overview
Overall, Benson Polytechnic High School has shown significant changes over time. These changes have occurred to the campus as it has grown from just the main building in 1916 to the existing 10-unit campus it is today, and to most of the school buildings.

Originally, the site just consisted of the main, rectangular-shaped building to the west of campus. Designed with the intent to grow over time on a six-block parcel, this building and its campus did. By 1924, the site included the north shop wing with saw-tooth roof and foundry building to the northeast, the south shop wing with saw-tooth roof to the south, and the boiler building in between them all. The site was connected by a covered walkway that ran from the east façade of the main building, along the north and east façades of the boiler building to the north wing shop along its south façade and the south wing shop along its north elevation. At this time, the site also included a one-story portable building to the southeast of the main building.

By 1950, the site had grown again. At this point, the site included the old gym to the south of the main building, the auditorium to the north of the main building, and ten new portable classrooms, including an aviation classroom and shop where it is currently located, war production training building where KPBS is currently located, and a music room where the new library addition is currently located. During this time, the site still included the covered walkway that connected the building and remained relatively open.
Significant Changes
Currently, with the addition of the aeronautics/automotive shop and library science addition in 1953, the new gym in 1964, the new library addition in 1991, and KPBS in 1992, the Benson Polytechnic High School site is significantly different from its early beginnings. With the addition of these later period buildings, the site has become denser with the main building connecting to 50% of the campus buildings. The covered walk way has since been demolished leaving most of the site circulation to the interior. However, much of the site still reflects the school’s period style and building methods along the site’s two primary thoroughfares, NE 12 Avenue and NE Irving Street. Like the site, many of the early constructed buildings have changed as well.

Of the five buildings built before 1930, the north wing and south wing shops have endured the most significant alterations. These alterations include the removal of their saw-tooth roofs, the additions of centralized locker-lined corridors, the reconfiguration of room sizes, the infill of original openings, and the replacement of original wood windows. The north wing shop experienced most of these alterations in 1958 and the south wing shop experienced all of these alterations in 1960. The two-story unit in the north shop wing underwent significant changes in 1977. These changes include the reconfiguring of most rooms, and the addition of new exterior CMU stairs and primary entrance, the removal of original staircases, wood columns, and chimney. The foundry room was also altered in 1977, as its second-level balcony and spiral staircase were removed and enclosed.
Well Preserved Character Defining Features
Overall, the character-defining features throughout each building are well preserved. This retention of several original interior spaces, features, and finishes contribute to Benson Polytechnic’s High School good historic integrity. As this school and campus continue to change, its significant structures and their character-defining features will add to the rich vitality of the school and contribute to the importance of the school as a community asset.

(i) Entrix, “Oregon Historic Site Form: Benson High School,” Oregon Historic Sites Database, compiled 2009, http://heritagedata.prd.state.or.us/historic/index.cfm?do=v.dsp_siteSummary&resultDispl ay=50450.

(ii) Meeting of the Board of Directors, School District No. 1, July 31, 1915.

Written by Kate Kearney, Associate, in conjunction with PMA Planning staff.

When Field Performance of Masonry Does Not Correlate with Lab Results

First presented at RCI 2015 Symposium on Building Envelope Technology, Nashville, TN


When it was completed, Grant High School was typical of the high schools constructed by Portland Public Schools in the pre-World War II era. In addition to being an extensible school, including educational buildings constructed between 1923 and 1970, the school was also reflective of fire-proof construction through its use of a reinforced concrete structure with brick in-fill. (Portland Public Schools, Historic Building Assessment, Entrix, October 2009)

Over the last fifteen years, Portland Public Schools (PPS) noted an accelerated degree of masonry face spalling on the original 1923 main building and 1923 Old Gym particularly when adjacent to concentrated sources of surface water. Other areas of spalling were not as obvious including protected wall surfaces. The masonry spalling was not occurring on later additions including the north wing (circa 1925), south wing (circa 1927), and auditorium building (circa 1927). Upon closer visual examination, it was observed that individual units were failing in isolated protected areas of the wall surface. Failures in such areas could not be accounted for under direct correlation of heavy water intrusion and typical failure mechanisms.

The failure of the brick was potentially due to a number of separate or cumulative conditions including 1) excessive water uptake by the brick; 2) sub-fluorescence expansion of salts in the masonry, 3) freeze thaw; 4) low quality of the original 1923 brick; and 5) the application of surface sealers preventing water migrating to the exterior surface.


Field Investigation
In order to determine if the damage to the masonry was deeper than the surface, several wall-lets, an invasive exterior wall opening, were performed confirming the assembly of a multi-wythe masonry wall constructed in a typical fully bedded bond course with interlocking headers and no cavities between the first three brick courses. Hooked shaped, 3/32” gage, steel wire masonry ties in alternating courses and approximately twelve inches (12”) on center ties were found to be in good condition with no deterioration. The absence of corrosion on the in place brick wire ties indicated that little moisture was present inside the multi-wythe wall.

As a result of the hypothesis and field observations, it was prudent to conduct a series of lab tests to the brick, mortar, and patch materials to assist in the determination of 1) the quality of the brick; 2) the physical composition of the brick; 3) the quantity of naturally occurring compounds in the masonry and mortar, particularly salts in the masonry; and 4) the quality of the mortar. The findings would help narrow the potential cause of the spalling and lead to a more focused repair and maintenance process. Bricks were removed for testing of Initial Rate of Absorption (IRA – a test for susceptibility to water saturation) freeze thaw testing, and petrographic analysis, a way to determine the inherent properties of the clay and manufacturing process. Both pointing and bedding mortar samples, as well as, the previous patching material were removed and also tested. To rule out damage caused by maintenance procedures, faces of the brick material were sent to determine if sealants were used on the brick and, if present, determine the sealant chemical makeup. The presence of a surface coating may lead to retention of water within the brick and thus prevent natural capillary flow, natural drying, and water evaporation.


Testing & Results
Samples sent to the lab for coating assessment were analyzed via episcopic light microscopy, and Fourier- Transform Infrared Spectroscopy (FTIR) per ASTM D1245 and ASTM E1252. The results found no hydrocarbon or organic formulations used on the surface of the brick refuting the hypothesis of a surface sealer.

Following modified ASTM standards, a 24-hr immersion and 5-hr boil absorption test on the brick were performed. The brick have a very low percent of total absorption at 9.5% for the 5-hr boil and 7.5% for the 24-hr test. The maximum saturation coefficient is 0.79 which is 0.01 over the maximum requirements for Severe Weathering bricks recommended for Portland climate (ASTM C216-07a Table 1). The Initial Rate of Absorption (IRA) is 5.7g/min/30in2 which equates to a very low suction brick or brick with low initial rates of absorption. The freeze thaw durability tests resulted in passing performance. All of these tests refuted the hypothesis that freezing temperatures were the cause of masonry spalling.

A brick material analysis was performed in general conformance with ASTM C856, ASTM C1324 (masonry mortar) and included petrographic analysis, chemical analyses, x-ray diffraction and thermogravimetric analysis. Samples were analyzed under a polarized light microscope for information such as materials ratio and presence or absence of different deterioration mechanisms. These tests were used to assess the overall quality of material, presence of inherent salts, excessive retempering, cracking, ettringite formation, and potential alkali‐silica reactivity.


The Petrographic Characterization resulted in the most unusual findings and the most relevant results related to the observed failures. The polarized light microscope indicated carbonate based salt crystals seeping into the masonry from the mortar. No sulfate based salts, typically associated with the clays used for making brick, were present. Furthermore the inherent properties of the brick showed very small rounded voids and interconnected planer voids. Planner voids result from poor compaction during the raw clay extrusion process prior to firing.

Performance of brick in the field is a result of both material properties and resistance to micro-climates within the brick’s capillary void structure which cannot be repeated in the lab. Studies have shown a connection between small voids in the material property and susceptibility to longer water retention near the surface. With natural absorption properties, the brick is taking in a small quantity of water in very small pores. 24-hour immersion results are very low (7.5%). Publication of more in-depth studies correlates maximum saturation values for brick with low 24-hour immersion values. The effect of low immersion values and small quantities of absorbed water may increase the susceptibility in brick with small pore structure to freeze thaw failure.

The presence of salt migration out of the mortar and into the brick, plus small pore structure and low immersion values, combining with a cleavage plane resulting from manufacturing are contributing to the Grant High School brick spalls. Brick with smaller pores are less capable of absorbing the expansive forces of freezing water and drying salts. Interlaced pores creating linear plains parallel with the face of the brick create stress failure points resulting in surface spalling. Since the characteristics of the brick resulted from the firing and manufacturing process, the brick will remain susceptible to the failure mechanisms.

Field observations of masonry failures generally correspond with known failure mechanisms. However, it is not unusual that further analysis is necessary to confirm in-field performance and that typical laboratory test results are in conflict with in-situ performance.

The best corrective action is to minimize the amount of surface water and proper mortar joints and mortar composition. Additional spalls are likely to occur in the future due to the accumulation of expansive forces over a long period of time. Replacement of the spalled bricks is recommended over further patching. Leaving spalled brick in place will continue to worsen the condition over time and affect adjacent brick.


Written by Peter Meijer, AIA, NCARB, Principal