Blown fiberglass vs. cellulose

Replies to This Discussion

Permalink Reply by Armando Cobo on March 1, 2012 at 4:51am

They are both good insulation choices, if installed correctly, however, cellulose has a much lower global warming potential of any insulation, it is made with post-consumer recycled material, it is treated with borates for fire and insect protection and has low toxicity to the homeowner as well.

Permalink Reply by Joseph Lamy on March 1, 2012 at 7:31am

VERY cool chart. Where is the data to support such a quick payback for cellulose? What one pays for heat/ cool is a factor, the rest of the house is a factor, and so please document your lines.

Cellulose has been my favorite for many reasons for years: better performance in summer, lower environmental impact in producing the stuff, bug and vermin repellant features of the product, fire retardance, not to mention the absence of the carcinogenic likelihood as the WHO says accompanies FG.

Permalink Reply by Armando Cobo on March 1, 2012 at 4:43pm

I’m sorry, in my commotion of writing my reply and leave for work I should have included the source of the picture. It came from an Environmental Building News article by Alex Wilson, who did a study with Building Science Corp. about insulation payback. To read “Avoiding the Global Warming Impact of Insulation” blog go to EBN Jun 2010.

Permalink Reply by Sean Lintow Sr on March 1, 2012 at 5:00am

Let me preface this by saying I have not seen this machine in use, or even the new versions where they combine blown or batt with a proprietary sealing system. With that said, nothing really has changed - FG is a great product for insulation as long as it is installed perfectly. This includes making sure that it is completely enclosed on all 6 sides, and air is not allowed into the cavity. I would think that using this product would make it easier to get the "perfectly" installed status as compared to many of the batt installations we all see. With that said, one item to remember is that FG loses RValue the hotter it gets.

If given a choice between cellulose & FG - I would go with cellulose in almost every case. Now if you are wondering if one can bypass air sealing with cellulose the answer is no

Permalink Reply by Randy Wilkerson on March 1, 2012 at 5:07am

We have found that cellulose breaks down faster over time than fiberglass does. We blow only fiberglass at this time.   This is secondary but the fiberglass lovers will tell you why theirs is the best and well as the cellulose lovers.  

Permalink Reply by Robert Riversong on September 4, 2012 at 8:31pm

Cellulose doesn't break down. It is designed to settle about 10% after initial loose-fill attic blow.

Permalink Reply by Paul Lasicki on March 1, 2012 at 5:18am

Thanks guys for your input. The reason why I'm going with the atticcat at this time is that I am a one man operation working out of a van ( I am a BPI accredited Home Performance contractor w/ Energy Star, BA and Envelope certs.) and find that with a helper I'll be able to blow attics myself without the start up costs involved with setting up a cellulose blower and truck. At this point it's more of a financial decision.  Maybe in the future I'll be able to incorporate some cellulose blowing capabilities.

Permalink Reply by Patrick Michaelyan on March 1, 2012 at 7:02am

I used to be in your shoes Paul. With a helper and a rather small financial investment, you can blow cellulose at a better cost (and outcome) than blown-in FG.

Check out the Accu1 9218 machine, it's great for simple applications (and it has a remote control).

At the end of the day, if you can spend 2-3 hours to blow an attic with cellulose rather than spend half a day or more by yourself (or with a really cheap blowing machine), then you will find that this is how you can work smart and make better profits. 

Permalink Reply by Patrick Michaelyan on March 1, 2012 at 6:57am

Paul, this is probably based on a bit of bias here, but I am for blown-in cellulose over FG all day long. (Note: Proper and thorough air sealing is a prerequisite regardless).

Some spots are just darn hard to seal, and with the cellulose you get a partial air seal if installed at a certain density and\or depth.

The real key is to "dam off" around accesses, heat sources, etc. if you wish to have a clean and effective install.

Patrick

Permalink Reply by Pat Dundon on March 1, 2012 at 9:35am

i am not familiar with 'attic cat', but any blown insualtion is susceptible to failure due to infiltration and convective looping.  some less than others, but all suffer in some situation.  the thing is in a forum like this when you pose this question it is like going to a NASCAR event and saying Chevy beats Ford every time.   Everyone has an opinion, some are more passionate than others, and all are mostly right and a little wrong. 

it is up to you to go back to the fundamentals and think about your housing stock, availability of equipment and talent, practicality of the install, and what is required to produce and effective solution.  any insulation contractor today who only provides one product is either dishonest or ignorant.  you cannot do everything WITH fiberglass, cellulose, board foam or spray foam, but you also cannot do everything WITHOUT fiberglass, cellulose, board foam, and spray foam. 

Permalink Reply by Patrick Michaelyan on March 1, 2012 at 9:57am

I'll accept Pat's answer.

The tough part is determining the right combinations, and how to apply them.

(P.S. I still think that blown-in FG really is an inferior product compared to cellulose.)

Permalink Reply by Robert Riversong on September 4, 2012 at 8:38pm

You're right that a one-product installer will always say his product is the best, but it's not true that you can't do everything with a single product, and cellulose is superior in every respect to fiberglass. It has less embodied energy and global warming potential, is 100% non-toxic to humans but toxic (with borates) to all common household insects and an irritant to rodents, it's very fire retardant (with borates), it has better sound-deadening qualities, far better air-sealing qualities, and higher R/inch.

There is not only no convective air movement in cellulose, but tests have shown that as little as two inches of blown cellulose on top of blown fiberglass will stop the convection within the fiberglass. And third-party testing has proven that dense-pack cellulose qualifies as a firestop because it is so resistant to air movement (I've used it many times in double-wall houses with balloon framing).

P.S. I'm not involved in the cellulose industry. I'm a 30-year designer/builder of healthy super-efficient homes and and instructor in sustainable design and hyrgo-thermal engineering. 

• ‹ Previous
• 1
• 2
• Next ›
• Page