All About Air Barriers – The Basics

ABAA XX-XX Rev 0 issued March 2013

ABAA Process for Approval – Explained Air Barrier Association of America (ABAA) is a Registered Provider with the American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request. This program is registered with the 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.

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Learning Objectives • • • •

Explain “air barrier” terminology Understanding building science principles Explain air barrier basics List air barrier codes and standards requirements

Definitions • air barrier material building material with an air permeance not greater than 0.02 L/s·m² at 75 Pa that is designed and constructed to provide the primary resistance to airflow through an air barrier assembly.

• Vapor Permeable (vapor Barrier) The property of having a moisture vapor permeance rating of 10 perms (5.7x 10-10 kg/Pa◦s◦m2) - IBC [5 perms (2.9x 10-10 kg/Pa◦s◦m2) – IRC] or greater, when tested in accordance with the desiccant method using Procedure A of ASTM E96.

Definitions • air barrier accessory materials designated to maintain air tightness between air barrier materials, air barrier assemblies and air barrier components, to fasten them to the structure of the building, or both.

• air barrier assembly combination of air barrier materials and air barrier accessories that are designated and designed within the environmental separator to act as a continuous barrier to the movement of air with an air leakage not greater than 0.20 L/s·m² at 75 Pa.

Definitions • air barrier system combination of air barrier assemblies and air barrier components, connected by air barrier accessories, that are designed to provide a continuous barrier to the movement of air through an environmental separator .

• air barrier components pre-manufactured elements such as windows, doors and service elements.

Definitions • Water vapor permeability time rate of water vapor transmission through a material at a specific thickness. This would be most applicable to materials that can vary in thickness such as boardstock, fluid-applied, spray polyurethane foam (SPF) air barriers.

• Water vapor permeance the time rate of water vapor transmission through a material of a unit thickness. Permeance is a performance evaluation and not a property of a material. This would be most applicable to materials which don’t vary in thickness such as self-adhered sheet materials and mechanically fastened building wraps.

Six Air Barrier Materials • Mechanically Fastened - Membranes • Mechanically Fastened - Insulating Boardstock • Mechanically Fastened - Non-insulating Boardstock • Self-adhered Membrane • Fluid-applied Foaming • Fluid-applied Non-foaming

Building Science The“ definition of building science is the physics of: • Heat flow • Air flow • Moisture flow – in a building

Building Science The building is a system. A building is made up of many components that work together: • Building enclosure • People • Mechanical system • Ambient conditions

Building Science The building enclosure is: • The building components that separate one environment from another environment. • Includes inside environment from outside environment • Can also include one environment from another environment within a building

Building Science People effect buildings by: • Daily activities (bathing, breathing, cooking, etc.) • How they treat the building envelope (opening window, etc.) • How they operate the mechanical system (positive or negative pressurization)

Building Science Mechanical systems effect buildings by: • • • •

Adding / removing heat Adding / removing moisture Creating different air pressures Moves air / heat / moisture from one part of the building / building component of another

Building Science Ambient conditions effect buildings by: • Air leakage containing water vapor • Bulk water leaking into walls through:  voids in WRB  improper drainage in design/installation • Creating different air pressures • Drying potential of climate • Freeze/thaw

Building Science Effects of uncontrolled air leakage…

Building Science Heat always flows from hot to cold Heat Flow: • Requires temperature difference • Rate is dependant on temperature difference • Greater temperature difference equals greater heat flow

Building Science What are the three ways heat flow? • Conduction • Convection • Radiation

Building Science Conduction: • Heat transferring through a substance • Rate is based on temperature difference • Different materials have different flow rates What are examples of heat flow by conduction?

Building Science Convection: • Heat transferred from one surface to another surface by means of a fluid medium (ie. air, water, etc.) • Rate is based on temperature difference and type of medium What are examples of heat flow by convection?

Building Science Radiation • Heat transferring from the source to an object without heating the medium between • Rate based on strength of heat source and ability of object to absorb energy What are examples of heat flow by radiation?

Building Science Pressure differences are caused by: • Stack effect • Wind effect • Flue and ventilation effect

Building Science Stack Effect • In winter warm air rises and causes:  Exfiltration (positive pressure) at top  Infiltration (negative pressure) at bottom

• In summer the air pressures are opposite:  Exfiltration (negative pressure) at top  Infiltration (positive pressure) at bottom

Building Science STACK EFFECT

Building Science Wind Effect • Wind blows against the building and causes:     

High pressure on the windward side Low pressure on leeward side Infiltration on windward side Exfiltration on leeward side Low pressure forces can be higher than higher pressures

Building Science WIND PRESSURE + PRESSURE

- PRESSURE

Building Science Mechanical pressurization and ventilation effect: • Fans draw air through a building • Will create negative and positive pressures in a building • Causes infiltration and exfiltration through a building

Building Science MECHANICAL PRESSURIZATION

Building Science MECHANICAL PRESSURIZATION

Building Science Moisture (water): • Can exist as a solid or liquid • Moves from wet to dry • Moves to the path of least resistance

Building Science Water moisture flows four different ways: • Gravity • Capillary • Diffusion • Air transport

Building Science Gravity Use shingles, flashings, etc. to protect buildings

It has been estimated that bulk Water causes 90% of the problems in buildings.

Building Science Capillary Use a capillary break or moisture barrier to protect building

Building Science Diffusion - through a material Use a vapor barrier / vapor retarder to protect building

Building Science Air Transport Use an Air Barrier or do air sealing to protect the building

Building Science 1 METRE TRANSPORT VIA AIR LEAKAGE 1 METRE

30 LITRES 2 cm x 2 cm HOLE

TRANSPORT VIA DIFFUSION

0.5 LITRES *ASSUMES RH 40%, 2 COATS ENAMEL PAINT, OTTAWA CLIMATE

Building Science Water vapor condensing in the building envelope leads to problems such as: • Mold • Corrosion • Wood rot • Ice lensing, etc.

Building Science Relative Humidity • The amount of moisture in the air compared to the amount of moisture the air can hold at a specific temperature. This will change as temperature changes even when the absolute humidity remains exactly the same.

Building Science Dew Point • The temperature where the relative humidity reaches 100% and the water vapor changes to liquid water • Remember liquid water causes 90% of the problems in buildings

Building Science Conclusion • Need to look at buildings as a system • Air barriers are only one component, we need to look at insulation, drainage, permeability, ambient conditions, etc • You need to address mechanical systems with building air-tightness • Building enclosures are important link to building performance and energy efficiency

Introduction to Air Barriers What materials does ASHRAE 90.1 classify as air barrier materials? Plywood-minimum 3/8 in. Oriented strand board-minimum 3/8 in. Extruded polystyrene insulation board-minimum ½ in Foil-faced urethane insulation board-minimum ½ in Exterior gypsum sheathing or interior gypsum boardminimum 1/2 in. • Cement board-minimum 1/2 in. • Built up roofing membrane • Modified bituminous roof membrane

• • • • •

Introduction to Air Barriers What materials does ASHRAE 90.1 classify as air barrier materials? • Fully adhered single-ply roof membrane • A Portland cement/sand parge, stucco, or gypsum plasterminimum 1/2 in. thick • Cast-in-place and precast concrete. • Sheet metal • Closed cell 2 lb/ft3 nominal density spray polyurethane foamminimum 1 in.

Introduction to Air Barriers What materials are NOT classified as air barrier materials? • • • • • • • • •

Tempered hardboard, plain fiberboard, flakewood board Asphalt saturated felt paper (15# and 30#) Vermiculite insulation Concrete Masonry Units Expanded Polystyrene Glass fiber rigid insulation board Asphalt-impregnated fiberboard Glasswool & Cellulose Insulation Brick

Introduction to Air Barriers Air barrier materials can be: • Vapor Permeable (high perm rating) • Non-Vapor Permeable (low perm rating provides vapor barrier function) • Insulation (providing air, vapor and thermal function)

Introduction to Air Barriers Air barrier assembly key requirements • Continuity (most important / most difficult) • Strength • Durability • (Im)Permeability

Introduction to Air Barriers Air barrier system requirements • The air barrier system shall be joined in an air-tight and flexible manner allowing for the relative movement of elements due to structural and hygrothermal expansion/contraction. • Connections using transitions shall be made between:  foundation and walls  walls and windows or doors (different wall systems)  penetrations  roof and wall  change in plane  change in substrate

Introduction to Air Barriers More than just air permeance? • ABAA has developed listed of other physical properties and performance requirements for a variety of commercially available air barrier materials. This is based on four key requirements which attempt to duplicate loads on the building:  Air leakage  Continuity  Strength  Durability

Liquid Applied Membranes

Self-Adhered Sheet Air Barriers

Medium Density S.P.F.

Mechanically Fastened Building Wraps

Boardstock Air Barrier

Code Requirements • ASHRAE 90.1-2010 • ASHRAE 189.1-2011 • 2012 IECC (International Energy Conservation Code) • 2012 IRC (International Residential Code) • 2012 IgCC (International Green Construction Code) • 2012 IBC (International Building Code) • State code changes

Code Requirements ASHRAE 90.1-2010

Code Requirements ASHRAE 189.1-2011

Code Requirements 2012 IECC – Commercial Buildings

Code Requirements 2012 IECC – Residential Houses

Code Requirements 2012 IRC

Code Requirements 2012 IgCC

Code Requirements 2012 IBC • There are no air barrier requirements in the 2012 International Building Code.

Code Requirements

Code Requirements Check the ABAA website for up to date information regarding code and standards status, and further links regarding code information in various states.

LEED Requirements It is proposed that LEED v4 will reference ASHRAE 90.1-2010 as the baseline standard for energy efficiency in LEED buildings. What does this mean?

LEED buildings will require air barriers as a mandatory component.

Code Requirements States that currently require air barriers by code: • • • • • • •

Illinois Massachusetts Minnesota Georgia Rhode Island New York Maryland

Code Requirements – Whole Building Air Leakage Testing Washington State: buildings over five stories require a whole building test but the code does not require the building to pass a prescribed value. City of Seattle : All Buildings require a whole building test conducted but the code requirement does not require the building to pass a prescribed value.

Air Barrier Material??? • Peanut butter – Smooth peanut butter – Applied at 20 mils wet – Tested to ASTM E2178 – Air leakage result 0.0021 L/s·m2 – Is an air barrier material but cannot be installed as a continuous one and will not stand up to servicelife conditions.

Learning Objectives • • • •

Explain “air barrier” terminology Understanding building science principles Explain air barrier basics List US air barrier codes and standards requirements

Thank you for your time!

QUESTIONS?? This concludes The American Institute of Architects Continuing Education Systems Program 1600 Boston-Providence Hwy Walpole, MA 02081 USA www.airbarrier.org

Contact Laverne Dalgleish ABAA – Executive Director [email protected] 1-866-956-5888