Barry Hardman’s scientific contributions

The moisture performance of building envelope systems are strongly dependent on the materials used, the workmanship, and the exposure loads from the interior and exterior environments. The authors have long recognized the need to include the effects of exterior cladding ventilation in the predictive capability of software tools used for hygrothermal analysis. Exterior cladding ventilation has been studied, but no conclusive recommendations have been generated until recently (Burnett, E., Straube, J., and Karagiozis, A., “Synthesis Report and Guidelines,” ASHRAE TRP-1091 Report No. 12, Nov. 2004). While the physics describing the thermal and moisture transport in the presence of air convection is understood, the pressure dynamics is still somewhat qualitatively known. With the addition of new literature data and available field generated monitored data, a simplified model for the wall air cavity ventilation was developed. The scientific approach followed initially included the benchmarking of multi-dimensional advanced hygrothermal model with laboratory and field data. The flow was understood for a wide range of exterior loadings, and once this was completed, an attempt to reduce the complex three-dimensional air flow characteristics into a simple one-dimensional analogue was made. The paper describes how this important feature was included into the WUFI-4.1 software. The paper also describes how users may employ this feature in hygrothermal designs to investigate the advantages and disadvantages of cavity ventilation. Results are also presented on the hygrothermal performance of two walls, one ventilated and the other is unvented. Results show that major differences were predicted and the wall with the ventilation cavity dried out nearly five times faster than the wall without the ventilation. Field monitored stucco wall systems with and without cavity ventilation are also included compared to the prediction provided by the hygrothermal model. Good agreement is shown between the field and WUFI 4.1 model.

Current standardized practices for window and door installation methodologies are typically based on fenestration products that feature integral flanges that form a continuous surface to mount and integrate the fenestration product to the water resistive barrier (WRB)/drainage plane of the wall. While these types of units form the majority of fenestration products available, there are several "non-integral" flange type systems that are also utilized in the construction industry. These include "brick-mold" windows and doors, field-applied flange windows, and non-flanged "box" windows. Due to the discontinuity between the mounting system and the window frame, these types of fenestration systems pose special challenges to achieve a robust, continuous, and water-resistant integration between the fenestration product and the wall, which is not adequately addressed by ASTM E2112, "Standard Practice for Installation of Exterior Windows, Doors, and Skylights" or other standardized methods. The paper describes an installation method for windows and doors with factory-applied brick-mold exterior casings and presents the performance characteristics In laboratory testing of units Installed using the method.

Laboratory water spray testing identifies the performance of a component or assembly under a specified set of simulated wind-driven rain conditions. Well-developed water spray test protocols can also help identify where an assembly is vulnerable to water entry, the test loads at which water entry occurs, and whether the water entry is managed by the installation details in such a way that it does not result in within-wall damage. This paper presents a proposed laboratory test protocol for assessing the effectiveness of wall-window interface details with regard to management of rainwater and provides a rationale for a performance-based approach to the evaluation method. An overview of the test approach is provided, and details of the test apparatus and test specimen are given, including information on implementation of the test method. Examples of testing performed according to the proposed protocol are provided. Finally additional tests for evaluating the performance of installation details are suggested. The additional tests are for field evaluation of installation details and for laboratory evaluation of installation details with regard to the risk of condensation along window frames.

Collaborative efforts over several years resulted in the development of ASTM E2112, “Standard Practice for the Installation of Exterior Windows, Doors and Skylights”. Individuals from the window, sealant, and air barrier industries were involved in the development of the standard. Development of the standard was driven by a desire to reduce water leakage attributed to window installation practices, particularly in residential and light commercial construction. A consensus document addressing the installation of fenestration units in residential and light commercial construction was believed to be needed. While many believe that the development of ASTM E2112 has helped to reduce the prevalence of leaking installations, the Standard, even in its most updated form (ASTM E2112-07), still has significant limitations. This paper addresses some of the limitations of the Standard and is intended to provoke the further development and documentation of installation techniques for a wide array of wall-window combinations that are not yet addressed in ASTM E2112.

Current standards for installation of fenestration units, such as ASTM E2112-07, “Standard Practice for Installation of Exterior Windows, Doors and Skylights” do not address regional considerations, or how the level of wind and rain exposure could influence installation methodology. In the coastal southeastern United States, where extreme wind-driven rain events occur with some regularity, more robust methods than those prescribed in ASTM E2112-07 are necessary. In Florida, single family houses are commonly constructed with surface barrier concrete masonry walls on the first story, and membrane-drainage, wood-frame walls on the second story. This “hybrid” construction is unique, or virtually so, to Florida. Finned windows of a particular design are made expressly for installation in cement masonry unit (CMU) walls as commonly found in Florida homes. The special considerations that relate to residential construction in Florida were of concern to an industrial consortium. The consortium thus formed an Installation Committee to develop methods for fenestration installation that would be applicable to the wall systems commonly found in the coastal Southeast, with consideration of the high wind-driven rain loads that accompany tropical storms. This paper addresses two general installation methods proposed by the Installation Committee, and presents test data for wall assemblies incorporating fenestration units installed using the methods.

This paper will present case studies of condensation damage behind self-adhering membranes installed around windows and other penetrations in exterior walls, as well as case studies of condensation damage behind large interior furnishings installed on the interior surfaces of exterior walls, and in unventilated spaces in Minnesota. The self-adhering membranes that are often used to integrate water-resistive barriers with residential doors and windows can, under certain conditions, lead to condensation and subsequent damage. While wider membranes help prevent inward movement of liquid water to the sheathing and stud framing, they also inhibit outward movement of interior water vapor. By increasing the distance that outward moving vapor must travel, wide membrane flashings trap moisture that can condense in cold climates and cause deterioration of degradable materials. In cold climate regions, condensation damage can also occur in exterior walls behind furnishings such as large mirrors and large cabinets. These interior decorations act as thermal reflectors and prevent interior heat from migrating into the exterior walls. When moisture behind these thermal reflectors is cooled below the dew point, condensation and related deterioration of the wall framing can occur. This paper discusses suggestions for the width of applied self-adhered membranes in cold climate regions and recommends locations for thermally reflecting interior furnishings.

Water intrusion through residential window assemblies is one of the leading causes of damage to the interior. The source is frequently the result of failed seals at window frame jamb/sill intersections or incorrectly installed window flashings. To find the source of and pinpoint the cause(s) of this type of leakage can be destructive, time consuming, and results in high investigation and repair costs. Several instruments can be used to detect and trace water intrusion nondestructively; the most popular are conductive or capacitance-type meters. These meters measure the electrical properties of building materials to indicate wet or dry materials. Often, the readings may be falsely interpreted as an indication of elevated moisture levels when metal is present in the region of the readings. Infrared thermography is successfully being used to detect and trace leakage in building envelopes. Its ability to detect and graphically display heat radiated from a target building area enables an operator to quickly detect leakage with very little interpretation. Although this technology is not new, its use for building envelope diagnostics is new; capabilities in this area are still being discovered. We recently conducted an infrared thermography survey to detect water intrusion at interior window sill regions from failed window frame corner assemblies. The investigative team also used a time-lapse survey to visually track the leakage path. We verified the leak with a capacitance-type meter and through visual observation of materials that became wet from the leak. An infrared thermography survey provides another useful method for quickly and efficiently detecting this type of window leakage.

Architects typically design details for conditions around the perimeter of window openings prior to the final selection of the actual windows used in the building. This requires the architect to make reasonable, general details regarding the attachment of the window frames, the position of the windows in the wall cross-section, and the weathertight details around the perimeters of the windows. Often, once the final selection of the windows has been made, these general details no longer apply or are not sufficiently detailed to clearly reflect the design intent. In some instances, the details for the windows are intentionally shown in a general, approximate fashion, with the assumption that the actual details will be "designed" during the shop drawing phase. However, the shop drawings typically do not accurately reflect all of the conditions surrounding the windows, and the window installation subcontractor understandably does not want the liability of showing or designing all of these details which they will not build and for which they have no responsibility. Further, while the window shop drawings are reviewed by the architect, the purpose of the architects "approval" of the shop drawings is limited. Additionally, shop drawings are not part of the contract documents and, therefore, not part of the design. This results in a common situation where there is no clear basis of design for the weathertightness detailing around the windows. Unfortunately, at present, the authors believe this situation represents the state of the design practice in the building industry. This paper explores common, current practices for designing perimeter weathertightness details for non-flanged windows in commercial applications and how these practices influence the potential for performance problems and water leakage. Suggestions are provided for improvements and alternative methods in design practices. While the paper generally discusses window openings, similar conditions occur at doors.

The most recent model residential building code has been modified to require increased use of water/weather resistive barrier (WRB) materials in construction, and to require some means of draining water from the building enclosure. However, “drainage” performance is not defined, and the Code is unclear about which currently available WRB products and design approaches help provide a durable water-resistant exterior wall enclosure. The present work is a qualitative, “order of magnitude” study of the drainage characteristics of various types of WRB materials (felts, housewraps, drainage wraps, drainage boards, and furring strips), and is a “first step” toward developing an overall durable wall approach for the building enclosure. The ASTM E2273 drainage efficiency test was used in 40 wall assembly mockups to evaluate 11 WRB materials in 8 design configurations. Traditional WRBs and housewraps provided little or no drainage capability to the exterior wall designs tested. Drainage-enhanced housewraps provided an improved level of drainage, but they still retained water. The retained water can migrate through fastener holes to the underlying construction. Best drainage performance was obtained by using WRBs with furring, drainage mats, and profiled sheets (drainage boards). These overall results are in general agreement with similar research by others. These results can guide designers and builders in the proper selection and use of such materials, which should be used as part of an overall durable wall approach to protecting the building enclosure.

An investigation of the evolution of installation methodologies for fenestration products over the past century leads to new conclusions regarding the value of previous installation methodology. In fact, many of the technology developments over this time period have resulted in a decline in the effectiveness of the fenestration products to divert moisture intrusion into buildings. Fenestration systems of the past (before 1910) were uniquely designed to capture and manage the inevitable moisture leaks that occur, either through or around the fenestration product, and skilled craftsman were employed to ensure this effectiveness. The Industrial Revolution, however, brought on the development of complete pre-assembled fenestration products that were then installed into a building opening, without consideration for the specific details of the installation. As a result of this design change, and combined with lower skilled workmanship, moisture intrustion problems involving fenestration products have become chronic. This study uncovers key design and fabrication changes in fenestration technology over this time period that has resulted in this situation. We then present a revolutionary new installation methodology that takes advantage of the water management principles of the past, combined with the fabrication efficiencies of today.