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A Guide to Insulation Jargon

06 December 2019

It becomes painfully obvious this time of the year if your home’s insulation is lacking.  A quick online search for ways to remedy the situation can fill your computer screen up with terms specific to home insulation that you’ve likely never heard of.  Here’s our guide to commonly used insulation terms that you’ll likely hear your insulation contractor use and what they mean.

Attic Air Sealing: Attic air sealing is the thorough process of finding and addressing areas of an attic that have permitted outside air to filter in.  Can lights, false soffits, and bath fan penetrations are all areas that deserve consideration.  Cracks and holes can be filled in with spray foam, patches, and weather-stripping.

Blower Door: A blower door is a diagnostic tool utilized by insulation contractors to change the pressure within a house so that home energy issues are magnified enough to be easily diagnosed.  A blower door looks like a screen door with a fan built into it.

Learn More About Blower Door Testing: 

Building Envelope: A home’s building envelope is the outer shell that fends off the effects of Mother Nature. Components include roofing, exterior doors, subflooring, and exterior walls.

Cellulose Insulation: Cellulose insulation is made from wood or paper.  With a feather-like consistency, it is often blown into spaces where it is needed.  It’s lauded for its ability to conform around obstacles such as ducts and wires.

Fiberglass Insulation: Fiberglass insulation is comprised of miniscule glass fibers.  It frequently comes in batts and rolls.  It is a cheap form of insulation and is prone to mold and moisture issues and does only a fair job of preventing roof leaks.

Hot Roof: In a hot roof, insulation is installed in close proximity to the roof sheathing and closed off to exterior air flow.  Because the roof is unvented, the surface temperature of the roof is slightly warmer than vented roofs. When your attic is filled with spray foam insulation to create a hot roof, your attic’s temperature rises because the thermal envelope is shifted to the underside of your roof because ventilation is not present.

hot roof

R-Value: This is the grading system used to rate how effective the insulation is.  The higher the number, the better the R-Value is.  Because of the extreme temperatures we experience in the Twin Cities and Western Wisconsin, it is recommended that an attic have a minimum R-value of 50.

Spray Foam Insulation: Spray foam insulation is a mixture of resin and chemicals.  As the insulation is applied, it expands.  It has a high R-value and allows for minimal air infiltration.

spray foam insulation

Stack Effect: The stack effect causes your home to draw air from your basement up to your attic through your walls during the winter months.  This is because the colder exterior air is denser and enters your home through gaps in the lowest level of your home.  Upon entry, it creates an upward circulation of warm air from your furnace through your floors and ceilings until it reaches your attic where it exits the home via areas that have not been fully sealed off. In the summer months, the opposite is true and outside air enters through your crevices.  The warm air is pulled down your walls to your home’s lowest level where the air escapes through exterior gaps in your home.

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spray foam insulation

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