What is the Best Attic Insulation Product for My Home?
Adding attic insulation is a no-brainer for homeowners who want to keep comfortable year-round while saving energy. In fact, this measure is required in to be installed or approved whenever a home is bought or sold in Berkeley, CA. Insulation helps slow the movement of heat, keeping your home warmer in winter and cooler in summer. Insulation is measured by its ability to resist heat transfer, or R-value. Depending on your home’s construction and what projects are planned or ongoing, one of several products may be best for your home:
Blown Cellulose Insulation
Blown cellulose insulation is a great product for most attic insulation projects. It is made from recycled paper and is treated with borate, which acts as a flame retardant and deters mold, mildew, and pests. Although some studies link very high levels of borate exposure to kidney and reproductive problems in rats, borate-stabilized cellulose is generally considered to be the least harmful insulation product in terms of embodied energy, environmental impact, and occupant and installer health.
Loose-fill blown insulation is more effective than fiberglass batt insulation for ensuring complete and uniform insulation coverage, because the small fibers fill non-uniform framing cavities and areas around wiring, ducts, plumbing, and other objects in the attic. When properly installed, cellulose insulation should perform well without degradation for 25 years or more. In mild climates, R-38 insulation is required by building codes. In harsher climates, R-49 insulation is required.
If you store items in your attic, or have any equipment in your attic that needs to be accessed, a raised platform may need to be constructed in your attic. The platform should be at least as tall as your insulation so that it does not decrease the performance of your insulation. Also, it is good to complete other attic projects, such as re-wiring, before installing cellulose attic insulation – the electrician who comes along next year won’t treat your insulation with as much care as the crew that installed it, and workers can easily damage the insulation job if they aren’t careful.
Spray Foam Insulation
If your home has a large area of vaulted ceiling with no attic, spray foam is an excellent performing insulation material. Spray foam is fossil fuel based and often contains 5-15% soy, corn, or other organic content. Spray foam is highly effective because it seals the surface it’s applied to, preventing conditioned air from leaking out of your home in one step. Like cellulose, spray foam is not a consolidated product, so it covers all the nooks and crannies better than fiberglass batts. Closed cell spray foam also has higher R-value per inch than many other insulation products, such as fiberglass batts, so you can get more insulation performance in confined spaces like two-by-six ceiling cavities.
Spray foam is worth considering if your home has heating or cooling equipment located in the attic. Since spray foam is installed against the roof of the home, rather than the ceiling, the attic becomes part of the conditioned space of the home, so any efficiency losses from ducts are staying “inside” the house, not “outside”.
Since spray foam is comparatively expensive, fossil fuel based, does emit greenhouse gases during installation, and can be toxic if proper installation guidelines are not followed, spray foam is not recommended for a typical house with an empty attic between the ceiling and the roof. However, its superior performance makes it a great candidate to install in cathedral ceilings or if your attic needs to be conditioned.
If you do decide to install spray foam insulation in your attic, be sure to remove any old insulation and to sanitize if you find any rodent droppings or other health contaminants – you don’t want to seal those unhealthy particles in the house with you! Also, remember that most houses need to be vacant and ventilated for three days after a spray foam job, because off-gassing occurs as the foam cures.
Denim Batt Insulation
If you have areas of cathedral ceiling and want to use the material with the lowest environmental impact and health considerations, consider using denim batts to insulate. Denim batts insulate as well as fiberglass batts, but are made from recycled cotton fiber and are treated with borate.
Furthermore, because of their density they do a better job of stopping air movement than traditional fiberglass batts.
Copyright September 2014 by Advanced Home Energy
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