Builders Websource Tech Note #021801-1

FIBERGLASS INSULATION FOR THERMAL COMFORT AND NOISE REDUCTION

Selecting the right material for the job

Last Update 06.30.12

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Summary

With ever increasing costs of energy, proper home insulation is essential to ensuring long-term comfort and value. Furthermore, insulation also has significant sound proofing benefits that add peace and quiet to a personal residence or commercial structure. Based on research by the U.S. Department of Energy -- coupled with the latest information from NAIMA and leading insulation manufacturers, this Builders Websource Tech Note explores various types of insulation with special focus on fiber glass and related building systems that will ensure enduring comfort throughout a structure's life. In addition, an interactive online "R-value" calculator developed by the U.S. Department of Energy helps architects, building designers, contractors and insulation specifiers to determine recommended insulation levels for both new and existing construction based on postal zip code.

Table of Contents

• Summary
• Introduction - Why Insulate?
• What is Insulatation
• Where to Insulate
• Types of Insulation
• Comparison of Insulation Types
• How Much Insulation Is Required?
• R-Value Calculator
• Owens Corning
• Noise Abatement
• Johns Manville ComfortTherm
• Ventilation
• References
• Copyright Notice

Introduction: Why Insulate?

Insufficient insulation exaggerates temperature swings inside a structure, causing uncomfortable draftiness. Summer days feel hotter...and winters feel colder when a home has insufficient insulation. Furthermore, under-insulated homes can cost occupants hundreds -- or thousands of dollars a year in higher heating and air conditioning bills. These costs are wasted year after year and the energy is non-recoverable. Whereas spending a little more up front pays dividends every year as the incremental cost of better insulation is amortized over the lifetime of the structure.

With so much information (and mis-information) about insulation, this Builders Websource Tech Note helps to educate designers, contractors and homeowners about this important subject by providing an in-depth look at insulation choices.

Furthermore, frequently overlooked are the sound-proofing qualities that insulation offers when combined with other sound-reduction construction techniques. Therefore, sound attenuation is one of the topics that this tech note explores.

Finally, the importance of proper home ventilation is also addressed which, if left unchecked, could result in unhealthy stale air inside tightly built new homes.

What is Insulation?

Insulation refers to special materials that impede the "thermal" conductivity between surfaces. Most of us think of traditional "blown in" type insulation or the colorful yellow or pink fiber glass or mineral wool "batt" insulation found at the local building supply store.

According to the North American Insulation Manufacturer's Association (NAIMA), insulation provides two primary comfort benefits:

• THERMAL COMFORT
  Insulation resists the flow of heat. Heat is a form of energy - it always travels from hot to cold - flowing outward in winter and inward in summer. By reducing heat flow, a properly insulated home uses less energy in winter for heating and less in the summer for cooling.
  
• ACOUSTICAL COMFORT
  Insulation is also an excellent sound absorber as well as an energy saver. When installed in the walls and ceilings, it can reduce the transmission of sound. Sound transmission is noise that travels from room to room - or from home to home - or from appliances such as washers, dryers, heating and air conditioning systems, phones, radios and TV's.

Where to Insulate

TOTAL INSULATION SYSTEM Insulation must be designed as a total system, starting with the foundation, basement, crawl space, living areas and attic. Drawing courtesy US Department of Energy

1. In unfinished attic spaces, insulate between and over the floor joists to seal off living spaces below.^*
   (1A) attic access door
   
2. In finished attic rooms with or without dormer, insulate ...
   (2A) between the studs of "knee" walls;
   (2B) between the studs and rafters of exterior walls and roof;
   (2C) ceilings with cold spaces above;
   (2D) extend insulation into joist space to reduce air flows.
   
3. All exterior walls, including ...
   (3A) walls between living spaces and unheated garages, shed roofs, or storage areas;
   (3B) foundation walls above ground level; 3C foundation walls in heated basements, full wall either interior or exterior.
   
4. Floors above cold spaces, such as vented craw spaces and unheated garages. Also insulate ...
   (4A) any portion of the floor in a room that is cantilevered beyond the exterior wall below;
   (4B) slab floors built directly on the ground;^**
   (4C) as an alternative to floor insulation, foundation walls of un-vented crawl spaces;
   (4D) extend insulation into joist space to reduce air flows.
   
5. Band joists.
   
6. Replacement or storm windows and caulk and seal around all windows and doors.

^*Well-insulated attics, crawl spaces, storage areas, and other enclosed cavities should be ventilated to prevent excess moisture build-up.

^**For new construction, slab on grade insulation should be installed to the extent required by building codes, or greater.

Types of Insulation

Comparison of Insulation Types

(source: USDOE/CE-0180)

How Much Insulation Is Required?

SIX ZONES The US Department of Energy defines six national zones for optimum insulation efficiency. Drawing courtesy NAIMA

The following table adapted from the U.S. Department of Energy outlines the minimum recommended insulation values for new construction, broken into 6 nationwide "insulation" zones. Zones 1 and 2 generally cover the Rocky-Mountain, Upper Midwest and Northeast states (including Alaska), whereas Zone 3 covers the Pacific Northwest and much of the Southwest, lower-Midwest and Southern states, with Zone 4 covering the California Central Valley, Southern Texas and Florida, with Zones 5 and 6 covering the mild California coastal regions from San Francisco on south to San Diego (Hawaii is Zone 6).

R-Value Calculator
(US Only)

Owens Corning Fiber Glass Insulation

Noise Reduction Techniques

Most leading manufacturers offer special insulation targeting sound attention applications, such as Johns Manville ComfortTherm®, CertainTeed NoiseReducer®, or Owens Corning QuietZone®, for example.  While some of these batts are unfaced, others are faced or fully sealed in a special poly-wrap exterior surface that seals in the fibers, reducing airborne insulation fibers during installation.

Contractors and consumers should be aware that sound attenuation batts are generally the same product as standard insulation, repositioned to highlight the special noise reduction properties of insulation. A leading insulation manufacturer points out that there are virtually no acoustical differences between sound attenuation batts and regular batts:

"The only difference between [sound attentuation batts] and R-11 or R-13 batts is that the [sound attenuation batts] have not been tested for R-value. The vapor barrier has no effect on the sound control quality of the insulation."

Rather than focusing too much on the insulation alone, which only adds a few dB improvement in sound transmission control, Owens Corning emphasizes overall sound reduction system, comprising special stud construction, insulation, acoustical caulking, and double-layers of drywall. When used in combination, the QuietZone® system reduces perceived sound transmission by up 80%. Uses four techniques, sound to control noise in your home – it absorbs, blocks, breaks and isolates it.

To provide better breaking, Owens Corning and Trus Joist™ have jointly developed a framing system that not only offers unique construction and superior strength, but also superior acoustic performance.

Sound vibrations readily permeate conventional wood stud framing. QuietZone Acoustic Wall Framing comes with a built-in acoustically resilient metal clip. The clip attaches between two sections of engineered lumber and causes sound vibrations to be greatly reduced between the two walls before exiting.

• Wall floats to absorb sound vibrations and reduce transmission as sound enters the wall.
• Sound vibrations from walls are greatly reduced when dispersed by metal clips.
• Wall is attached to the top and bottom framing plates, securely grounding the wall and reducing sound transmission.

2x4 QuietZone Acoustic Wall Framing has limited load-bearing capabilities and should be used on interior walls only.

* 2x6 QuietZone Acoustic Wall Framing has load-bearing capabilities similar to standard 2x4 wood framing.

JM Comfort-Therm Sound Attenuation Batts

Moisture and Ventilation

However, if the home is so well sealed that it cannot breathe, then indoor air pollution can rise to unhealthy levels. Moisture from bathrooms and cooking, as well as fumes from fireplaces, furnaces and water heaters can quickly combine into an unhealthful mixture, not to mention other sources of air pollution such as the gradual outgassing of furniture, paint, carpeting and other building products. Together, these lead to poor indoor air quality, many times worse than the outdoor air quality that normally commands our focus.

As a result, when building a super-insulated home, proper attention must be given in the design of the HVAC system. It is essential to provide for a filtered fresh air intake, coupled with an air-to-air heat exchanger. This fresh air intake, when mixed with the re-circulated air inside the home, will provide an on-going supply of healthy air for the occupants.

The heat exchanger will help to minimize heat loss by pre-warming the incoming fresh air with the outgoing stale air. This process often results in condensation which must be drained to a suitable outside location away from the foundation. Never drain condensation into a sewer line directly, as this will provide an immediate path for sewer gases to penetrate the house, which is not only dangerous, but further aggravates indoor air pollution and odors.

Conclusion

References

• CertainTeed
• Johns Manville
• North American Insulation Manufacturer's Association (NAIMA)
• Owens Corning
• US Department of Energy

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