PARAPETS + PROJECTIONS

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1 Key Junctures DESIGN INVESTIGATE REHABILITATE Key Junctures and Interfaces for Air Barriers Presented by: Vince Cammalleri, AIA Senior Principal Simpson Gumpertz & Heger Inc. CONTINUITY of air barrier installations fail most frequently at the following transitions: Parapets and projections. Roof/wall intersection. + Window/wall interface. 12 April Parapets PARAPETS + PROJECTIONS Other Common Building Projections Wall Fins Where to put C.I.? SASM Insulation Vapor Permeable WRB ROOF/WALL INTERFACE NREL, Golden, CO Plan Section Sheathing very cold even if c.i. provided. 5 1

2 Qualitative Testing Infrared Thermography Preventing Condensation Within Walls and Roofs 2

3 Preventing Condensation Within Walls and Roofs 3

4 Qualitative Testing Infrared Thermography Perforated Metal Deck Standing Seam Metal Roof Batt Insulation Rigid Insulation Gypsum Wallboard Bulkhead EAVE DETAIL Structural Steel Metal Soffit Construction Geometries 22 Construction Geometries Preventing Condensation Within Walls and Roofs 23 4

5 AIR BARRIER CONTINUITY VAPOR RETARDER CONTINUITY THERMAL BARRIER CONTINUITY 5

6 Art Museum in a Cold Climate Overall Survey Primary issue: Roof-to-Wall Polyethylene sheet used as roof air barrier not ideal, but relatively effective in this application No transition from wall to roof barrier Repairs Simple but complex WINDOW/WALL INTERFACE 6

7 The Four Barriers Key Design Considerations BARRIER 1: Waterproofing BARRIER 2: Insulation BARRIER 3: Vapor Retarder BARRIER 4: Air Barrier Rainwater/Groundwater Control Condensation Control & Energy Consumption Wall system design performance capabilities, four barrier planes. Window system design configuration, accessories and limitations. Interior operating conditions and air pressures humidified buildings. Appropriateness/relevance of laboratory and field tests mock-up design and testing. Continuity of Thermal Barrier Short-circuits at thermal break material. Effect of window accessories starter sills. Alignment of thermal barrier plane of window system with wall insulation. Window Sill - Baseboard Sill Flashing Waterproofing The most important single element in waterproofing performance: Provide slope to drain horizontal portions of flashing. Do not penetrate horizontal leg of flashing. Turn flashing up at interior edges and at ends to prevent over-topping or bypassing. Provide weatherproofed expansion/contraction joints at laps in finishing recommend adhered rubber sheet with metal cover plate. Work out sequencing and coordination of multiple trades involved in flashing and veneer installation shop drawings are generally not comprehensive in scope. 7

8 Continuity of Air Barrier/Vapor Retarder (AVB) and Waterproofing Air barrier/wp plane of window system. Configuration of extrusion/frame at sill, jamb, and head. Material bonding, forming, compatibility. Transition seal sealant, foam, membrane, compression (mechanical), Engineered Transition Assembly Perimeter Seals Sealant to Side of Frame AVB Seal/backup WP AVB/Waterproofing WP first line of defense Relies on sealant joint bond to polyethylene; surface preparation. Difficult transition to sill flashing. Potential air flow through side of frame. Interior frame accessible/visible. Perimeter Seals Spray Foam to Side of Frame DESIGN INVESTIGATE AVB Seal/backup WP AVB/Waterproofing REHABILITATE WP first line of defense Relies on foam bond to polyethylene, surface preparation, shrinkage. Difficult transition to sill flashing. Air flow through side of frame can be mitigated. Continuity of thermal barrier facilitated. 8

9 Perimeter Seals Membrane to Side of Frame Perimeter Seals Membrane to Glazing Pocket AVB/Waterproofing adhered to side AVB/Waterproofing adhered to pocket. WP first line of defense Works better with flush, smooth frame edges; good for ETA products. Difficult transition to sill flashing. Sequencing of cladding installation. WP first line of defense Consistent through full perimeter; mechanically supported. Requires screw spline modification at verticals. Limited depth of WP protection. Sequencing of cladding installation. REHABILITATE INVESTIGATE DESIGN REHABILITATE INVESTIGATE REHABILITATE INVESTIGATE DESIGN DESIGN 9

10 Perimeter Seals Membrane to Nailing Flange Clad Wood Windows Nailing Flanges Nailing Flange AVB/Waterproofing adhered to nailing flange Sealing the air barrier to the nailing flange might not provide an air-tight envelope if the cladding material is not fused or welded continuously at the corners. WP first line of defense Sealing the air barrier to the nailing flange at the window sill will impede drainage. Performance relies on window/flange assembly. Needs special attention at sill flashing. REHABILITATE INVESTIGATE DESIGN 10

11 Flanged window Provide notches or weeps in sill flange Self-adhered membrane flashing Sealant Metal angle Weather resistant barrier Cladding (stucco shown) Typical Window Sill at Flanged Window 11

12 Perimeter Seals Membrane to Back of Frame AVB Seal/backup WP AVB/Waterproofing Perimeter Seals Membrane to Back of Frame Alternate (Two-Piece) AVB Seal/backup WP AVB/Waterproofing WP first line of defense Works reliably with mechanical attachment. Provides best WP protection at sill, jamb, and head. Easy transition to sill flashing. Air flow through side of frame. Interior frame obstructed; needs coordination w/ finishes. WP first line of defense Provides WP protection at sill, jamb and head. Difficult transition to sill flashing. Air flow through side of frame. Interior frame obstructed; needs coordination w/ finishes. Continuous Attachment to Interior of Frame: Sill Condition AVB Seals (sealant or butyl tape) Metal Flashing AVB/backup WP Continuous angle at sill, jamb and head. Sealant joint w/ weeps FRAME FASTENED FROM THE INTERIOR THROUGH THE ANGLE; FASTENERS TO NOT PENETRATE FLASHING ELEMENTS. 12

13 REHABILITATE INVESTIGATE DESIGN Inc Simpson Gumpertz & Heger 13

14 Windows in Precast The Right Curtain Wall in the Wrong Place Precast concrete panels are the acting air barrier in the wall system. Setting the window on the precast creates a thermal bridge which can lead to condensation. 49 ºF T ext = 0 F T 51 ºF int = 70 F 51 ºF The Right Curtain Wall in the Wrong Place 40 ºF T ext = 0 F T 41 ºF int = 70 F 42 ºF 14

15 Window Precast Interface

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17 97 98 Paths of Air Leakage through Sides of Frame Improperly sealed corners, including thermal break material. Notched corners in mitered aluminum frames. Notched openings or other perforations in the window frames made to support insect screens, storm window sash, or accessories. Hardware penetrations, such as pivoting window mechanisms, sash balance (jamb) clips, hinge arms, etc. Penetrations at window anchors. Improperly capped or sealed ends at mullions or field-mulled units. 17

18 Laboratory Testing for Air Leakage Two approaches, depending on window type and location of air barrier seals at window perimeter: ASTM E-283 Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen ASTM E Standard Test Method for Determining Air Flow Through the Face and Sides of Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen Perimeter Seal Options Laboratory Set-up E283 3: Specimen Air Leakage Q s = Specimen Air Leakage Face Side/Caulk Stop Air Barrier Tie-in Nailing/AB Flange Glazing Pocket/CW 18

19 Perimeter Seals AB/Waterproofing Sealed to Interior of Window Frame 19

20 E2319 Leakage through Face E2319 Leakage through Sides Q s(f) = Air Leakage through Face of Specimen Q s(s) = Air Leakage through Sides of Specimen Special Cases Air Flow in Humidified Buildings In humidified, pressurized buildings that contain multiple-glazed window units (usually with integrated blinds), interior air that leaks through the sides of the frame into the interstitial space can condense within the window. 20

21 Location of air seal Pressurized Interior What Passing the Test Really Means That the system at that point in time can meet a specific established set of design parameters. It is not an indicator of future performance. Tests are tools designed to verify that a design concept or idea can work under a specific set of controlled conditions. Tests are used to verify or validate the design concept. Tests can be misleading if used to replace the analytical part of the design process. With new reporting requirement for E283 and modified testing procedure for E2319, manufacturers may begin to address perimeter seal conditions by defining the intended air barrier plane. Ideally, extrusions will begin to include provisions for air barrier tie-ins. 21

22 Simpson Gumpertz & Heger Consulting Engineers Building Engineering Infrastructure and Special Structures Construction Engineering INVESTIGATE REHABILITATE DESIGN Thank You Vince Cammalleri, AIA