Managing Condensation and Thermal Performance with Continuous Insulation

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1 Managing Condensation and Thermal Performance with Continuous Insulation Presented by Brian Shores, Don Simon Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board Huber Engineered Woods LLC. All rights reserved. Page 1

2 The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider #G516. Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. Page 2

3 COURSE DESCRIPTION Building codes and green building standards continue to raise the bar on energy efficiency and building high performance. In woodframe buildings, designing for thermal and moisture management in wall cavities, as well as air tightness, are essential to creating advanced building enclosures. This presentation will focus on the effectiveness of exterior insulation for managing heat transfer and reducing condensation in exterior walls. Step-by-step examples showing how to determine the amount of continuous insulation required to meet prescriptive code requirements depending on climate zone will also be provided. Page 4

4 LEARNING OBJECTIVES After completing this presentation, you will be able to: 1. Explain the concept of thermal bridging and how it impacts building energy usage in green and sustainable building design. 2. Define the commercial and residential wood frame wall insulation requirements found in the 2015 International Energy Conservation Code (IECC). 3. Explain how condensation forms in wall cavities and investigate strategies to mitigate risk of damage to construction while maintaining sustainable and healthy indoor environments. 4. Identify the practical and green building characteristics of continuous insulation as part of the exterior wall sheathing compared with other alternatives. Page 5

5 AGENDA Section I Insulation Basics A. Heat Transfer B. Thermal Bridging C. Continuous Insulation Principles Section II Continuous Insulation in Codes and Standards A IECC B. Vapor Retarders and Moisture Management Section III How Much Continuous Insulation to Use? A. Illustrative Examples B. Types of CI Page 6

6 Section I Insulation Basics U-Factor The rate of heat transfer through a material The resulting number is generally a decimal (e.g. 0.5) Smaller numbers indicate small amounts of heat transfer (think insulation) Higher numbers indicate more heat transfer (think conductive metal). Page 7

7 Section I Insulation Basics (U x A) x dt = Heat Flow U = the tested U-Factor for one square foot of material A = the area in square feet installed in a construction assembly dt = the design or actual temperature difference between indoors and outdoors Page 8

8 Section I Insulation Basics R value= 1/U Same tested measurement of materials, just expressed as inverse value R-value indicates resistance to heat flow R-values can be added mathematically U-factors can not. Page 9

9 Section I Insulation Basics Which has a higher R-value 5-1/2 inches of wood framing or 5-1/2 inches of typical cavity insulation? 2x6 Framing = R /2 Batt Insulation = R-20 Page 10

10 Section I Insulation Basics Framing can account for 20 25% of a typical wall assembly reducing the overall, effective R- value considerably. The framing is a thermal bridge between interior and exterior. Page 11

11 Section I Insulation Basics Complete Wall Assembly Example #1 2x6 Framing 2x6 wood stud framing at 24 inches on center with R-20 insulation between the studs Framing reduces effective R-Value dramatically Page 12

12 Section I Insulation Basics Continuous Insulation (CI) is Insulation that is continuous across all structural members without thermal bridges other than fasteners and service openings Page 13

13 Section I Insulation Basics Typical Installation R-13 Cavity Insulation Interior Gypsum Board Exterior Sheathing 2x4 Framing R-5 Continuous Insulation Page 14

14 Section I Insulation Basics Complete Wall Assembly Example #2 2x4 at 16 oc with CI Virtually the same effective R-value as 2x6 wall Page 15

15 AGENDA Section II Continuous Insulation in Codes and Standards A IRC and IBC B IECC C. Vapor Retarders and Moisture Management Page 16

16 Section II - Continuous Insulation in Codes and Standards 2015 International Energy Code Six chapters for Residential Six similar chapters for Commercial Multifamily 3 stories or less follows residential portion of IECC Multifamily over 3 stories follows commercial portion of IECC. Page 17

17 Section II - Continuous Insulation in Codes and Standards ASHRAE 90.1 Applies to all commercial buildings Recognized by IECC as equivalent path to compliance. Some differences in requirements compared to IECC Design teams must choose as a basis for non-residential buildings. Page 18

18 Section II - Continuous Insulation in Codes and Standards 7 Page 19

19 Section II - Continuous Insulation in Codes and Standards Prescriptive vs. Performance Showing IECC compliance with the Prescriptive Path relies on showing specific prescriptive requirements for each component of the building envelope are part of the design and construction of the building. Page 20

20 Section II - Continuous Insulation in Codes and Standards Prescriptive R-Values Based first on climate zones. Wood framed walls are shown as cavity insulation plus continuous insulation minimums. R-values are based purely on insulation not total assembly. Page 21

21 B. IECC Prescriptive U-Factors Also based on climate zones. U-Factor is based on total construction assembly, not just insulation as in R-value tables. Page 22

22 Section II - Continuous Insulation in Codes and Standards Prescriptive vs. Performance Performance Path relies on computer software to show overall compliance. Some trade-offs are allowed Non-compliant prescriptive portions can be offset by over complying portions. Page 23

23 Section II - Continuous Insulation in Codes and Standards Page 24

24 Section II - Continuous Insulation in Codes and Standards Water Vapor Permeance The rate of water vapor that diffuses through a material Reported using the unit: Perms ASTM E96 Standard Test Method for Water Vapor Transmission of Materials Test Sample Humidity Controlled Chamber 50% RH 0% RH 100% RH Procedure A (Dry Cup) Procedure B (Wet Cup) Page 25

25 Section II - Continuous Insulation in Codes and Standards Vapor Retarder Classification Class I -very low perm rating of less than or equal to 0.1 -sheet polyethylene, non-perforated aluminum foil, some plastic foam insulation Class II - moderate perm rating greater than 0.1 but less than or equal to 1.0 -kraft paper faced fiberglass batts or certain vapor retarder tested paints Class III - higher perm rating of greater than 1.0 but less than or equal to most latex or enamel paint. Page 26

26 Section II - Continuous Insulation in Codes and Standards Vapor Retarder Requirements Climate Zone 2015 IRC R Not Required Marine 4 Class I or II 5 Class I or II 6 Class I or II 7 Class I or II 8 Class I or II Page 27

27 Section II - Continuous Insulation in Codes and Standards Climate Zone 2015 IRC - R x4 2x6 1 N/A N/A 2 N/A N/A 3 & 4 N/A N/A Marine 4 R > 2.5 R > R > 5 R > R > 7.5 R > & 8 R > 10 R > 15 Exception: Class III Vapor Retarders are permitted when proper amounts of continuous insulation is used Page 28

28 Section II - Continuous Insulation in Codes and Standards CI requirements in the IECC differ from those found in the IRC IECC = Energy Usage IRC = Condensation Control Climate Zone 2015 IRC - R x4 2x6 1 N/A N/A 2 N/A N/A 3 & 4 N/A N/A Marine 4 R > 2.5 R > R > 5 R > R > 7.5 R > & 8 R > 10 R > IECC R402.1 N/A N/A 20 or or or or or Page 29

29 Section II - Continuous Insulation in Codes and Standards Condensation In Walls Cold, Dry (Outside) Warm, Humid (Inside) Page 30

30 Section II - Continuous Insulation in Codes and Standards How to Determine Sheathing Temperature Sheathing Temp = Indoor temp [(Indoor temp Outdoor temp) X (Cavity R/Total R)] Page 31

31 Condensation Example #1 Burlington, VT Climate Zone 6 -Interior Temp = 70 F -Interior RH = 30% -Dew Point = 37 F -online calculator -Outdoor Temp = 21 F -avg of Dec, Jan, and Feb Temperature Gradient Dew Point Sheathing temperature is below the dew point Temperature Page 32

32 Condensation Example #2, Add R5 Continuous Insulation Burlington, VT Climate Zone 6 -Interior Temp = 70 F -Interior RH = 30% -Dew Point = 37 F -online calculator -Outdoor Temp = 21 F -avg of Dec, Jan, and Feb Temperature Gradient Dew Point Sheathing temperature is below the dew point Temperature Page 33

33 Condensation Example #3, Add R11.25 Continuous Insulation Burlington, VT Climate Zone 6 -Interior Temp = 70 F -Interior RH = 30% -Dew Point = 37 F -online calculator -Outdoor Temp = 21 F -avg of Dec, Jan, and Feb Temperature Gradient Dew Point Sheathing temperature is above the dew point Temperature Page 34

34 AGENDA Section III How Much Continuous Insulation to Use? Page 35

35 Section III How Much Continuous Insulation to Use? Start with Basics 1. Confirm project as either residential or commercial under the IECC, not just under the IBC and IRC 2. Confirm Climate Zone from IECC 3. Agree on whether the IECC or ASHRAE 90.1 will be basis of compliance 4. Choose between prescriptive requirements or computerized performance analysis Page 36

36 Section III How Much Continuous Insulation to Use? Burlington, VT 3 Story Multifamily First determine which Codes are relevant Multifamily 3 stories or less follows residential portion of IECC and IRC Page 37

37 Section III How Much Continuous Insulation to Use? Burlington, VT 3 Story Multifamily Second determine Climate Zone Burlington is located in Climate Zone 6 Page 38

38 Section III How Much Continuous Insulation to Use? Burlington, VT 3 Story Multifamily Next determine prescriptive wall insulation requirements from IECC For Climate Zone 6 there are 2 options Page 39

39 Section III How Much Continuous Insulation to Use? Burlington, VT 3 Story Multifamily Then determine vapor retarder requirements from IRC A Class I or II is required in climate Zone 6 unless Page 40

40 Section III How Much Continuous Insulation to Use? Burlington, VT 3 Story Multifamily In this example we have 4 options A Class I or II is still required with this option This option doesn t meet IECC requirements Climate Zone 2015 IRC - R x4 2x6 6 R > 7.5 R > IECC R x4 2x Encourage drying by using the most vapor permeable material allowed, i.e. avoid using Class I where Class II is allowed, and avoid using Class II where Class III is allowed. Avoid low permeance vapor retarders on both sides of assemblies in order to facilitate assembly drying in at least one direction. Most continuous insulation is low permeance Page 41

41 Section III How Much Continuous Insulation to Use? Most Common Types of CI Polyisocyanurate Expanded Polystyrene (EPS) Continuous insulation differs in: R-value Moisture Resistance Extruded Polystyrene (XPS) Mechanical Properties (rigidity, compressive, etc.) Environmental Impact (blowing agents, ODP, GWP) Fire Resistance Mineral Wool Page 42

42 Section III How Much Continuous Insulation to Use? Other Considerations with CI Wall Bracing WRB Location Window Installation Siding and Trim Attachment Durability Page 43

43 A New Approach Combination Sheathing Single product with both structural sheathing panel and an integrated layer of continuous insulation. Eliminates a labor step by installing both continuous insulation and a structural, nailable, sheathing all at once. Available in R-3 to R-12 using Polyiso insulation Page 44

44 A New Approach Combination Sheathing Best option is to rely on a product that has been tested. One manufacturer has obtained third-party documentation through the International Code Council s Evaluation Services to be used as an acceptable structural panel. See Evaluation Service Report ESR-3373 Page 45

45 YOUR QUESTIONS? Page 46

46 This Concludes the American Institute of Architects Continuing Education System Course Brian Shores/Don Simon For more information contact: ZIPSystem.com AdvanTechPerforms.com 47 Page 47