In our retrofit business we take a much stronger stance on quality of installation than we do on product type.

Insulation Materials

The goal of this section of our web site is to help you to be able to identify the type or types of insulation materials you have in your attic and acquire a basic understanding of the insulation’s properties. 

Advanced Insulation is not interested in promoting one type of insulation at the expense of another in this section of the web site.  We take an objective look at commonly installed insulation materials in existing homes.  We conclude this section of the web site with a brief discussion on health and safety issues surrounding different insulation materials where we attempt to dispel some of the misconceptions surrounding different insulation materials. 

At Advanced Insulation we know that in the marketplace there are a lot of people with strong opinions about insulation.  We believe that many of the manufacturers and sale people who are sowing confusion in the marketplace are more interested in market share than they are an honest discussion about the pros and cons of different materials. 

In our retrofit business we take a much stronger stance on quality of installation than we do on product type.  We know that the materials commonly used in existing homes can be undermined by poor installation.  We also know that small thermal defects can have a huge impact on R-value.  This is why quality of installation is often more important than the type of material being installed.

Insulation Selection in New Construction

Why do you have fiberglass batts, cellulose or blown fiberglass in your attic?    Did the builder make a choice based on his opinion of what was a superior product?   The answer in all likelihood was made on the basis of price and what his insulation contractor offers. 

If there is no access in the attic to blow in either cellulose or fiberglass, up until recently the only choice was to install fiberglass batts.  The fiberglass batts can be installed before sheet rock installed, which makes them the product of choice in tight attics.  In new construction Advanced Insulation is now spraying foam in some attics as opposed to installing fiberglass batts (Link to foam )

Common Insulation

You'll find three commonly used types of insulation in attics: blown-in cellulose, blown-in fiberglass, and fiberglass batts.  Although we see rock wool in older homes we assume it has been a couple of decades since rock wool has been blown in attics in Arizona.

Blown-in Cellulose Insulation    

The grey material with flecks of white is blown cellulose insulation

Blown cellulose is a grey insulation material commonly blown in Arizona attics.  On a rare occasion we’ll see cardboard colored cellulose in older homes.  Although it is made from recycled news print you wouldn’t know it without looking very carefully because it has been converted back to a cellulose fiber.

“The word cellulose comes from the French word for living cellule and glucose, which is sugar.”  Wikipedia    Cellulose is the structural component of the primary cell wall of green plants.  For industrial use, cellulose is mainly obtained from wood pulp and cotton.  It is mainly used to produce cardboard and paper. 

Cellulose insulation is 75%-85% recycled paper, usually post consumer waste and for this reason is a favorite of the green movement.  The remaining percentage is the fire retardant which is either boric acid or ammonium sulfate or a blend of the two

Cellulose has an R-value of 3.7 per inch.  It will settle when installed in attics and if installed correctly this settling is factored into the installation.  For instance depending on whose product we are blowing, the coverage chart will call for an additional 15% - 20% to account for settling.  For example we’ll blow 9.8" of cellulose, which we know will settle to 8" or about 15% to 20%. 

The problem that Advanced Insulation has had with cellulose is that some coverage charts are overly optimistic in regard to coverage.  This is especially true of stabilized products.  For more information on the issues of cellulose coverage charts see the article Michael Uniacke wrote for Home Energy Magazine.

Blown-in Fiberglass

Fiberglass insulation is manufactured from silica.  Silca is most commonly found in nature as sand and quartz.  The silca is melted and then spun into a glass fiber which is used in the manufacturer of fiberglass batts and blowing wool.  The fibers trap air and that is how the R-value is derived. 

Blown fiberglass comes in three common colors: white, pink or yellow and the colors simply identify the manufacturer.  Blown-in fiberglass insulation in attics typically has an R-value of 2.5 per inch.  The density of the blown-in fiberglass determines the R-value just like it does for a batt.  This is why we can purchase a 3.5” batt with R-values of 11, 13, and 15. 

    
A newer white blown-in fiberglass                   An older yellow blown-in fiberglass                         

The older versions of blown-in fiberglass were itchy and often would make our estimators cough during attic inspections.  Today the material has evolved remarkably.  Some of the blown fiberglass insulation products feel more like a cotton fiber than it does a glass fiber. 

There is a potential problem with some blown fiberglass is that it can be fluffed; i.e. whipping the blown fiberglass up with air, which compromises density and thus R-value.  Based on limited experience performing core sampling we don’t believe fluffing is a problem in Arizona. 

Batt Insulation

A fiberglass batt being installed in an attic

Fiberglass batt insulation typically comes in pieces.  The problem with fiberglass batts is they are installed by people who are rewarded for the quantity and not quality of installation.  The R-value of fiberglass batts can be easily undermined by sloppy installation.  Most insulation company’s piece rates are not high enough, so all of the focus is on production.  In new construction Advanced Insulation pays higher piece rates in order to strike a balance between quantity and quality.  Link to JLC Fiberglass Insulation article

Rockwool / Vermiculite

To the best of our knowledge blown-in rockwool insulation and poured-in vermiculite are two products that are no longer being installed in the Arizona.  Since we do occasionally come across these two products in much older homes, we decided to provide a brief description of both materials.

We come across blown-in rock wool insulation products in houses built in the 60’s and 70s.  Based on our numerous trips into existing homes, we suspect blown-in rock wool insulation has not been blown in attics in Arizona since with any frequency since the late 70’s.  We also have seen green and mostly black rock wool Arizona insulation.  The R-value of blown-in rockwool ranges between R-2 and R-3 per inch. 

Every once and a while we run into an older houses built in the 50’s or earlier that have poured in vermiculite insulation.  Vermiculite is a naturally occurring mineral.  “It has the unusual property of expanding into a worm like accordion shaped pieces when heated.  The expanded vermiculite is a light-weight, fire resistant, absorbent, and odorless material.”   There is the potential for some vermiculite to be contaminated by asbestos.  We encourage you to visit the EPA website and do a search on vermiculite, if you have vermiculite in your attic.

Foam Insulation

Half pound foam being sprayed to underside of roof sheathing.

Advanced Insulation does spray foam insulation on the underside of the roof sheathing in new construction (link to foam section).  This code approved configuration is called an unvented attic with cathedralized insulation.  Although we can do retrofit insulation in existing homes, we do not encourage it because it both very expensive and hard to execute correctly in a house where the sheetrock is already in place.

Health Safety & Insulation Products

Advanced Insulation is committed to installing quality products in a safe manner.  With the exception of the kraft faced paper on some fiberglass batts when installed in the wrong areas, we do not believe that the blown in cellulose and fiberglass will compromise the health, safety, and or value of your home. 

In the battle for market share some manufactures will try to convince you that cellulose insulation is a fire hazard and that fiberglass insulation is a carcinogen.  Our thorough review of existing research dispels these myths.  If indeed these myths were substantiated with facts, trial lawyers would have put these industries out of business a long time ago. 

In regard to fire safety, the only insulation material we are truly concerned about is kraft paper on some fiberglass batts.  The paper on kraft faced batts can pose a risk, if installed against, chimney, flue pipes and some recessed light fixtures.  We take extra care to train our installers how to safely install kraft faced batts.