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REHABILITATE INVESTIGATE

DESIGN

Key Junctures CONTINUITY of air barrier installations fail most frequently at the following transitions:

Key Junctures and Interfaces for Air Barriers

Parapets and projections. Roof/wall intersection.

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Presented by: Vince Cammalleri, AIA Senior Principal Simpson Gumpertz & Heger Inc.

Window/wall interface.

12 April 2012 www.sgh.com

Parapets

PARAPETS + PROJECTIONS

Other Common Building Projections – Wall Fins

Where to put “C.I.”?

Vapor Permeable WRB

SASM Insulation

ROOF/WALL INTERFACE Plan Section

NREL, Golden, CO

Sheathing very cold even if c.i. provided. 5

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Qualitative Testing Infrared Thermography

Preventing Condensation Within Walls and Roofs

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Preventing Condensation Within Walls and Roofs

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Qualitative Testing Perforated Metal Deck Infrared Thermography Standing Seam Metal Roof Batt Insulation Rigid Insulation

Structural Steel Gypsum Wallboard Bulkhead Metal Soffit

EAVE DETAIL

Construction Geometries

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Preventing Condensation Within Walls and Roofs

Construction Geometries

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AIR BARRIER CONTINUITY

VAPOR RETARDER CONTINUITY

THERMAL BARRIER CONTINUITY

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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

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The Four Barriers

Key Design Considerations BARRIER 1: Waterproofing

Rainwater/Groundwater Control

BARRIER 2: Insulation BARRIER 3: Vapor Retarder

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.

BARRIER 4: Air Barrier

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.

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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.

DESIGN

Perimeter Seals – Spray Foam to Side of Frame AVB Seal/backup WP

REHABILITATE INVESTIGATE

AVB/Waterproofing

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. www.sgh.com

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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

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

• Works better with flush, smooth frame edges; good for ETA products. • Difficult transition to sill flashing. • Sequencing of cladding installation.

DESIGN REHABILITATE INVESTIGATE

REHABILITATE INVESTIGATE

DESIGN

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Perimeter Seals – Membrane to Nailing Flange

Nailing Flange

Clad Wood Windows – Nailing Flanges

 Sealing the air barrier to the nailing flange

AVB/Waterproofing adhered to nailing flange

might not provide an air-tight envelope if the cladding material is not fused or welded continuously at the corners.  Sealing the air barrier to the nailing flange at the window sill will impede drainage.

WP – first line of defense

REHABILITATE INVESTIGATE

DESIGN

• Performance relies on window/flange assembly. • Needs special attention at sill flashing.

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Sealant Flanged window

Metal angle

Provide notches or weeps in sill flange Self-adhered membrane flashing Weather resistant barrier Cladding (stucco shown)

Typical Window Sill at Flanged Window

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Perimeter Seals – Membrane to Back of Frame AVB Seal/backup WP

Perimeter Seals – Membrane to Back of Frame Alternate (Two-Piece) AVB Seal/backup WP

AVB/Waterproofing

WP – first line of defense • • • • •

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.

• • • •

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) AVB/backup WP Metal Flashing

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.

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REHABILITATE INVESTIGATE

DESIGN

5/2/2012

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Windows in Precast

The Right Curtain Wall in the Wrong Place

 Precast concrete panels are the acting air barrier in the wall system.

49 ºF Text = 0°F

Tint = 70°F

51 ºF 51 ºF

 Setting the window on the precast creates a thermal bridge which can lead to condensation.

The Right Curtain Wall in the Wrong Place 40 ºF Text = 0°F

Tint = 70°F

41 ºF 42 ºF

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Window – Precast Interface

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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.

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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 E2319 - 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

Qs = Specimen Air Leakage

Face

Nailing/AB Flange

Side/Caulk Stop

Air Barrier Tie-in

Glazing Pocket/CW

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Perimeter Seals

AB/Waterproofing Sealed to Interior of Window Frame

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E2319 – Leakage through Face

Qs(f) = Air Leakage through Face of Specimen

E2319 – Leakage through Sides

Qs(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.

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Location of air seal

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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.

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Simpson Gumpertz & Heger Consulting Engineers 

Infrastructure and Special Structures



Construction Engineering

REHABILITATE INVESTIGATE

DESIGN

Building Engineering

Thank You

Vince Cammalleri, AIA [email protected] 212-271-6990

www.sgh.com

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