Fiberglass vs. Cellulose Insulation

By
Home Inspector with Jay Markanich Real Estate Inspections, LLC 3380-000723

I have understood from insulators that in very cold temperatures fiberglass insulation will actually absorb heat from the house.  I have never been able to prove that.  Of course, the cellulose insulation guys will suggest that their insulation be blown in over the fiberglass, and problem solved!

What's cellulose insulation?  Super chewed up newspaper!  If you look at it closely you can see red, blue and green flecks from the funnies!  They treat it with Boric acid, so bugs* won't eat it and burrow inside, and blow it in.  It is very effective because when laid properly it leaves few gaps.  It has a better R-value than fiberglass (3.7 vs. 3.14 per inch) and can be blown into many areas hard to reach with fiberglass.

IT IS VERY UNUSUAL TO SEE BOTH CELLULOSE AND FIBERGLASS INSULATION PUT SIDE BY SIDE INTO A HOUSE WHEN FIRST BUILT.  One area may be of one or the other (like steeply-sloped cathedral ceilings, which work best with rolled fiberglass batts) but not side by side.

On a recent thermal investigation, with the typical hot/cold complaints, I saw patterns like this.  Red/yellow indicates warm, blue/purple indicates cold.

Not unusual - clearly there is rolled fiberglass insulation where edges have come up, or there are gaps, and heat is escaping.  A moisture meter indicated no moisture.

But what was unusual was that this pattern would be on one small aspect of the ceiling and the rest of the ceiling would be perfectly insulated.  That is not typical.

I was surprised to get into the attic and see fiberglass and cellulose installed side by side, and apparently at the same time!

It was unusual to see one small area, maybe only 4' long, covered with fiberglass, with cellulose blown all around, but not on top of, that fiberglass.  I have never seen that before!

This was a very cold morning.  I like early mornings for IR investigations because there is no influence by the sun.  The attic space was about 12F!  I think my camera is actually looking at fiberglass insulation absorbing heat! 

This is a small piece of fiberglass with cellulose all around.  Clearly the fiberglass is not insulating as well.  Those warm spots are 61F, so heat is moving upward and into the attic space via the insulation.  And moving fast!

My recommendation:  if you have opportunity to select insulation for your new house, cellulose is affordable and very effective.  If you want to add insulation to your existing insulation, cellulose is the same.

And when you add insulation to your existing, what you add is cumulative.  If you add R15 to an existing R30 the result is R45.  And R45 is very good insulation, especially if all the bypasses, gaps and holes are filled!

* Crazy, nutsy squirrels included...

 

 

 

Posted by

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560

www.jaymarinspect.com


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Rainmaker
455,517
John Mulkey
TheHousingGuru.com - Waleska, GA
Housing Guru

Jay - Great info that your infrared camera is able to confirm.  (Perhaps you could use the camera to "analyze" my latest blog post. It seems to have generated a lot of heat.)

Feb 16, 2011 01:56 AM #25
Rainer
51,576
Patrick Schorle
Pacifica Real Estate Inc. - Sidney, BC
Patrick Schorle

Thanks Jay for a very interesting and informative post!

Feb 16, 2011 05:41 AM #26
Ambassador
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Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Jay, all insulations "conduct" heat---the best ones make it seem like they don't---fiberglass does a great job of conducting heat---better than most----right along with all its infiltration issues.

Feb 16, 2011 09:17 AM #27
Rainmaker
150,469
Virginia Gardner
Roy Wheeler Realty Co. - Charlottesville, VA
Realtor, Charlottesville, Serving Central Virginia

Wonderful post, thank you!  I love your show-and-tell!

Feb 16, 2011 10:17 AM #28
Rainmaker
226,377
Suesan Jenifer Therriault
JTHIS-Professional Home Inspection Team - Blakeslee, PA
"Inspecting every purchase as if it were my own".

Cellulose is definitely the way to go if you want to hold in heat and cut down on air movement. I’m not a big fan of fiberglass insulation in any form. 

Feb 16, 2011 01:22 PM #29
Rainmaker
354,833
Damon Gettier
Damon Gettier & Associates, REALTORS- Roanoke Va Short Sale Expert - Roanoke, VA
Broker/Owner ABRM, GRI, CDPE

Jay,  thanks for writing this blog.  It will be passed onto my clients now, and in the future.

Feb 16, 2011 01:24 PM #30
Rainer
407,122
Randy Ostrander
Lake and Lodge Realty LLC - Big Rapids, MI
Real Estate Broker, Serving Big Rapids and West Central MI

Love the thermal imaging Jay and I have always wonder about which would be better.

Feb 16, 2011 10:19 PM #31
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Pat - rip them to pieces and start spreading!

Barbara - I had a post about that two days ago.  

http://activerain.com/blogsview/2135548/icynene-do-you-see-nene-

Be sure to read the links to my previous icynene posts.

Yes Don.  Always paper instead of plastic.  It degrades!

John - I just looked, thinking I knew what you were talking about!  Looks like you are the local myrmidon!  And I should get that home inspection deduction.

Feb 16, 2011 11:11 PM #32
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Glad you enjoyed it Patrick.

Charlie - fiberglass actually sucks it from the house!  Everything conducts heat, even the dead, but not vampires.  Either way, you are right!

Virginia - do I get a gold star?

Sue - they used fiberglass insulation to fill my aunt's thoracic cavity in the 30's when they removed one of her lungs due to TB.  She died 3 years ago, so it worked well!  So there...

Feb 16, 2011 11:13 PM #33
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Damon - it's not often that you are given the opportunity to prove something you have always heard!

Randy - there are lots of suggestions out there.  Actually the best insulation is asbestos!

Feb 16, 2011 11:14 PM #34
Rainer
78,096
Bill Saunders, Realtor®
Meyers Realty - Hot Springs, AR
www.BillSellsHotSprings.com

Jay,

Love the post. Thanks once again, I'll be heading over to your others!

all the best...

Feb 19, 2011 01:04 AM #35
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Thanks Bill for all your stopping by!

Feb 19, 2011 05:16 AM #36
Rainmaker
1,942,891
Andrew Mooers | 207.532.6573
MOOERS REALTY - Houlton, ME
Northern Maine Real Estate-Aroostook County Broker

Would not fill the eave. I don't want my attic more than 5 degrees warmer than outside temperature cause condensation, raining in side a home moisture is a very bad thing, condition.

Feb 20, 2011 12:32 AM #37
Ambassador
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Barbara-Jo Roberts Berberi, MA, PSA, TRC - Greater Clearwater Florida Residential Real Estate Professional
Charles Rutenberg Realty - Clearwater, FL
Palm Harbor, Dunedin, Clearwater, Safety Harbor

Jay - You are such a wonderful source of knowledge! I wish you were down here in Florida inspecting homes!

Feb 20, 2011 03:35 AM #38
Rainmaker
238,410
Angelia Garcia
Pure Realtors - Dallas, TX

I like your reading your posts.  I always learn something new.  Then I forget it later.  HA!

Feb 20, 2011 04:14 AM #39
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Andrew - what works in one area might not work in another!  You speak from geographic experience!

Barbara-Jo - I don't think I could do inspections down there until I had observed a hundred or so!  I'm sure it's different!

Angelia - so then you need to keep coming back over and over and learning more!

Feb 20, 2011 06:14 AM #40
Rainmaker
233,467
Reuben Saltzman
Structure Tech Home Inspections - Minneapolis, MN
Delivering the Unbiased Truth.

Great post, Jay.  I have this exact same topic on my list of things to blog about.  When I do, I'll have to change the title of the post ever so slightly.  Maybe "Cellulose vs. Figerglass Insulation" :)

Feb 20, 2011 01:34 PM #41
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Good idea Reuben. 

And it is rare to be able to see the two insulations working side by side.

Feb 20, 2011 09:28 PM #42
Rainmaker
579,727
Chris Smith
Re/Max Chay Realty Inc., Brokerage - New Tecumseth, ON
South Simcoe, Caledon, King, Orangeville Real Esta

Wow Jay, great information.  It is amazing how we learn things that changes what was conventional wisdom...

Feb 21, 2011 11:38 PM #43
Rainmaker
1,843,815
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

Chris - conventional wisdom sometimes comes about because of the longevity of something without new substitutes.  In this case both of these insulations have been around a while!

Feb 21, 2011 11:43 PM #44
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Rainmaker
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Jay Markanich

Home Inspector - servicing all Northern Virginia
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