ABSTRACT Many changes to the International Residential Code are related to building envelope design recommendations based on recent climate zone designations provided by the International Energy Conservation Code. The building science technical community has long recognized the influence of temperature, precipitation, and humidity on building envelope performance, as well as material selection and placement in the assembly. Historical construction practices regarding interior vapor retarder use and placement, air barrier specifications, roof system ventilation, and crawl space venti¬ lation have changed from traditional recommendations to practices not allowed until recently. The purpose of this paper is to provide an overview of the building envelope research and analysis conducted to support the various changes to the code language. Vapor retarder and air barrier requirements will be reviewed, as well as the allowance of unvented attic and crawl space assemblies. A thorough technical literature review detailing issues related to energy efficiency, moisture management, and building envelope performance will be discussed. SPEAKER Stanley D. Gatland II is the manager of building science technology for CertainTeed Corporation. He is responsible for generating and providing technical information to architects, engineers, builders, trade contractors, building envelope consultants, building scientists, and building code officials on the system performance of new and existing building envelope materials, He is also in charge of building science educa¬ tional training. Gatland has expertise in the areas of building science and architec¬ tural acoustics, with an extensive national and international network of professional contacts in the fields of building science, energy efficiency, heat and moisture trans¬ fer, environmental acoustics, and fire performance. He is a graduate of the University of Massachusetts at Amherst with both bachelor and master of science degrees in mechanical engineering and is an active member of ASHRAE, ASTM, ASME, and BETEC. CONTACT INFO: stanley.d.gatland@saint-gobain.com and 610-341-7152 Gatland – 44 Proceedings of the RCI 24 th International Convention Building Science’s Influence Over the Building Codes ABSTRACT Many changes to the International Building Code (IBC) and International Residential Code (IRC) are related to building envelope design recommendations based on recent climate-zone des¬ ignations provided by the Interna¬ tional Energy Conservation Code (IECC) and the American Society of Heating, Refrigerating and Air- Conditioning Engineers (ASHRAE) Standard 90.1. The building sci¬ ence technical community has long recognized the influence of temperature, precipitation, and humidity on building envelope performance, as well as material selection and placement in the assembly. Historical construction practices regarding interior vapor-retarder use and place¬ ment, air-barrier specifications, and roof-system ventilation have changed from traditional recom¬ mendations to practices not allowed until recently. The purpose of this paper is to provide an overview of the build¬ ing envelope research and analy¬ sis conducted to support the vari¬ ous changes to the code language. Vapor-retarder and air-barrier requirements will be reviewed, as well as the allowance of unvented attic and cathedral roof/ ceiling assemblies. A technical literature review detailing issues related to energy efficiency, moisture man¬ agement, and building envelope performance will be discussed. In addition, the concept of hygrothermal analysis will be presented as a method for predicting build¬ ing envelope performance. Figure 1 – Average minimum air temperature based on annual climatology data between 1971 and 2000 (Copyright © 2004, Spatial Climate Analysis Service, Oregon State University, www.ww.ocs.oregonstate.edu/prism. Map created Feb 20, 2004.) INTRODUCTION – CLIMATE CONSIDERATIONS New climate classifications proposed by Briggs et. al (2003), were incorporated into the 2003 IECC and ASHRAE Standard 90.1 (ASHRAE 2004). The changes cat¬ egorize the U.S. into several hygrothermal regions, which take into account exterior air tempera¬ ture, relative humidity, and pre¬ cipitation. Historical geographic weather data were used to define air temperature extremes that determine energy efficiency requirements (Figure 1). In addition, historical precipi¬ tation data were used to further define moisture-related building envelope requirements (Figure 2). Lstiburek (2002) categorized North America into several hygrothermal regions, which take into account exterior tempera¬ ture, relative humidity, and pre¬ cipitation. The combination of geographical weather information creates a climate zone map (Figure 3). Generally speaking, building envelope design in cold and extreme cold climate zones focus¬ es on heating systems, while building envelope design in hot/ dry and hot/ humid climates focuses on air conditioning sys¬ tems. These climate zones also dictate how construction must focus on moisture loads and in keeping moisture out of buildings. Areas labeled “mixed” experience both hot and cold climates and often can be heating- or cooling- Proceeilings of the RCI 24th International Convention Gatland – 45 Figure 2 – Average precipitation based on annual climatology data between 1971 and 2000 (Copyright © 2004, Spatial Climate Analysis Service, Oregon State University, www.ww.ocs.oregonstate.edu/prism. Map created Feb 20, 2004.) Figure 3 – United States climate zone designations. (Source: DOE Building America Program.) Figure 4 – IECC 2003 climate zone map. dominated. The IECC (2003, 2006) and ASHRAE Standard 90. 1 (2004) climate zone maps divide the continental United States into seven climate zones for energy efficiency and moisture control. Regions of Alaska are considered climate zone 8. The purpose of this paper is to provide an overview of the build¬ ing envelope research and analy¬ sis conducted to support the vari¬ ous changes to the code language. Vapor-retarder and air-barrier requirements will be reviewed, as well as the allowance of unvented attic and cathedral roof/ ceiling assemblies. VAPOR RETARDERS Water vapor will move or dif¬ fuse through building materials when areas of high vapor pres¬ sure and low vapor pressure exist on opposite sides of that material. The movement is from the highvapor pressure side to the lowpressure side (Figure 5). Histor¬ ically, two North American build¬ ing codes – the International Code Council (ICC 2003) and the National Building Code of Canada (Canadian Commission on Build¬ ing and Fire Codes 2005) require that vapor retarders have a water vapor permeance of 1 perm or less when tested in accordance with the American Society for Testing and Materials (ASTM) standard test method ASTM E 96 (2005) using standard, diy-cup condi¬ tions of 0 and 50 percent relative humidity, creating a mean relative humidity of 25 percent (Figure 6). Gatland (2005) presented ex¬ perimental water vapor perme¬ ance results for several common interior building materials over a wide range of mean relative humidities. Figure 7 displays a simplified version of the data between 25 and 95 percent. The permeance data were plotted on a log scale in order to visualize the differences between materials. If building materials are placed into Gatland – 46 Proceedings of the RCI 24th International Convention Figure 5 – Concept of water vapor diffusion. four categories with respect to water vapor permeance, vapor barrier (0.1 perm or less), vapor retarder (1 perm or less), semipermeable (1 to 10 perms), and permeable (greater than 10 perms), then products can be described as fitting into one or several categories. Historically, interior vapor retarders were required in many of the mixed heating- and coolingdominated climates (Figure 3) of the U.S. In 2003, the IRC and the IECC adopted changes to interior vapor retarder requirements based on numerous U.S. Depart¬ ment of Energy-funded research programs and the support of the building science technical com¬ munity. After 2003, climate zones 1 through 3, 4A, and 4B, would not require an interior vapor re¬ Figure 6 – ASTM E 96 cup test samples. tarder (see Figure 8). Building en¬ velopes in climate zone 4C (the Pacific Northwest) would still require an interior vapor retarder, based on research conducted on various wall assemblies located in the Seattle, Washington, region (Tichy et. al, 2003; Gatland et. al, 2007). Joint research conducted by Pennsylvania State University, Oak Ridge National Laboratory, and the University of Waterloo examined the benefits of ventila¬ tion spaces between wall claddings and water-resistive bar- Figure 8 – IECC (2003) interior vapor retarder requirements – climate zones 4C, 5, 6, 7, and 8. Vapor Barrier Vapor Retarder Seml-permeable ■ 6 mil Polyethylene (0.05 ■ 0.06) ■ Asphalt Coated Kraft Paper (03-3) ■ 2 mil polyamide film p. 8 – 36) ■ Latex Primed anc Painted Gyp. Bd. -1 &2 Cods (3 – 35) ■ Latex Primed Gypsum Board -1 Coat (22 – 66) ■ Plan Gypsum Board (45 – 86) Figure 7 – Common interior building materials’ water vapor permeance range. riers in wood-framed wall assem¬ blies (Burnett 2004). Based on this research and numerous hygrothermal simulations of wall assemblies with variations on cladding type, cladding ventila¬ tion, and exterior sheathing type (Karagiozis and Desjarlais, 2005) in geographic locations covering all of the climate regions in the continental United States, Lstiburek (2004) proposed changes to the 2006 IECC that provided min¬ imum interior vapor retarder requirements dictated by wall design. Section 402.5 “Vapor Retarder Class” of the proposed 2006 IECC Proceedings of the RCI 24th International Convention Gatland – 47 Table 1 – 2006 IECC Table 402.5.1, Class III vapor retarders. Climate Zone Allowance of Class III Vapor Retarder Marine 4 Vented cladding over OSB Vented cladding over plywood Vented cladding over fiberboard Vented cladding over gypsum Insulated sheathing with R-value > R2.5 over a 2 x 4 wall Insulated sheathing with R-value > R3.75 over a 2 x 6 wall 5 Vented cladding over OSB Vented cladding over plywood Vented cladding over fiberboard Vented cladding over gypsum Insulated sheathing with R-value > R5 over a 2 x 4 wall Insulated sheathing with R-value > R7.5 over a 2 x 6 wall 6 Vented cladding over fiberboard Vented cladding over gypsum Insulated sheathing with R-value > R7.5 over a 2 x 4 wall Insulated sheathing with R-value > RI 1.25 over a 2 x 6 wall 7 and 8 Insulated sheathing with R-value > RIO over a 2 x 4 wall Insulated sheathing with R-value > RI 5 over a 2 x 6 wall BUILDING ENVELOPE AIR¬ TIGHTNESS Unrestricted flow of air against or through a building can have an enormous im¬ pact on the build¬ ing’s temperature and energy effi¬ ciency. In cold months, warm air leakage to the ex¬ terior and thrust of cold winds against the exte¬ rior surface of a building can cause interior temperatures to lower, requiring extra work from the heating sys¬ tem and addition¬ code language classifies vapor retarders into three categories: I (0.1 perm or less), II (0.1 to 1.0 perm), and III (1.0 to 10 perm). See Figure 7. Vapor retarders are classified using the ASTM E 96 desiccant method or Procedure A. Class I and II vapor retarders are required in climate zones 4C, 5,6, 7, and 8. Exceptions are provided for basement walls, below-grade wall sections, and construction in which moisture or freezing condi¬ tions will not damage the building materials. Guidance is provided for the allowance of Class III vapor re¬ tarders when design conditions exist that promote drying through the use of ventilated claddings or reduce closed-cavity condensa¬ tion potential through the use of exterior insulating sheathings. One acceptable Class III vapor retarder would be latex-painted, interior gypsum board. Table 1 summarizes the climate-zone-specific combinations of vented clad¬ dings, exterior sheathing materi¬ als, and insulated sheathings that permit the use of Class III vapor retarders. Vented claddings include vinyl lap or horizontal aluminum siding applied over an approved weath¬ er-resistive barrier. Additional claddings, such as brick veneer, require a 1- to 2-inch clear air¬ space with vented openings as specified by Section R703.7.4.2 of the IRC. al utility bills to keep the interior warm. The same is true with cool air leakage and warm air intrusion in summer months. Like heat flow, air flow has a strong impact on the build¬ ing envelope. Air flow occurs only when there is a difference between the exterior and interior of a building. Air will flow from a region of high pressure to one of low pressure — Maximum Air Infiltration Rate (cfm/ft2 @ 0.30 in. of water or 75 Pa) Material Assembly WholeBldg Energy Code Requirement astme2izs astmeiszz astmezzs ASHRAE 90.1 -2005 0.004 0.04 0.4 Federal Guidelines – 2003 0.004 Wisconsin – 2003 0.06 Massachusetts -2001 0.004 The National Building Code of Canada -1995 Table 2 – Summary of commercial building air barrer requirements. Gatland – 48 Proceedings of the RCI 24th International Convention the bigger the difference, the faster the flow. Air-pressure dif¬ ferentials are thus the driving force behind air flow. There are three air-pressure differentials — wind pressure caused by external forces, stack pressure created by warm air rising, and mechanical pressure created by a building’s mechanical systems. Designing an airtight building envelope is extremely important to a building’s performance. Also, adaptive reuse and building reno¬ vation projects require special considerations to meet airtight¬ ness challenges. Airtight building envelopes help control heat and sound energy, as well as airborne moisture flow and airborne conta¬ minants. Airtight building enve¬ lopes even help to control the spread of fire if cavities are prop¬ erly blocked. In short, airtight building envelopes create more energy-efficient, healthy build¬ ings, which are more durable and require less maintenance. The best way to make an airtight building envelope is by incorpo¬ rating an air barrier system into the building envelope. A building material must meet a range of requirements before it can be approved as an air barrier. The most important requirement for air barriers is air impermeabil¬ ity, or not allowing any air to pass through it. Air barrier systems must also be continuous, as well as strong and durable, to stand the test of time and weather of all kinds. Air barriers installed on the exterior of buildings must be able to withstand ultraviolet light in addition to precipitation, freezing, and thawing. Figures 9A and 9B – Air exfiltration through suspended acoustical ceiling that penetrates the building envelope at the roof parapet and wall interface (9A) causes airborne moisture to deposit at the roof-wall intersection, creating icicle formation during the winter season (9B). ASHRAE 90.1-2004, Section 5.4.3 – “Air Leakage,” describes how to seal the building envelope to minimize air leakage. Areas highlighted for treatment are joints around fenestration and door frames, building envelope intersections (walls, foundations, structural floors, building cor¬ ners, roofs), building envelope utility penetrations, site-built fen¬ estration and doors, buildingintegrated ducts or plenums, vapor retarder discontinuities, and all other openings in the building envelope. ASHRAE 90.1 has code-specific requirements for the material alone, the material in an assembly, and for the whole building (Table 2). Many of the recommendations are based on research (Anis et. al, 2005, Em¬ merich et. al, 2005) and specifica¬ tions from the Air Barrier Association of America Proceedings of the RCI 24 th International Convention Gatland – 49 (www. airbarrier, org) . When the goal is to control air flow, efforts should be made to compart¬ mentalize the build¬ ing as much as possi¬ ble. The purpose of compartmentaliza¬ tion is to isolate con¬ necting spaces and minimize the impact of the stack effect. Disconnect occupied building spaces from the foundation and the roof, as well as rooms next to con¬ necting corridors. Effective air barriers require special attention at all penetra¬ tions. Areas of discontinuity in the building are where many problems can begin. These include roof decks and parapets, windows and doors, wall and floor intersections, at expansion joints, wherever there are brick ties, and at all fapade supports. Figure 9 shows an example of what can happen when air exfil¬ tration carries moisture through poorly sealed crevices in a build¬ ing all the way to the roof parapet, causing ice damming at the top. The 2006 IECC, Section 402.4.1 – “Building thermal enve¬ lope,” describes how to seal the building envelope to limit infiltra¬ tion. Many of the requirements duplicate specifications outlined in ASHRAE 90.1. Special consid¬ erations are described for residen¬ tial applications, such as dropped ceilings or chases adjacent to the thermal envelope, knee walls, building envelopes separating the garage from conditioned spaces, tubs and showers on exterior walls, multfamily dwelling com¬ mon walls, and attic hatches. Figures 1OA and 1OB – Snow melt on roof due to air leakage (left) and cathedral ceiling surface staining (below) due to surface con¬ densation on the light fixture from airborne moisture transport. Common problems with the roof/attic ceiling system are condensa¬ tion and sur¬ face staining. Figure 10 illus¬ trates the prob¬ lems that occur with an airleaky, uninsu¬ lated recessed light. Roof snow melt (10A) is a symptom of a heat transfer problem due to air movement and the lack of thermal insula¬ tion. Condensation accumulating on the light fixture due to air¬ borne moisture transport runs down the slope of the cathedral ceiling, pooling and creating stains at the seams (10B), which is visible to the inside. UNVENTED ROOFING SYSTEMS As the sizes of homes have increased over the years, tradi¬ tional attic ventilation has become more and more difficult to achieve, due to architectural details that include open attics, vaulted ceilings, and cathedral Gatland – 50 Proceedings of the RCI 2 4th International Convention ceilings (Figure 11). TenWolde and Rose (1999) described the climate-based hygrothermal perfor¬ mance issues re¬ lated to traditional ventilation tech¬ niques. Subse¬ quently, the U.S. Department of En¬ ergy’s Building Am¬ erica Program fund¬ ed many research projects related to identifying and mea¬ suring the perfor¬ mance benefits of constructing unvented attic applica¬ tions in warm / humid, warm/dry and mixed /dry cli¬ mates (Hendron et. al, 2003; Parker, 2005; Lstiburek, 2006). Quarles and Figure 11 – Difficulties creating traditional attic ventilation. TenWolde (2004) ex¬ amined the implications of attic ventilation for homes located in urban wildlife areas at risk for for¬ est fires. The Florida Solar Energy Center (Parker 2005) evaluated the impact and need for attic ven¬ tilation in Florida homes through a very extensive and thorough technical literature review. In 2003, the International Residential Code adopted lan¬ guage allowing unvented attic¬ assembly design strategies. Sec¬ tion 806.4 – “Unvented attic as¬ semblies” – describes the space between ceiling joists of the top story and the roof rafters as the attic area. Unvented attic assem¬ blies require that the space is completely contained within the building thermal envelope (Figure 12). No interior vapor retarders are installed on the ceiling side (attic floor) of the unvented attic assembly. Wood shingle or shake roofs require a minimum %-in vented air space between the Figures 12A and 12 – Warm- and humid-climate, air-impermeable insu¬ lation at the underside of roof-deck application (above). Warm- or mixedand dry-climate, air-permeable insu¬ lation at the underside of tile roof deck application (right). Proceedings of the RCI 24th International Convention Gatland – 51 Climate Zone Minimum Rigid Board or Air- Impermeable Insulation R-value 2B and 3B tile roof only 1A, 2A, 2B, 3A, 3B 4C 4A, 4B 5 6 7 8 0 (none required) R-5 R-10 R-15 R-20 R-25 R-30 R-35 Table 3 – 2003 IRC Table R806.4, Insulation for Condensation Control. shingle or shake and the roofing underlayment above the roof deck. The unvented attic assembly requires that air-impermeable insulation be installed directly under the structural roof sheath¬ ing. In climate zones 5, 6, 7, and 8, any installed air-impermeable insulation is required to be a vapor retarder or have a vapor retarder coating or covering in direct contact with the underside of the insulation. Hybrid insulation systems that include both air-imperme¬ able and air-permeable insulation require that the air-impermeable insulation’s thermal resistance (R-value) be great enough to con¬ trol condensation at the air¬ regions of the country. One of the reasons for the system’s success is that dry climates are much more forgiving than humid envi¬ ronments. In addition, interior air -barrier systems, typically con¬ sisting of continuous, smart, vapor retarder or polyethylene films, combined with finished gyp¬ sum-board ceilings are necessary for the assemblies to perform sat¬ isfactorily (Figure 13). Many of the regional building-code officials require transient heat and mois¬ ture transfer (hygrothermal) analysis of each unvented cathe¬ dral ceiling assembly to predict the acceptable long-term perfor¬ mance of the system with respect to moisture management. and published in recent years. Hygrothermal analysis predicts the impact of tran¬ sient heat and moisture trans¬ fer on building envelopes over time. It may be used in plan¬ ning construction projects and on existing buildings with moisture problems. Special¬ ized software helps the user visualize such factors as sur¬ face condensation and mold growth potential, the wetting and drying potential of the building envelope, and the moisture content of building components. This analysis helps building designers evaluate po¬ tential preconstruction moisture risks and also helps analyze and solve moisture problems after construction. The resulting re¬ ports should conform to ASHRAE 2006, Standard 160 P, “Design Criteria for Moisture Control in Buildings.” Hygrothermal analy¬ sis takes into consideration both the geographic location and the building’s orientation. Vapor re¬ tarder and unvented roofing sys¬ tem building-code language changes previously discussed were supported by hygrothermal modeling (Karagiozis and Desjarlais, 2005; Lstiburek, 2006). impermeable surface throughout the year. The air -impermeable insulation shall be applied in direct contact to the underside of the structural roof sheathing. Table 3 outlines the minimum thermal resistance necessary for condensation control in all cli¬ mate zones for hybrid insulation systems. The air-permeable insu¬ lation shall be installed directly under the air-impermeable insu¬ lation. Unvented cathedral-roof/ ceiling assemblies are not covered by the recent code language. The application has become a com¬ mon design option in many of the cold/dry and extreme cold/diy HYGROTHERMAL ANALYSIS When designing a building envelope, one of the best tools for predict¬ ing its moisture manage¬ ment performance is hygrothermal analysis. A large amount of research related to developing tran¬ sient heat and moisture transfer (hygrothermal) analysis methods (Trechsel, 2001; Straube et. al, 2001) and measuring the hygrothermal properties of building materials (Hens et. al, 1996; Kumaran, 2001; ASHRAE, 2005) has been conducted Figure 13 – Airtight unvented cathedral- roof/-ceiling assembly with airpermeable insulation in an extreme cold and dry climate. Gatland – 52 Proceedings of the RCI 24th International Convention CONCLUSION Building science technology and practices will continue to influence changes to future build¬ ing envelope design and energy efficiency code requirements. As more and more tools are devel¬ oped, such as hygrothermal analysis software, we will develop a greater understanding of the dynamic relationships among the building envelope, the occupants, the mechanical systems, and the surrounding environment. Inte¬ grating products and systems that help control heat, air, and moisture transport in the building envelope will ultimately create more energy-efficient, comfort¬ able, durable, and sustainable buildings. REFERENCES W. Anis, “Commissioning the Air Barrier System,” ASHRAE Journal, March 2005. ASHRAE, Handbook, of Funda¬ mentals, “Chapter 23 – Thermal and Moisture Control in Insulated As¬ semblies: Vapor Retarders,” American Society of Heat¬ ing, Refrigerating, and Air- Conditioning Engineers, Atlanta, 2005, pp. 23.18- 23.19. ASHRAE, Handbook of Funda¬ mentals, “Chapter 25 – Thermal and Water Vapor Transmission Data,” Amer¬ ican Society of Heating, Refrigerating, and Air- Conditioning Engineers, Atlanta, 2005. ASHRAE Standard 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings,” American Society of Heating, Refrigerating, and Air-Conditioning Engi¬ neers, Atlanta, 2004. ASHRAE Standard 160P, “Design Criteria for Mois¬ ture Control in Buildings,” Working Draft 2006-2, American Society of Heat¬ ing, Refrigerating, and Air- Conditioning Engineers, Atlanta, March 2006. ASTM E 96-05, “Standard Test Methods for Water Vapor Transmission of Materials,” 2005 Annual Book of ASTM Standards, Vol. 04.06, American Society for Test¬ ing and Materials, West Conshohocken, PA, 2005. R.S. Briggs, R.G. Lucas, and T.Z. Taylor, “Climate Class¬ ification for Building Ener¬ gy Codes and Standards: Part 1 – Development Pro¬ cess,” ASHRAE Winter Meeting, 2003. R.S. Briggs, R.G. Lucas, and T.Z. Taylor, “Climate Class¬ ification for Building Ener¬ gy Codes and Standards: Part 2 – Zone Definitions, Maps, and Comparisons,” ASHRAE Winter Meeting, 2003. E.F.P. Burnett, “Development of Design Strategies for Rainscreen and Sheathing Membrane Performance in Wood Frame Walls,” ASH¬ RAE 1091-TRP, Pennsylva¬ nia State University, Oak Ridge National Laboratory, and the University of Wa¬ terloo joint research project 2004. Canadian Commission on Building and Fire Codes, National Building Code of Canada 2005 (NBC), Na¬ tional Research Council of Canada, October 2005. S.J. Emmerich, T. McDowell, and W. Anis, “Investigation of the Impact of Com¬ mercial Building Envelope Airtightness on HVAC En¬ ergy Use,” National Insti¬ tute of Standards and Technology Internal Report 7238, U.S. Department of Energy, Office of Building Technologies, June 2005. S. Gatland II, “Comparison of Water Vapor Permeance Data of Common Interior Building Materials in North American Wall Systems,” 10th Canadian Conference on Building Science and Technology, Ottowa, May 2005. S. Gatland II, A.K. Karagiozis, C. Murray, and I. Ueno, “The Hygrothermal Perfor¬ mance of Wood-Framed Wall Systems Using a Relative Humidity Depen¬ dent Vapor Retarder in the Pacific Northwest,” Ther¬ mal Performance of the Ex¬ terior Envelopes of Build¬ ings X, Proceedings of the DOE/ORNL/ASHRAE/BET EC International Confer¬ ence, Clearwater Beach, FL, December 3-6, 2007. R. Hendron, S. Farrar-Nagy, R. Anderson, P. Reeves, and E. Hancock, “Thermal Performance of Unvented Attics in Hot-Dry Climates: Results from Building America,” International Solar Energy Conference, Hawaii Island, Hawaii, March 15-18, 2003. H. Hens, T. Ojanen, H.M. Kunzel, G. Dow, C. Rode, and C.E. Hagentoft, “Heat, Air and Moisture Transfer in Insulated Envelope Parts,” Final Report, Vol¬ ume 1, International En¬ ergy Agency Annex 24, Laboratorium Bouwfysica, K. U. -Leuven, Belgium, 1996. International Code Council (ICC), Inc., 2003 & 2006 International Energy Con¬ servation Code, “Chapter 8 – Design by Acceptable Practice for Commercial Proceedings of the RCI 24th International Convention Gatland – 53 Buildings,” 2003, 2006. International Code Council (ICC), Inc., 2003 & 2006 International Residential Code for One- and Two- Family Dwellings, “Chapter 3 – Building Planning,” 2003, 2006. A.N. Karagiozis and A.O. Desjarlais, “The Hygrothermal Performance of Vapor Retarders in Wall Systems for U.S. Climatic Condi¬ tions,” Oak Ridge National Laboratory Report pre¬ pared for the North Amer¬ ican Insulation Manu¬ facturers Association (NAIMA), February 2005. M.K. Kumaran, “Chapter 3 – Hygrothermal Properties of Building Materials,” ASTM MNL40 – Moisture Analysis and Condensation Control in Building Envelopes, H. R. Trechsel, ed., American Society for Testing and Materials, West Consho¬ hocken, PA, 2001, pp. 29- 65. J.W. Lstiburek, “Moisture Control for Buildings,” ASHRAE Journal, vol. 44, no. 2, p. 36-41, February 2002. J.W. Lstiburek, “Understand¬ ing Vapor Barriers,” ASH¬ RAE Journal, August 2004. J.W. Lstiburek, “Chapter 4 – Understanding Attic Venti¬ lation,” Building Science Consulting, October 2006. D.S. Parker, “Literature Re¬ view of the Impact and Need for Attic Ventilation in Florida Homes,” Florida Solar Energy Center – Re¬ vised Draft Report, FSECCR- 1496-05, submitted to the Florida Department of Community Affairs, May 2005. S. Quarles and A. TenWolde, “Attic and Crawlspace Ven¬ tilation: Implications for Homes Located in the Urban-Wildland Interface,” Proceedings from the Wood¬ frame Housing Durability and Disaster Issues, Las Vegas, NV, October 2004. J. Straube and E.F.P. Burnett, “Chapter 5 – Overview of Hygrothermal Analysis Methods (HAM),” ASTM MNL40 – Moisture Analysis and Condensation Control in Building Envelopes, H. R. Trechsel, ed., American So¬ ciety for Testing and Mater¬ ials, West Conshohocken, PA, 2001, pp. 81-89. A. TenWolde and W.B. Rose, “Issues Related to Venting of Attics and Cathedral Ceilings,” ASHRAE trans¬ actions, June 1999. R. Tichy and C. Murray, “Hy¬ grothermal Performance Research Program Develop¬ ing Innovative Wall Sys¬ tems that Improve Hygro¬ thermal Performance of Residential Buildings,” WSU/ORNL/DOE/Industry Cooperative Research Project, October 2003. H.R. Trechsel, ed., “Moisture Analysis and Condensation Control in Building Enve¬ lopes,” ASTM MNL 40, American Society for Test¬ ing and Materials, West Conshohocken, PA, 2001. WUFI® Pro 3.3, A PC Program for Analyzing the 1-Dimen¬ sional Heat and Moisture Transport in Building Com¬ ponents, Fraunhofer Insti¬ tute, Stuttgart – Holzkir¬ chen, Germany, 2003. Gatland – 54 Proceedings of the RCI 24th International Convention
