WALTER SCARBOROUGH CSI CCS CCCA SCIP AIA wscarborough@hbig 214.491.7385

1. D+D Specifiers Series Air Barriers WALTER SCARBOROUGH CSI CCS CCCA SCIP AIA wscarborough@hbig.us 214.491.7385 Sponsored by

2. Webinar Intentions To provide a “big picture” overview of air barriers

3. The Debate is Over Airtightness is essential to high performance building enclosures …

4. The Debate is Over … and air barriers fulfill this critical function

5. Discovery of Air Barriers • Genesis of discovery in study of vapor barriers • Canadians have led the way in research about vapor barriers because of severe winters

6. Discovery of Air Barriers • Vapor diffusion through materials was less than infiltration of moisture-laden air through openings in the building enclosure

7. Classic Experiment • Under controlled conditions, 4’ by 8’ sheet of gypsum board • Vapor diffusion through board yields 1/3 quart of water • Moisture-laden air through 1” square hole yields 30 quarts of water

8. Air Barrier Defined “a system of building assemblies within the building enclosure - designed, installed, and integrated in such a manner as to stop the uncontrolled flow of air into and out of the building enclosure.”

9. An Additional Function Air barriers can also function as a barrier to liquid water infiltration, while allowing water vapor diffusion

10. Lack of Air Barriers Thermal imaging of air infiltration at base

11. Lack of Air Barriers Thermal imaging of air infiltration around door frame

12. Lack of Air Barriers Thermal imaging of air infiltration at base and around electrical outlet

13. Lack of Air Barriers Thermal imaging of air infiltration at window and building corner

14. Voluntary to Mandatory Air barriers have been voluntarily used and included as part of a prudent design however That is about to change

15. Rapidly Approaching Future • 2012 International Energy Conservation Code will contain requirements for air barriers • Must pass one of three levels of performance: • Material • Assembly • Building

16. Material Performance Air permeance of less than or equal to 0.004 cfm/ft2under a pressure differential of 0.3 in. w.g. when tested according to ASTM E 2178

17. Assembly Performance Average air leakage rate of less than or equal to 0.04 cfm/ft2under a pressure differential of 0.3 in. w.g. when tested according to ASTM E 2357, E 1677, or E 283

18. Building Performance Air leakage rate does not exceed 0.40 cfm/ft2 under a pressure differential of 0.3 in. w.g. when tested according to ASTM E 779

19. Causes of Air Movement • Air always flows from: • High pressurelow pressure • Warmercolder

20. Causes of Air Movement Stack pressure occurs when atmospheric pressure differences exist between the top and bottom of a building Winter Condition

21. Causes of Air Movement HVAC equipment can create pressure in the building

22. Causes of Air Movement Winds cause pressure differentials between the interior and exterior

23. Successful Building Enclosure Exterior wall surfaces should shed water

24. Successful Building Enclosure Inevitably, some uncontrolled moisture-laden air will get past the primary building cladding, then what?

25. Successful Building Enclosure There should be a barrier that does not allow liquid water to penetrate

26. Successful Building Enclosure Depending on the geographic location of the building, a barrier that controls the passage of water vapor may be required

27. Successful Building Enclosure There should be a barrier that prevents the passage of uncontrolled moisture-laden air from penetrating into the building

28. Successful Building Enclosure There should be a thermal barrier within the building enclosure that retards the movement of heat through the building enclosure

29. Successful Building Enclosure While water is essential to sustaining life, it is the primary enemy of the building enclosure

30. Types of Air Barriers • Liquid-applied • Exterior side of the wall • Different chemical formulas • Rolled on or sprayed on • Can be applied to almost any surface • Forms continuous, • seamless membrane

31. Types of Air Barriers • Sheet-applied • Exterior side of the wall • Different sheet compositions • Mechanically attached • Seams are taped • Forms continuous membrane

32. Types of Air Barriers • Sprayed foam • Interior side of the wall • Closed cell type • Seals joints, gaps, and small openings

33. Cracks and Openings There are a considerable number of opportunities for joints, cracks, gaps, and openings

34. Cracks and Openings • Examples of cracks and openings: • Joints between differing materials • Sealants with bond line failures • Joints between rough openings and windows

35. Cracks and Openings • Examples of cracks and openings: • Cracks in masonry • Joints between sheathing panels • Joints around penetrations through the building enclosure

36. Attributes of Air Barrier Must allow water vapor to pass through the material

37. Attributes of Air Barrier Must be continuous and free of holes

38. Attributes of Air Barrier • Must be durable during construction

39. Attributes of Air Barrier Must be resistant to liquid water infiltration to prevent mold

40. Attributes of Air Barrier Must be resistant to air infiltration to eliminate those cold winter drafts

41. Attributes of Air Barrier Must be resistant to ultraviolet light degradation because it may be exposed for several months

42. Attributes of Air Barrier Must be durable over the service life of the building

43. Attributes of Air Barrier Liquid-applied air barriers must have the ability to bridge cracks in concrete masonry

44. Location of Air Barriers Generally the air barrier is located on the outside face of the sheathing or concrete masonry

45. Location of Air Barriers Common Myth: “Vapor barrier on warm side in winter” Myth Clarified: Generally applies to northern climates; vapor barriers usually not required in southern climates Air barriers should be used everywhere

46. Final Word Every building, large or small, needs an AIR BARRIER

47. Most Valuable Resource

48. D+D Specifiers Series Questions WALTER SCARBOROUGH CSI CCS CCCA SCIP AIA wscarborough@hbig.us 214.491.7385 Sponsored by