What I'm Seeing Now

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Fiberglass vs. Cellulose Insulation

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...

 

 

 

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


Comment balloon 44 commentsJay Markanich • February 16 2011 06:49AM

Comments

  Cosmo and Magic...our feline roommates are now starting their own paper chewing for Cellulose business...Cosmo is especially adept at chewing and now....he will be worth his weight in kitty litter...good tip Jay...as always.

Posted by Sally K. & David L. Hanson, WI Realtors - Luxury - Divorce (EXP Realty 414-525-0563) over 8 years ago

Hi Jay,

I have been told that the spray in foam insulation is a good product too.  Here in the Northeast they recommend it as it is great to prevent possible mold and mildew.  The only problem is that it is 3 times the price of fiberglass.

 

Laurie

 

Posted by Laurie C. Bailey-Gates, ABR, SFR (Robert Paul Properties) over 8 years ago

Save on heating in the winter, and electric for AC in the summer.  Win win.  Let's get some more insulation.

Posted by Kenneth Cole, NYS Licensed Real Estate Salesperson (Weichert Realtors Appleseed Group, 2043 Richmond Ave. S.I.N.Y. 10314. office phone 718-698-9797, Appleseedhomes.com -) over 8 years ago

Sally - I saw a news story of a cat who steals things from the house (clothing, stuffed animals, everything) and takes them to a stash point on the roof.  In three years he has stolen 600 things!  Put in the right spots, that stuff might make good insulation also.

Be sure to throw some funnies into that chewed mix, and then you can sell it as cellulose insulation!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Laurie - I had a post on that a couple of days ago.

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

In there you will see links to two other posts of mine a year ago.  You are right - it's effective stuff and very expensive!

Ken - it is very effective and worth its weight in gold.  Of course, it isn't very heavy.  If it was I would take the gold...  geez, I might STILL take the gold!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Good to know. Maybe all the old newspapers my Dad saved may be useful after all :)

Posted by Retired Notworking over 8 years ago

Hi Jay,

The IR photos are very revealing. I never knew fiberglass could absorb heat. Laurie #2 mentioned spray foam. Do you have any experience with that product. They recommend filling the eave entirely. I think this will lead to a breathing problem like we had in the 70's. Any thoughts?

Posted by John McCarthy, Realtor - Seacoast NH (Bean Group Portsmouth NH) over 8 years ago

Colleen - start spreading them around!  When I was a kid, we would take newspaper to put under our feet to stand on so our feet wouldn't get so cold!

John - see my comment to Laurie and my post a couple of days ago.  In that post are two other links, to previous foam posts of mine.

With such foam, great care needs to be taken to bring fresh air into the HVAC systems.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Good Morning Jay.  Love the post!  Great job on the IR photos too! 

Happy Trails!!

Posted by Rob Smith (Rob Smith Property Investigations) over 8 years ago

Hi Jay, I had a post a while back about cellulose, Good post.

Clint McKie

Posted by Clint Mckie, Desert Sun Home, Comm. Inspection 1-575-706-5586 (Desert Sun Home, commercial Inspections) over 8 years ago

Happy Trails to you too Roy, um, I mean Rob!  And thanks!

Clint - I know we inspectors have posts that overlap, with our own twists.  But I write these and post them on other sites too.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay, my house was built in the late 70's and has cellulose. As it was insulated to older standards. I went in and covered this with batting...

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) over 8 years ago

So, Michael, how many inches of cellulose do you have - 4 or 5"?  Did you cover it with faced or unfaced?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay,

I much prefer blown insulation to batts.  In the 80's and 90's we did a lot with rock wool insulation blown into attics.  Good stuff.

What is your take on blown fiberglass, which is common around the Triangle?  Do you think the heat transfer in fiberglass is due to the material itself, or the poor sealing between batts and framing members?

Posted by Mike Jaquish, 919-880-2769 Cary, NC, Real Estate (Realty Arts) over 8 years ago

Mike - blown seems to need to be deeper to get the same R-value.  It traps air well and does fill holes better.

But I am with you - cellulose is a great product.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

I am a big fan of cellulose. One great characteristic is that dense packing it increases the R value and decreases air movement. Fiberglass can't say that.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 8 years ago

Yes Jim, I've heard that but don't know how it affects the R-value.  I tell people they can put a shelf over it too.  Packed it is very good stuff.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay, Pretty much the same as Michael, had cellulose as a base, went in and added unfaced fiberglass over top.  Certainly helped bring the heating bill down a bit :)

Posted by Liz and Bill Spear, RE/MAX Elite Warren County OH (Cincinnati/Dayton) (RE/MAX Elite 513.520.5305 www.LizTour.com) over 8 years ago

Bliz - any insulation on top of insulation will help a lot.  I teased someone the other day about putting dryer lint up there, but honestly I don't know the R-value!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay, over the years, I have added insulation to the attics of several of my homes. I want to ask you about your statement "If you add R15 to an existing R30 the result is R45." I have seen bats of fiberglass insulation collapse down to a 2" mat. Obviously in doing so it losses R value. This is the reason I've added a foot or two of cellulose on top of it. I'm sure the collapsed fiberglass still has some value but again I would assume it does not have it's intended value.

Posted by Bob "RealMan" Timm, Owner of Ward Co. Notary Services, retired Realtor (Ward County Notary Services) over 8 years ago

Bob - nice tie!  Fiberglass insulation (all insulation) traps air to act as a thermal barrier.  If fiberglass is crushed it really, really reduces its R-value.  R-30 crushed to 2x4" size by a plywood storage shelf might be reduced to as low as R-6.  Don't crush it!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay, yet another reason to recycle our newspapers!  I mean, who knew they could use it for insulation?  I have fiberglass that was blown into my attic back in the 1980's when I bought my house.  My cat decided to put her litter of kittens up there and I had to crawl under the eaves to find the little guys.  The cat probably crushed the fiberglass.  Hmmm.

Posted by Patricia Kennedy, Home in the Capital (RLAH Real Estate) over 8 years ago

Jay -- Thanks for the education. Those thermal pics are very interesting.  We use a lot of foam here in CT

Posted by Barbara Altieri, REALTOR-Fairfield County CT Homes/Condos For Sale (RealtyQuest/Kinard Realty Group, Fairfield and New Haven County CT Real Estate) over 8 years ago

Does this mean I need to start getting paper instead of plastic at the grocery store lol

We re insulated and then installed plywood flooring in the attic. Tighter all around

Still plenty of snow on the roof, evenly I might add

Enjoy the day

Posted by Don MacLean, Realtor-Homes for Sale- Easton Mass (New England Real Estate Center Inc.) over 8 years ago

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.)

Posted by John Mulkey, Housing Guru (TheHousingGuru.com) over 8 years ago

Thanks Jay for a very interesting and informative post!

Posted by Patrick Schorle, Patrick Schorle (Pacifica Real Estate Inc.) over 8 years ago

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.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 8 years ago

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

Posted by Virginia Gardner, Realtor, Charlottesville, Serving Central Virginia (Roy Wheeler Realty Co.) over 8 years ago

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. 

Posted by Suesan Jenifer Therriault, "Inspecting every purchase as if it were my own". (JTHIS-Professional Home Inspection Team) over 8 years ago

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

Posted by Damon Gettier, Broker/Owner ABRM, GRI, CDPE (Damon Gettier & Associates, REALTORS- Roanoke Va Short Sale Expert) over 8 years ago

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

Posted by Randy Ostrander, Real Estate Broker, Serving Big Rapids and West Central MI (Lake and Lodge Realty LLC ) over 8 years ago

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.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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...

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

Jay,

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

all the best...

Posted by Bill Saunders, Realtor®, www.BillSellsHotSprings.com (Meyers Realty) over 8 years ago

Thanks Bill for all your stopping by!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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.

Posted by Andrew Mooers | 207.532.6573, Northern Maine Real Estate-Aroostook County Broker (MOOERS REALTY) over 8 years ago

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

Posted by Barbara-Jo Roberts Berberi, MA, PSA, TRC - Greater Clearwater Florida Residential Real Estate Professional, Palm Harbor, Dunedin, Clearwater, Safety Harbor (Charles Rutenberg Realty) over 8 years ago

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

Posted by Angelia Garcia (Pure Realtors) over 8 years ago

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!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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" :)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 8 years ago

Good idea Reuben. 

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

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) over 8 years ago

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!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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