The Building Digests and DBR
  In many ways the Digests document the history of the Division of Building Research and the developments in building science in both Canada and the United States during the 1960's and 1970's, particularly in regard to those subjects directly related to the building envelope.  The Digests were initiated by Neil Hutcheon, Assistant Director of DBR, and were greatly influenced, as was the research program, by his 1953 paper, Fundamental Considerations in the Design of Exterior Walls for Buildings, in which he listed the "major considerations which should be recognized in the design of walls for Canadian conditions".
  These 'considerations' became the 'principal requirements' in his CBD 48 and provided the fundamental basis for building envelope design, or 'building science' as it is thought of today.
  Neil Hutcheon's 1953 paper was mainly concerned with the effects of thermal insulation on increasing the severity of conditions that the exterior portions of a wall had to endure in cold climates, and the problems associated with the wetting and drying of the materials involved.  His example of a wall that would meet the list of requirements was a design concept advocated by Johansson of Sweden in 1946, whereby  a "water repelling screen" be fitted to brick walls to protect them from rain, and that it be applied "so that the water vapour coming from within is automatically removed by ventilation of the space between wall and screen."
  Hutcheon dealt at some length with the potentials causing moisture migration in materials using the problem of efflorescence on bricks as an example to illustrate the movement of moisture in relation to indoor and outdoor conditions, including the effect of solar radiation.
  His approach was influenced by his close connection to the agricultural soil science group at the University of Saskatchewan, the research on moisture and insulation at the Engineering College under his direction, and the activities of the Prairie Regional Station of DBR on insulation and condensation problems in houses.
  The problem of cold weather condensation in houses was also of concern to other  investigators in Canada and the USA, and Hutcheon's Canadian Building Digest 1, Humidity in Canadian Buildings, was an effort to explain the process and the role of indoor humidity using the psychrometric chart.
  Hutcheon's former student, Grant Wilson, was in charge of the Building Services Section of DBR in Ottawa, and based on his studies, contributed CBD 4, Condensation on Inside Window Surfaces and CBD 5, Condensation Between Panes of Double Windows, as illustrative of the factors affecting both surface condensation and concealed condensation.  CBD 5 introduced the role of air leakage and air space convection with the use of the graphical 'stack effect' pressure diagram.
  The problems of efflorescence and rain penetration outlined in Hutcheon's original paper were dealt with by Tom Ritchie of the Building Materials Section in CBD 2 on Efflorescence, CBD 6, Rain Penetration of Unit Masonry and CBD 21, Cavity Walls.  CBD 9, Vapour Barriers in Home Construction, dealt with the materials and methods that could be used to control vapour diffusion and included a cautionary note regarding the possibility of condensation due to outward air leakage.
  In general, only air leakage due to wind had been considered important, and then only in regard to estimating heating loads or natural ventilation.  Although infiltration into the lower floors of multi-story commercial buildings due to stack effect was recognized as a problem in cold climates, the role of air exfiltration in causing condensation was first reported by the Canadians and Norwegians in the 1950's and 1960's.  The first, and still best, technical treatment of the subject is Grant Wilson's CBD 23, Air Leakage in Buildings, issued in 1961.
  Other members of the Building Services Section continued to develop information on windows - Jim Sasaki on the air leakage aspects in CBD 25, Window Air Leakage, while Dick Solvason discussed Sealed Double Glazing in CBD 46, with Grant Wilson rounding out the window work with CBD 58, Thermal Characteristics of Double Windows, with Werner Brown. Another member of the Section, Don Stephenson, was utilizing a variety of analogue and mathematical modelling and calculation techniques to address some of the dynamic and multi-dimensional heat transfer problems that resulted in his CBD 39, Solar Heat Gain through Glass Walls, 47 Extreme Temperatures at the Outer Surfaces of Buildings, 52 HeatTransfer atBuilding Surfaces, and 59 Principles of Solar Shading.  Don Stephenson's colleague, Gint Mitalas, followed his lead and, with the increasing availability of computers, developed the "response factor concept" that forms the basis for the current HVAC Cooling Load and Energy Calculations for large buildings.
  The materials durability aspects began to be addressed by Peter Sereda in CBD 20, Corrosion in Buildings, as his group of physical and organic chemists tackled the fundamentals of moisture in materials and other aspects of material science that had been one of Hutcheon's early concerns.
  CBD 10 Noise Transmission in Buildingsby Tom Northwood, capitalised on the knowledge of the Noise and Vibration Section and was followed by his CBD 41, Sound and People, and CBD 51, Sound Insulation in Office Buildings, aspects of design that had not been included in Hutcheon's 1953 list of requirements.
  CBD 11, Fire and the Design of Buildings, by John McGuire was the first from the Fire Research Section relating to the list of requirements, and was followed by his CBD 33, Fire and the Compartmentation of Buildings.
  CBD 3, Soil and Buildingsby Robert Legget, served as the first contribution of the geotechnical group, while 12, House Foundationsand 29, Engineering Site Investigationsby Carl Crawford and 43, Soil Testingby Bill Eden offered an insight into the specialties of soil mechanics and foundation engineering.  CBD 26, Ground Freezing and Frost Heaving, was by Ed Penner, a graduate of the Soil Science Group at the University of Saskatchewan.
  The Structures Section began their contributions with CBD 18 Strength of Small Roofs, by Schriever and Thorburn, and an introduction to two of their special research interests in CBD 28, Wind on Buildings, 34, Wind Pressures on Buildings, by Alan Dalgliesh and his colleagues, and in CBD 37, Snow Loads on Roofsby Peter and Schriever.
  CBD 13, House Basements, by Bob Crocker, Head of the Construction Section, and CBD 16, Thermal Insulation InDwellings, by Walter Ball, Head of the Housing Section, marked the shift in the CBD's toward larger commercial buildings and the materials used in their construction.  A separate publication series, Housing Notes, was introduced to serve the wood-frame housing industry.

The Building Digests and the Open Rain Screen
  In 1961, DBR had been approached by a general contractor and the federal Department of Public Works to determine the cause of cladding displacement and deterioration on the Lorne Building, an office building in Ottawa which was being operated at high indoor humidities as the National Art Gallery.  It proved to be a classic case, involving window condensation, wall condensation, ice lensing in mortar, spalling of masonry, efflorescence, excessive air leakage, and with previous studies of other high humidity buildings gave emphasis to the warnings in CBD 1 and provided the prime example for Hutcheon's CBD 42, Humidified Buildings.
  The Lorne Building also provided a common focus for the research on condensation, stack effect and air leakage by the Building Services Section, the fundamental studies of the wetting and freezing of materials by the Materials Section, the ice lensing and frost heaving studies by the Soil Mechanics Section, and the analysis of structural movement and deflections by the Structures Section.
  It was at this time that two experienced architects, Kerby Garden and Max Baker, joined the Construction Section and were assigned to study aspects of enclosure design and performance.  Kerby Garden eagerly and rapidly discovered all he could of the wall and window studies of Wilson, Sasaki and Ritchie and proceeded to apply the information, in his own way, to the task.  Max Baker, using a more 'low-key approach', took on the problems of roofs and roofing as his specialty.
  Grant Wilson and his colleagues in the Building Services Section had previously been in close contact with their counterparts in the Norwegian Building Research Institute and Technical University in Trondheim, Norway, in connection with moisture migration research, sealed window performance, and problems of rain penetration and wind-driven rain.  The Norwegian two-stage weather tightening approach was identified as an ideal means to allow expansion and contraction in the exterior cladding by means of unsealed joints, relying on the air tightness of the inner wall to provide the second, unwetted stage.  With its relevance to the 1946 "insulation-on-the-outside" rain screen of Johansson and Hutcheon and as a basis for preventing rain leakage through windows and curtain walls, it became a cornerstone of the DBR marketing strategy, popularised by its description as the "open rain screen", by Kerby Garden in his CBD 40, Rain Penetration and its Control.

The Building Digests and the Building Science Seminars
  Jim Langford, chief architect of the federal Department of Public Works, was instrumental in having DBR present a series of seminars on building science and enclosure design to members of his department in 1963, and encouraged DBR to present these same subjects to the private sector.  The first such seminar, on Exterior Wall Design, was presented in Ottawa and Calgary in 1964 to over 500 attendees, followed by one on Window Design in 1965, and Roof Design in 1966.
  The CBD's were ideal for use as notes and presentation texts for seminars, and this added a new incentive for their development.  Neil Hutcheon updated his original list of requirements with the addition of "Control of light, solar and other radiation" and "Control of Noise" in his CBD 48, Requirements for Exterior Walls.  Another subtle but significant change was made to the original list of requirements - The original, "Control of liquid water flow" was changed to "Control of rain penetration", reflecting the growing interest in the open rain screen approach.
  This was followed by his CBD 50, Principles Applied to a Masonry Wall, in which a wall detail similar to that of the Lorne Building was redesigned to meet the requirements. It also precipitated a growing awareness and interest in the use of construction details as a means of communication.
  The previous CBD's were supplemented by Max Baker's CBD 56, Thermal and Moisture Deformations in Building Materialsfor the Seminar on Wall Design, and Kerby Garden's CBD 55, Glazing Design, and CBD 60, Characteristics of Window Glassadded to those relating to window performance for the Seminar on Window Design in 1965.
  For the Seminar on Roofs, Max Baker had encouraged Don Tibbetts, Head of the Atlantic Regional Station to carry out studies in Halifax that resulted in CBD 65, Mineral Aggregate Roof Surfacing while he contributed CBD 69, Flashings for Membrane Roofing.  Alan Dalgliesh and Bill Schriever gave us CBD 68, Wind Pressures and Suctions on Roofs, Kerby Garden produced CBD 70, Thermal Considerations in Roof Design, CBD 75 on Roof Terraces, and with Peter Jones of the Materials Section, CBD 74, Properties of Bituminous Membranes. CBD 73, Moisture Considerations in Roof Design, considered the implications of moisture as a cause of blister and ridge formation, and based on some studies of sprayed-on insulations at Saskatoon, introduced the concept of seasonal wetting and drying.
  The Head of the Prairie Regional Station had become involved with the Alberta Roofing Contractors Association in the investigation of built-up-roofing failures and had been carrying out studies on roofing assemblies in their new outdoor test facilities.  In addressing a meeting of the Canadian Roofing Contractors Association in Saskatoon, the suggestion was advanced that Hutcheon's principles of wall design could be applied to roofs.  This idea led to the concept of the double drained roof and the protected membrane system as outlined in CBD 99, Application of Roof Design Principles, co-authored with Max Baker.  Although not published before the Seminar, the additional ideas offered in Max Baker's CBD 89, Ice on Roofs and CBD 95, Roofing Membrane Design, were introduced and discussed at the Seminar.
  The Seminars and individual presentations to practitioners across Canada had resulted in the application of the open rain screen in the design of several major projects in Canada and to its  listing as a requirement by at least one major developer.  Its acceptance was clearly evidenced by the number of papers presented by Canadian practitioners at the International Symposium on Weathertight Joins for Walls in Oslo, Norway in 1967.
  During the next five years, the CBD's covered a range of topics not directly related to the building envelope, some being prepared for the Building Science Seminars on Acoustics in 1967, Air Conditioning and Building Design in 1968 and Fire Safety in High Buildings in 1970.
  Kerby Garden presented his CBD's 96, The Use of Sealants, 97, Look at Joint Performance, and 120, Design and Service Life, at the Seminar, Materials, Selection and Durability in 1969, while Ken Latta pursued his interest in applications with CBD 93, Precast Concrete Walls - Problems with Conventional Designs, and its companion 94,  Precast Concrete Walls - A New Basis for Design.
  Meanwhile, members of the Building Services Section were dealing with the problems associated with the thermal breakage of sealed, double glazed windows resulting in Jim Sasaki's CBD 129, Potential for Thermal Breakage of Sealed Double Glazing Unitsand Bill Brown's CBD 132, Glass Thickness for Windows.
  The trend toward high-rise commercial office buildings brought an increased concern for the influence of building stack effect and Grant Wilson and George Tamura pioneered the initial field studies that established the principles outlined in CBD 104, Stack Effect in Buildings, and CBD 107, Stack Effect and Building Design, for the Seminar on Air-Conditioning and Building Design.
  With the other CBD's of this Seminar -  Don Stephenson's CBD 101, Reflective Glazing Unitsand 105, Heating andCoolingRequirements,  Neil Hutcheon's 102, Thermal Environment and Human Comfortand 106, The Basic Air-Conditioning Problem, Dick Solvason's 108, Air- Conditioning Processes and 109, Air Conditioning Systems, and Grant Wilson's classic CBD 110, Ventilation and Air Quality, constitute a collection that should be required reading for all building science practitioners who want to understand something about the building as a system.

The Building Digests and the Building Envelope
  In 1971 most of the past work was brought together and the Seminar on Walls, Windows and Roofs was presented to over 600 attendees at two sessions in Ottawa and one in Calgary.  Max Baker gave us CBD 111, Decay of Wood and 112, Designing Wood Roofs to Prevent Decay, in which he discussed some of the implications of moisture storage.
  The following year, a seminar on Cracks, Movements and Joints in Buildings focused on the design and performance of cladding, in which Klara Karpati's research on sealants, Ken Latta's on construction tolerances, and Gordon Plewes on deflections and structural movements were presented and subsequently published as 155, Joint Movement and Sealant Selection, 171, Inaccuracies in Construction, 125, Cladding Problems due to Frame Movement, and 185, Failure of Brick Facings on High-Rise Buildings.
   Ken Latta's book, Walls, Windows and Roofs for the Canadian Climate, was published by DBR in 1973 as his summary of the basis for envelope design, and in which he considered the environment below grade, the pressure equalisation requirements of the open rain screen and the need for structural support for the air barrier.
  A number of architectural details describing  several successful wall designs, as illustrated by George Keuster, were included as an Appendix.
  By this time it had become difficult to maintain the monthly production of CBD's since many researchers were preoccupied with their own research, and there had been very few new developments in the building envelope field except in regard to built-up-roofing.
  Roofing research at Saskatoon had continued with trials of other insulations in a protected membrane system and Charlie Hedlin and Max Baker eventually published the more definitive CBD 150, Protected Membrane Roofs, and CBD 176, Venting of Flat Roofs, which showed the venting ideas in CBD 99 to be ineffective and possibly a disadvantage.
  Other CBD's dealing with roofing systems were prepared for, or resulted from the Seminar in 1975 on the Performance of Membrane Roofing Systems, such as CBD 179, Inspection and Maintenance of Flat Roofsby Charlie Hedlin and CBD 151, Drainage from Roofsby Max Baker.
  Another important contribution was Dick Solvason's explanation for the ridging, shrinkage and splitting of built-up-roofing membranes in Building Research Note 112, which he based on temperature effects and the unique properties of bitumen, rather than moisture conditions.  It was eventually referenced in Bob Turenne's CBD 202, Joints in Conventional Bituminous Roofing Systems and 211, Bituminous Roofing Membranes - Practical Considerations.
  CBD 228, Sliding Snow on Sloping Roofsby Don Taylor addressed the problem of ice and snow "avalanching" from atriums, but most subsequent CBD's reflected a move back to housing, and the specialties of the Materials, Acoustics and Fire Research Sections.

The Building Digests and Air Leakage
  The energy crisis of 1973 led to a corresponding shift in the activities of the Division which were reflected in the Seminars of this time.  The early CBD's still provided much of the basic information but the presentations were geared to the prevailing interests and published later as Seminar Proceedings.
  Air tightness as an energy conservation measure gained renewed attention and the critical junction between walls and roofs in buildings was singled out for attention in the 1977 Seminar on Construction Details for Air tightness.  In 1982, a Seminar on Exterior Walls - Understanding the Problems, involved a revival of the old design principles but placed even greater emphasis on air leakage as the main source of condensation and deterioration in masonry walls.  In 1984, in the seminar, Performance of Materials in Use, air leakage was again highlighted, the specific problems of stone façades and parking garages dealt with, and an update provided on coatings, adhesives and sealants.
  In 1986, the Seminar, An Air Barrier for the Building Envelope, introduced the concept of the air barrier as a separate component and as a system, with an effort made to establish the limiting air leakage rates for an "effective air barrier", as required in the new Part Five of the NBC.  The structural loading of the "air barrier" and its role in creating a "pressure equalized air space" to prevent rain penetration were also stressed, and this led to a revival of research and technical dissertation on this component as a singular, multi-purpose element of the building envelope. This revival was due, in part, to the trend toward steel stud back-up for masonry walls in commercial buildings where wood-frame wall construction practices tended to be followed.  The indiscriminate use of polyethylene film as the air-vapour barrier raised questions about its durability under the pressures due to wind and prompted tests which, to some of us, seemed not entirely relevant.
  Discussions on the differences between an air and vapour barrier were quite reminiscent of those in CBD's  9, 23, and 42, with suggestions for an "air barrier on the outside" violating the old principles of venting and drainage for the control of condensation and neglecting air space convection as discussed in CBD 5 and 16.  Even the 'airtight drywall' (ADA) system could be said to have been suggested in CBD 42, and the placement of an unbroken, impermeable film or coating under exterior insulation on the outer surface of the back-up wall reiterated the advice given in CBD's  50 and 57.

The Building Digests and Subsequent Publications
  The Canadian Building Digests continued to be used as primary references by most authors of books and papers dealing with the building envelope, using their own individual expertise and experience to apply them to their particular area of interest.
  Max Baker organised the CBD's and other publications that dealt with roofing in his book, Roofs: Design Application and Maintenance in 1980 using his knowledge of the roofing industry and its practices, and his architectural and civil engineering design and teaching experience.  He was also the first to expand on the seasonal "drying to the inside" concept of CBD 73 using a graphical technique based on the monthly annual outdoor temperature.
  The CBD's were also used as a basis by Gordon Plewes in applying his practical experience and understanding of structural design to produce the document, Exterior Wall Construction in High-Rise Buildings, for Canada Mortgage and Housing Corporation in 1981.
  Ron Brand, an architect and leading teacher of building science in architecture at Carleton University, had been particularly interested in the use of construction details to illustrate building envelope design principles and used this as a feature of his doctorate thesis submission to the University of Montreal.  His illustrations were subsequently published in his book, Architectural Details for Insulated Buildings, in 1989, and comprise a unique collection of details linked to explanatory text.
  The information in the CBD's of the 1960's and 1970's also formed a focus for many of the chapters of Neil Hutcheon's book, Building Science for a Cold Climate, published by DBR in 1983, where he dealt with the basic science underlying the principles, discussed the derivation of  equations used in their development, and the fundamentals of control of the indoor environment.
  The sections on moisture expand his early treatment of moisture in materials and his heating, ventilating and air-conditioning interests are evident in the discussion of air leakage, ventilation and the indoor environment.  The listing of requirements in CBD 48 are applied to the building as a whole, and in dealing with the performance of the exterior envelope, emphasis is placed on the effect of the arrangement of materials and components on their individual environment, the seriousness of wetting under cold weather conditions and the control of air leakage to control condensation.
  Specific recommendations include - the placement of both air and vapour barriers "where the temperature is above the dewpoint of the indoor air", that "air exchange between the two sides of insulating layers must be prevented" and that "protection against the effects of any condensation that does take place can be provided by features that allow drainage or drying or both."
  In 1996, the co-author of the book, after twelve years of teaching and exposure to the private sector world of construction and consulting, also used the CBD's as a principal resource and reference for a self-study course that attempted to provide a more practice oriented approach in the application of building science to the building envelope.
  The concept of seasonal wetting and drying, as mentioned in CBD 9 and in CBD 73, and introduced by Max Baker in his book, Roofs: Design Application and Maintenance, led to the development of a graphical method for predicting the seasonal moisture performance of walls in a paper to ASHRAE in 1985, which was translated into a designer-oriented computer program by Louis Reginato in 1989, and promoted as a spreadsheet method in 1996.
  The vertical pressure diagram introduced in CBD's 104 and 107 has been used universally as a means to explain building stack effect, and as applied in CBD's 133 and 134 was fundamental to the development of measures for fire safety and smoke control in the National Building Code.  It has been employed in recent years to the analysis and prediction of air movement in high-rise apartment buildings where the effect of internal separations is markedly different than in open plan high-rise office buildings.  Such analysis suggests that the airtighness of internal doors and separations is more important in regard to energy conservation, the operation of HVAC systems and occupant satisfaction than the sealing of exterior walls and windows.  The basis for this analysis originated from the recommendations in CBD 23 in regard to the influence of internal separations.
  A Building Digest should have been written to bring more attention to the information in DBR Technical Paper 445, Wind-Driven Rain and Buildings, by Gordon Robinson and Max Baker.  It provides graphic, observation based information as to the patterns and paths that wind-driven rain can follow on the façades of buildings which challenges the acceptance of air leakage as the exclusive cause of masonry failures.
  Another CBD should have dealt with the problem of reversed vapour diffusion due to solar heating, as reported in 1966 by Grant Wilson in DBR Technical Paper No. 226, Condensation in Insulated Masonry Walls in Summer.  It was discussed at the Seminar on Walls, Windows and Roofs in 1971, and has been referenced in several publications since that time including the ASHRAE Fundamentals Handbook, Building Science for a Cold Climate and the recent ASTM Manual on Moisture Control in Buildings.  It was the subject of a past presentation to ABEC entitled, Don't Discount Diffusion, and is dealt with in detail in the self-study course previously mentioned.
  The process has been accepted as a primary cause of mould and mildew problems in steel-stud masonry walls of buildings in the hot and humid climates of the southern states, both in the ASTM Manual and in the Moisture Control Handbook authored by Joseph Lstiburek.  This solar reversal problem has also been recently rediscovered by researchers in a test hut at the University of Waterloo and is being cited as one cause of the current moisture problems in stuccoed wood-frame walls in Vancouver.
  The "dynamic buffer zone" as an approach to the condensation problems in high humidity buildings, is reminiscent of the suggestion in Neil Hutcheon's original paper in 1953 as well as in his CBD 1, Humidity in Canadian Buildings.  It is also similar in principle to a feature used by Canadian architect Ernest Cormier in the design of the federal government printing plant in Hull, Quebec and in the clerestory windows of his house in Montreal.  Another example is the DBR Building Services Building, built in 1970, which was designed by members of the Division with a deliberate floor layout that put the researchers offices at the perimeter as a "buffer zone" to outdoors for the temperature and humidity controlled interior laboratories.
  The aluminium framed windows of the offices also employed the fin effect - with greater surface area exposed to the indoors, as suggested in CBD 44.  The walls of the building were designed as an open rain screen, as described in the Appendix to Ken Latta's book, and, using steel studs and glass fibre batts on the exterior of a concrete block wall, probably represented one of the first exterior insulation finish systems in North America.

The Building Digests Past, Present and Future
  Over the years, DBR and its successor, IRC, have periodically considered the need for their revision and updating or the adoption of new techniques for increasing their use and application.
  With the acceptance of SI, consideration was given by DBR as to whether the CBD's should be reviewed, revised and converted to metric units but the effort and costs were not justifiable.  Earlier in their history, the possibility of marketing them in the USA on a subscription basis was considered, but the costs of postage and the difficulty of maintaining production discouraged that venture.  However, advantage was taken of the computer based techniques of the NRC Library (CISTI) and the Technical Information Service (TIS) to create an index for the CBD's and to investigate computer based searching techniques.  This gave those involved an appreciation of the significant difficulties in key word searching and classification by computer, similar to the problems on the Internet today.
  In those days the high percentage of unchecked, unreliable or useless information even in the reviewed literature led some experienced researchers to search on the basis of their judgment, avoiding authors, publications, and research agencies they knew and distrusted.  Knowledgeable, generalist reviewers were hard to find and problems in retrospective searching by computer were hampered by the need to input archival information by hand.
  Although the selection problem persists or is worse today, the manual input of information is no longer a problem and it would be possible to scan selected Digests, to classify them and offer them on the Internet, with links to background papers and problems or subjects of current  interest.  There are any number of experienced building science practitioners in the private sector who would be able to offer suggestions on format, updating, or conversion to SI, many of whom are associated with the Building Envelope Councils.  An added advantages of the CBD's is that they are available in French, and since almost all of them are in Imperial Units, would have a particular appeal to practitioners in the United States.
  Whether their availability on the world wide web would induce more people to read them is unknown, since the preference by most people in the industry for new information and new research seems to overshadow any interest in past publications or ideas.
  It was once suggested that one problem in transferring technology in the building industry is that nobody reads anything. It may be equally valid today since practitioners, as well as many researchers in building and construction seem to have neglected to read or re-read the CBD's, even those that fall into their respective areas of interest.

Gustav Handegord 1998/01/30  Back to ABEC South Newsletter