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Insulation Location: Best Locations for Building Insulation InspectAPedia®  -     Here we describe the best location to place building insulation for heating & cooling energy savings and construction cost savings Cape-style building roof & attic knee wall insulation advice Crawl space insulation placement advice, & Basement insulation advice Insulation advice for attached building spaces such as mudrooms & Insulation advice for sunspaces Insulation advice for interior walls, stairs, plumbing fixtures

This article discusses the optimum placement of building insulation. This article explains that the location of building insulation is as important as its quantity. Sketch at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Readers concerned about termite damage associated with foam, fiberglass, or other building insulation materials should see Insects & Foam Insulation and TERMITE SHIELDS vs TERMITICIDE. Readers interested in the mold resistance properties of foam insulation should see Icynene Foam Spray Insulation.

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Where to Insulate Buildings

"Where to insulate: the location of building insulation is as important as its quantity" - links to the original article in PDF form immediately below are followed by an expanded/updated online version of this article.

• Where to Insulate in Cape Cod style homes & where to Insulate in crawl spaces - PDF form, use your browser's back button to return to this page
• Where to Insulate - PDF form, part 2 addresses basement insulation, mudroom insulation, insulation for sunspaces, and insulation for "interior bumps" or discontinuities in buildings such as stairways, cabinets, kitchen soffits, or plumbing chaseways.

This article explains the best options for insulating Cape-style homes, showing the heating and energy savings that come from proper placement of the building insulation. Next the article discusses the best placement for insulation in crawl spaces.

We add cautions about mold, moisture traps, and termite damage in crawl spaces depending on how insulation is installed.

Insulation Advice for Cape Style Homes

In the Cape-style under-roof insulation and ventilation plan suggested in this article and illustrated at page top, insulation location shown as option (B) at the right side of the sketch is the preferred insulation placement for a Cape-Cod home because

1. Less total insulation is required
2. The installation is easier
3. A larger area of heated floor space is provided.
4. The building heating costs will be less because there is less surface area through which heat may escape to cold spaces or to outdoors. Building and insulating knee walls (option (A) at page top) requires a larger insulated area so it is actually more costly to heat a building with this design.

But in any under-roof insulation scheme beware of these common Cape Cod insulation problems:

• Under-roof ventilation: be sure to provide an adequate eaves-to-ridge air path as well as actual soffit intake and ridge outlet vent openings. See ATTIC VENTILATION and see ROOF VENTILATION SPECIFICATIONS for details. If you don't think roof venting is needed, see ROOF VENTING NEEDED?
• Air leaks that defeat the building insulation scheme - see FRAMING DETAILS for BETTER INSULATION for details of how to avoid air leaks in buildings of this design

Insulation Advice for Crawl Spaces

Crawlspaces are common in homes in the southeastern U.S. as well as in some west coast cities such as Los Angeles. Crawl spaces are a breeding ground for wood decay and mold because they combine a mixture of moisture, wood, and warmth. As Mr. Bliss points out in part 1 of the article above, less insulation will be required to insulate the crawl space walls and building rim joist than to insulate under the floors.

In cold climates insulating the floor may also require extra insulation on plumbing to protect it from freezing in the colder crawl area. In warm weather insulating the floor loses the cooling effect of its location over the cooler ground surface.

In the crawl space insulation detail (sketch at left), beware of:

• Crawl space moisture problems: contemporary best building practices call for installation of a 6-mil poly vapor barrier over dirt floors of crawl spaces; run the poly at least part-way up the foundation wall sufficient to cover the portion of the wall that is below-grade.
  
  Crawl space ventilation does not necessarily reduce crawl space moisture levels and in some weather conditions it can actually increase crawl space moisture, condensation, and mold risks. That's why modern best construction practice converts crawl spaces from the old "vented" design to new "closed, conditioned space". Just be sure to also identify and correct roof drainage or surface runoff problems that are sending water into the crawl area.
• Hidden termite damage to the building - we have found termites and on occasion other wood destroying insects attacking the building sills, rim joist, and floor framing when the poly vapor barrier and insulation extend from the floor to the building wooden sills. Insulation provides a hidden path from soil top into the wood framing. In the sketch, the use of poly under the insulation reduces but does not eliminate this risk.
• Hidden mold contamination in buildings can be severe when fiberglass insulation is used in damp locations such as crawl spaces. See Crawlspace Mold Advice and see FIBERGLASS MOLD.

Additional links to articles on good crawl space design and solving crawl space problems are provided below.

Insulation Advice for Full Basements

Mr. Bliss prefers insulation on the basement interior for the same reason that apply to crawl spaces, including avoiding frozen pipes. He suggests using a section of rigid foam insulation to separate off hard-to-insulate basement locations such as steel bulkhead basement walkout doors. Our photograph (left) shows sytrofoam insulating foam board used on the inside of a basement foundation wall. We prefer to use solid foam insulation in any below-grade location that is at risk of period high moisture, because our field and lab work have shown up frequent hidden toxic mold reservoirs in fiberglass insulation that has been used in those locations. See Mold in Fiberglass Insulation for details.

Insulation Advice for Mudrooms

In the articles above, the author suggests that attached spaces such as mudrooms that get frequent use should be inside the building's thermal envelope. If a mudroom is excluded from the building envelope of conditioned space (heated, dried, or seasonally cooled and dehumidified), there is an increased risk of mold since the rooms receive household moisture but little heat.

If the mudroom or airlock entry space is used rarely, such as an enclosed porch, you can go either way - insulating it or not, but if an attached room on a house is left unheated, besure that it is also isolated from the home's moisture by proper placement of vapor barriers.

Insulation Advice for Sunspaces

Mr. Bliss points out that sunspaces are always insulated from the outdoors, but asks "... should they be insulated from the house?"

In climates that have frequent periods of cold and cloudy weather, it's a good idea to insulate and seal between the sunspace and the house - assuming that you are not trying to keep heat in the sunspace to keep plants alive through cold weather. If plants are being maintained in a sunspace you may need to heat that area as well.

Insulation between the house and the sunspace can be less than that in other house walls facing directly outdoors because of the buffering effect of the sunspace. But the air space between the sunspace and the house should be tight to keep greenhouse moisture from entering and causing mold or other problems in the main building.

In sunny climates that can keep the sunspace mass warm all winter, uninsulated walls between the sunspace and the main building are fine. Night insulation is a good idea for these sunspaces since the sunspace glass is part of the thermal envelope.

Insulation Tips for Stairwells and Other Interior Discontinuities or "Bumps" in a House

Interior walls, built-in cabinets, stairs, and plumbing fixtures can disrupt the continuity of the building's thermal envelope or shell. Good planning during construction can avoid these problems by making sure that insulation and vapor barriers are properly placed. In retrofits to older buildings it's not so easy, Mr. Bliss notes.

For insulation retrofit on older buildings don't forget to watch for, evaluate, and if appropriate open and insulate these areas. A common example that we see on older homes is the failure to insulate below attic stairs whose ceiling is exposed to the otherwise heated and insulated main area of the home.

In our attic stairwell photo (left) the house exterior wall and the area underneath the stairs themselves were uninsulated, leaking heat out of this home.

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

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INSULATION & VENTILATION INSPECTION & IMPROVEMENT
AIR BYPASS LEAKS
AIR LEAK DETECTION TOOLS
AIR LEAK MINIMIZATION
AIR SEALING STRATEGIES
ASBESTOS IDENTIFICATION IN BUILDINGS
ATTIC LEAKS, CONDENSATION & ATTIC MOLD
BATHROOM VENTILATION
BASEMENT LEAKS Moisture or Mold
BASEMENT HEAT LOSS
BLOWER DOORS & AIR INFILTRATION
BRICK LINED WALLS
BUCKLED FOUNDATIONS due to INSULATION?
CATHEDRAL CEILING INSULATION
CRAWL SPACES
  Crawl Space Dryout Procedures
  Crawl Space Safety Advice
  Crawlspace Mold Advice
  Media Blasting for Mold Removal
  Mold on Dirt Floors
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
ENERGY SAVINGS in BUILDINGS
ENERGY SAVINGS PRIORITIES
ENERGY SAVINGS RETROFIT CASE STUDY
ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE
ENERGY SAVINGS RETROFIT OPTIONS
ENVIRONMENTAL HAZARDS
FIBERGLASS INSULATION
FIBERGLASS HAZARDS
FIBERGLASS MOLD
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FREEZE-PROOF A BUILDING
HEAT LOSS CALCULATIONS
HEAT LOSS in BUILDINGS
HEAT LOSS DETECTION TOOLS
HEAT LOSS INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HOUSEWRAP AIR & VAPOR BARRIERS
HOUSEWRAP - TYVEK INSTALLATION DETAILS
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INSULATION & VENTILATION INSPECTION & IMPROVEMENT
INSULATION CHOICES
INSULATION FACT SHEET- DOE
INSULATION IDENTIFICATION GUIDE
INSULATION LOCATION for CAPES, CRAWLSPACES
INSULATION MATERIAL IDENTIFICATION GUIDE
INSULATION MOLD
INSULATION R-Values & Properties
Insulation Values of Log Home Walls
INTERIORS of BUILDINGS
Mold Growth Resistance of Foam Insulation
MVOCs & MOLDY MUSTY ODORS
ODORS & SMELLS DIAGNOSIS & CURE
RADIANT BARRIERS
ROT, FUNGUS, TERMITES
  TERMITE SHIELDS vs TERMITICIDE
ROT, TIMBER FRAME
SOLAR ENERGY SYSTEMS
SOUND CONTROL in BUILDINGS
STAIN DIAGNOSIS
THERMAL MASS in BUILDINGS
THERMAL MASS in UPSTAIRS
THERMAL TRACKING & HEAT LOSS
VAPOR BARRIERS & AIR SEALING at BAND JOISTS
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VAPOR BARRIERS & HOUSEWRAP
VAPOR CONDENSATION & BUILDING SHEATHING
VENTILATION in BUILDINGS
WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING

• Solar Age Magazine was the official publication of the American Solar Energy Society. The contemporary solar energy magazine associated with the Society is Solar Today. "Established in 1954, the nonprofit American Solar Energy Society (ASES) is the nation's leading association of solar professionals & advocates. Our mission is to inspire an era of energy innovation and speed the transition to a sustainable energy economy. We advance education, research and policy. Leading for more than 50 years. ASES leads national efforts to increase the use of solar energy, energy efficiency and other sustainable technologies in the U.S. We publish the award-winning SOLAR TODAY magazine, organize and present the ASES National Solar Conference and lead the ASES National Solar Tour – the largest grassroots solar event in the world."
  
• Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
  Excerpts with updates and annotations expanding the original Best Practices Guide text can be found in the online review and book summary at BEST CONSTRUCTION PRACTICES GUIDE and also at DECK & PORCH CONSTRUCTION, at INDOOR AIR QUALITY IMPROVEMENT GUIDE, and in other articles found at InspectAPedia.com such as HOUSEWRAP AIR & VAPOR BARRIERS, SOUND CONTROL in BUILDINGS, and other topics.
• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Passive Solar Design Handbook Volume I, the Passive Solar Handbook Introduction to Passive Solar Concepts, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v1.pdf
• Passive Solar Design Handbook Volume II, the Passive Solar Handbook Comprehensive Planning Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v2.pdf [This is a large PDF file that can take a while to load]
• Passive Solar Handbook Volume III, the Passive Solar Handbook Programming Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v3.pdf
• The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083 is available at Amazon.com and via the The Passive Solar Design and Construction Handbook, Steven Winter Associates (Author), Michael J. Crosbie (Editor), Wiley & Sons, ISBN 978-047118382 or 0471183083 is available at Amazon.com and via the InspectAPedia Bookstore
• "Passive Solar Home Design", U.S. Department of Energy, describes using a home's windows, walls, and floors to collect and store solar energy for winter heating and also rejecting solar heat in warm weather.
• "Solar Water Heaters", U.S. Department of Energy article on solar domestic water heaters to generate domestic hot water in buildings, explains how solar water heaters work. Solar heat for swimming pools is also discussed.
• "Heat Exchangers for Solar Water Heating Systems", U.S. DOE describes the types of solar water heater heat exchange methods between the sun and the building's hot water supply
• "Heat-Transfer Fluids for Solar Water Heating Systems", U.S. DOE, describes the types of fluids selected to transfer heat between the solar collector and the hot water in storage tanks in a building. These include air, water, water with glycol antifreeze mixtures (needed when using solar hot water systems in freezing climates), hydrocarbon oils, and refrigerants or silicones for heat transfer.
• "Solar Water Heating System Maintenance and Repair", U.S. DOE
• "Solar Water Heating System Freeze Protection", U.S. DOE,using antifreeze mixture in solar water heaters (or other freeze-resistant heat transfer fluids), as well as piping to permit draining the solar collector and piping system.
• "Scaling and Corrosion in Solar Water Heating Systems", U.S. DOE
• www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12850 is the base U.S. DOE website for these articles
• "Active Solar Heating Systems", U.S. Department of Energy, including
• "Radiant Heating Systems" U.S. DOE
• "Absorption Heat Pumps & Coolers", U.S. DOE
• "Solar Air Heating" U.S. DOE also referred to as "Ventilation Preheating" in which solar systems use air for absorbing and transferring solar energy or heat to a building
• "Solar Liquid Heating" U.S. DOE, systems using liquid (typically water) in flat plate solar collectors to collect solar energy in the form of heat for transfer into a building for space heating or hot water heating. The term "solar liquid" is used for accuracy, rather than "solar water" because the water may contain an antifreeze or other chemicals.

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