owens corning

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Air Sealing & Insulating Residential BuildingsGHBA Custom Builder Council

20 September 2011

Dave Wolf, Ph.D.

Owens Corning, Science & Technology

Outline | Three Key Areas of Focus

• Air Sealing

– Why & how houses leak

– Importance

– Measuring air leakage

Sealant choices

• Insulating

– Material choices

– Proper installation

– How infraredthermography can help

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– Sealant choices

– Ventilation

2Confidential Information

thermography can help

• Bonus Room Comfort

– Why it is such a challenge

– How it can be addressed with effective air sealing & insulating

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AIR SEALING

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How leaky is a typical house?

Air Sealing

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Median air leakage of existing homes is 0.5 NACH.Residential Energy, Krigger & Dorsi.

Leaky enough to exchange all of its volume with the outside every two hours.

Where do houses leak? | Attic

Light fixtures Chimneys Wall-ceiling intersections

Air Sealing

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Light fixtures Chimneys Wall ceiling intersections

Hatches Vents Bath fans Soffits/Chases

Drawings from “Attic Bypasses,” Minnesota Department of Commerce Energy Information Center.

Where do houses leak? | WallsAir Sealing

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Drawing from “The Facts About Insulation And Air Infiltration,” NAIMA Pub. No. BI 480.

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Why do houses leak air?

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2

Air Sealing

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Drawing from Green Building Advisor website.

What are the benefits of reduced air leakage?Experience dramatic savings on home heating and coolingSee immediate savings of up to one‐third on heating and cooling.

Enjoy a more comfortable homeMore consistent room‐to‐room comfort with fewer drafts. Feel warmer in the winter, cooler in the summer.

Help prevent moisture from entering wallsReduce conditions that can lead to the growth of mold.

Air Sealing

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Diminish outside noise penetrationUp to 40% less outside noise from traffic and neighbors, as compared to traditional spray foam systems.

Defend against insects and pestsBlock gaps and holes to create a first line of defense against the critters and pests that bug your family.

Improved indoor air qualityHelp seal out allergens and pollutants to create a healthier indoor environment with the inclusion of a mechanical air exchanger.

How do you measure air leakage?

• The “Blower Door” test.

– Pressurizes/depressurizes the house to measure leakage.

– Blower is quickly inserted into the door of the house

Air Sealing

into the door of the house.

– The amount of air leakage is commonly normalized to the house volume – air changes per hour at 50 Pascals of pressure (ACH50).

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Sealant ChoicesAir Sealing

Pros Cons

Caulk

• Low cost • Poor flexibility (without silicone) & compressibility

• Requires clean surface•No hard‐to‐reach joints

Can Foam

• Low cost•Good expansion

• Poor flexibility & compressibility

• Requires clean surface


Spray Applied Flexible Foam

• Excellent flexibility & compressibility

• Self‐cleaning spray• Seals hard‐to‐reach joints

•Moderate cost

Full Cavity Spray Foam

• Excellent expansion• Seals hard‐to‐reach joints• Insulates

•High cost• Does not address all joints

Ventilation

• Old (and accurate) adage …build tight, ventilate right.

– Infiltration (uncontrolled)

– Ventilation (controlled)

• Types of ventilation

Air Sealing

Types of ventilation

– Supply

– Exhaust (not recommended for Houston climate)

– Balanced with heat recovery

• The builder should consult with the HVACcontractor on the selection and installation.


INSULATING

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Material & Application ChoicesInsulating

• Fiber Glass

• Cellulose

• Spray Polyurethane Foam

• Foam Board


Fiber Glass

• Advantages

– Inexpensive

– Easy to install

– Excellent fire & moisture resistance

Insulating

• Disadvantages– Batts must be custom fit for

irregularly shaped cavities and obstructions

– Does not air seal


Cellulose

• Advantages

– Inexpensive

– Easy to install

– Provides some air resistance when tightly packed

Insulating

• Disadvantages– Absorbs water

– Can settle in wall cavities

– Requires chemical treatment to avoid fire hazard

– Does not air seal


Spray Polyurethane Foam (SPF)

• Advantages

– Easily handles irregularly shaped cavities and obstructions

– Air seals the cavities

• Disadvantages

Insulating

g– Expensive

– Requires building evacuationduring installation and for24 hours thereafter

– Requires highly trained installers


Foam Board

• Advantages

– Continuous thermal break(not interrupted by the framing)

– Can function as the water barrier, if properly detailed

Insulating

• Disadvantages

– May require window/door jamb extensions, depending on the thickness.

– Requires some form of shear bracing when applied instead of OSB or plywood.

17Confidential Information 18Confidential Information

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More Information

• 12‐page pictorial document that includes quality checklists, critical details and more.

Insulating

www.owenscorning.com


How infrared thermography can help …Insulating


BONUS ROOM COMFORT

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What affects comfort?Bonus Room Comfort

Relative HumidityMoist air that infiltrates in the summer makes a person feel warmer. Moist air that exfiltrates in the winter makes a person feel cooler.

Air Temperature


Source: Krigger, J. & Dorsi, C., Residential Energy, Cost Savings and Comfort for Existing Buildings, 4th ed., Saturn Resource Management, 2004.

Air FlowAir infiltration gives the sensation of draftiness.

RadiantTemperatureAir infiltration and/or inadequate insulation effects the wall surface temperature, which, through radiation, affects thermal comfort.

The Silver Bullet …

• Bad news … There isn’t one.

• A bonus room is the most thermally challenging place in the house

Bonus Room Comfort

– Five‐sided exterior enclosure

• The details of construction are really important.


• Thermal barrier• Air barrier

• Windows• HVAC• Lighting

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Thermal Barrier

• Two important requirements for the proper installation of insulation

1. Minimize/eliminate air leakage through the insulation by ensuring a 6‐sided cavity• Think of a sweater … very warm with no wind blowing; not so

Bonus Room Comfort

Think of a sweater … very warm with no wind blowing; not so warm with the wind blowing. The 6‐sided cavity is the “windbreaker” over the “sweater”.

2. Ensure contact with the surface that you want to insulate• Think of a blanket … very warm when in contact with the body; not so warm when separated


Thermal Barrier | Walls

• Insufficient sheathing on the knee wall

Bonus Room Comfort

Air leakage paths


Air leakage paths


• Open stud cavities

Bonus Room Comfort

atticspace


Air leakage paths


• Double walls

Bonus Room Comfort


Double-depth cavity; unbacked insulation

Air leakage

path


• Unbacked walls

Bonus Room Comfort


His & Herscloset

All arrows show air leakage paths and areas of

unbacked insulation.

Thermal Barrier | Floor

• Contact with the sub‐floor is essential

Bonus Room Comfort

Correct Wrong


Source: Krigger, J. & Dorsi, C., Residential Energy, Cost Savings and Comfort for Existing Buildings, 4th ed., Saturn Resource Management, 2004.

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Thermal Barrier | Floor

• Piping creates a challenge for achieving contact with the sub‐floor.

Bonus Room Comfort

• Could the plumbing contractor apply a rigid insulation between the pipes and sub‐floor (e.g., foam)?


Thermal Barrier | Ceiling

• Continuous and alignedair baffles in cathedral ceilings keeps the warm/cold air from seeping into the

Bonus Room Comfort

p ginsulation.


Air leakage paths

Air Barrier | Walls

• Same examples as with the thermal barrier …

Bonus Room Comfort

Double-depth cavity; unbacked insulation

Air leakage

path


All arrows show air leakage paths and areas of

unbacked insulation.

Air leakage paths

Air Barrier | FloorBonus Room Comfort

Garage House

Bonus Room

All drywallpenetrations

must be sealed.

Floor temperature is affected.


All drywallterminations

must be sealed.

Air Barrier | Ceiling

• Seal around recessed lights.

Bonus Room Comfort


Source: Retrofit Techniques & Technologies: Air Sealing – A Guide for Contractors to Share with Homeowners, U.S. Department of Energy, 2010


• Seal around exhaust fans.

Bonus Room Comfort


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• Seal around duct boots.

Bonus Room Comfort


Without a seal, the air from the duct boot entrains unconditioned attic air at the drywall interface.


• Seal the top plates.

Bonus Room Comfort


Sealant

Windows

• Minimize their use in bonus rooms

– Windows are a weak link in the wall’s thermal barrier.

• Consider higher performance windows on south‐facing and west‐facing walls of bonus rooms

Bonus Room Comfort

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– Low‐e coatings for a cooling climate, like Houston.


HVAC

• Things to consider

– Duct size• Is it large enough for the length of run and higher thermal load associated with a bonus room?

– Duct kinks• The attic space above a bonus room is often smaller than the rest

Bonus Room Comfort

The attic space above a bonus room is often smaller than the rest of the house, making duct kinks more likely.

– Duct sealing• Prevents loss of conditioned air to the attic (supply) and gain of unconditioned air from the attic (return).

– Returns• Bathroom & closet doors are often closed for privacy, which makes the presence of a return duct more important.


Lighting

• Bathrooms typically have the largest concentration of artificial lighting of any room in the house

• Incandescent lighting will worsen a

Bonus Room Comfort

Incandescent lighting will worsen a comfort problem in summer months

• Compact fluorescent lights (CFLs) significantly reduce this thermal load


MORE INFORMATION

BooksResidential Energy, Krigger & Dorsi

Websites• Written

• www.greenbuildingadvisor.com• www.buildingscience.com

QUESTIONS?

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g• Video

• www.homeenergypros.lbl.gov• www.bestofbuildingscience.com

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