Reuben's Home Inspection Blog

A Warning About Radiant Barriers – aka Foil Insulation

March 6th, 2012 | 12 comments

Radiant Barrier InsulationLast week I received an email from a concerned reader who said his 85-year-old mother-in-law had recently purchased a $2,500 radiant barrier insulation system for her 1,800 sf townhouse in Austin, MN.   She was convinced that this was a good investment after attending a free dinner, wherein the effectiveness of radiant barriers in Minnesota was highly exaggerated.  The system was installed two days after she signed the contract.

Radiant barriers are essentially bubble wrap covered with foil on both sides.  The material is sold in rolls, and is quite easy to install.  The problem with this product is that it only works to prevent radiant heat transfer; it does nothing to prevent convective heat transfer, conductive heat transfer, or air leakage in attics.  Can you guess how much heat is lost in Minnesota attics due to radiation?  I’m no engineer, so I can’t give you any hard numbers… but I know the answer is very close to nothing.  In other words, the value of a radiant barrier in a Minnesota attic is very close to nothing.

I immediately wrote this concerned reader back, telling him this system was a waste of money.  Two days after that email exchange, the Minnesota Department of Commerce issued a consumer alert warning about these types of insulation systems, saying the exact same thing.  They’re a waste of money.

Oak Ridge National Laboratory has concluded that radiant barriers will give an average Minnesota home some savings in energy – somewhere around $10 – $40 per year, assuming the home has ductwork in the attic.  The problem with applying this generous savings model to Minnesota homes is that most Minnesota homes don’t have ductwork in the attic.  With no ductwork in the attic, the average annual savings would drop to about $5 per year.

If you want to improve the insulation in your attic, hire a reputable insulation contractor from Minnesota.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Home Inspector

        

12 responses to “A Warning About Radiant Barriers – aka Foil Insulation”

  1. clyde cameron
    March 6, 2012, 7:22 am

    she’s might have a legal leg if her relative wants to pursue it. There’s supposed to be a 3 day “let me think about it” period I believe. My dad got clipped out of a few hundred k by people like this when his brain turned to mush. The scammers are more than likely out of the area by now. Time to take over Moms finances for her, and count this as a 2500 learning experience… it’ll probably happen again.

  2. Fred Murtz
    April 3, 2012, 10:56 am

    “She was convinced that this was a good investment after attending a free dinner,…” That was an expensive free dinner.
    What a scam…invite a load of lonely, fixed income seniors to a free dinner and scam them into expensive needless home improvements.

  3. David Beustring
    October 17, 2012, 9:46 pm

    I am looking at buying a fifth wheel RV that has foil insulation in the roof and floor. They say its the same as having R40 insulation. Any help here?? Sounds good, but————————– Dave in Mountain Home, AR. Will be looking for a return.

  4. Reuben Saltzman
    October 18, 2012, 3:35 am

    David – it’s not at all the same as having R40. What kind of help are you looking for?

  5. Fred Murtz
    October 18, 2012, 11:39 am

    What is the practical application of radiant barriers?
    If one is in a hot climate and has A/C ducting in an attic, would one wrap the duct work with the radiant barrier to prevent/reduce the duct work from warming due to attic heat?
    In other applications, I see people who have the foil barrier inside their car to block the sun/reduce the heat in a car…Is this application doing anything other than stopping the dashboard from being exposed to the sun..would a piece of cardboard do the same?

  6. David Beustring
    October 18, 2012, 10:53 pm

    The fifth wheel were looking at is a Denali, made by Dutchmen. They do say that residential fiberglass insulation, plus radiant foil insulation is used in the roof. They call it a R40 insulation Rating. How thick would the roof on a fifth wheel have to be to have that rating? Also the floor—front— & gooseneck has an R40 rating—-

  7. Reuben Saltzman
    October 19, 2012, 3:47 am

    Fred – I don’t think there is any great practical application for a radiant barrier. I’m guessing cardboard would work just about as well as foil on a vehicle dashboard… I might have to do a little experiment with this next summer.

    David – a 12″ batt of fiberglass insulation will give an insulation value of R-38. Maybe they threw a radiant barrier on top, and they’re calling it R-2?

  8. Kris
    January 1, 2013, 4:01 pm

    My father had me sit in on a sales call by a tradesman selling “radiant insulation” in the Omaha area. Since my dad is on a fixed budget and I am an engineering student, he likes to run these things by me.
    The very unrealistic demonstration using a heat lamp to “simulate” attic conditions really upset me, and the salesman was quickly removed from the house.
    My question though is this:
    We heat primarily with a wood stove during the winter. The wood stove is located in a room with a lot of south-facing glazing.
    The south windows are great on sunny winter days, but not so much during the night or on overcast winter days. Even though we splurged and bought triple-pane, the glazing is always going to be a weak link in the insulation.
    So I am considering buying a ceiling-mounted curtain track and some kind of mylar curtain to be used during the night and on overcast days to help keep the heat from the wood stove from radiating out of the house. There’s roughly 56 square feet of glazing there.

    Will this be a practical application of a radiant barrier?

    We already have 70% of the house insulated with closed-cell foam–haven’t got to tearing out the drywall to replace the rest of the fiberglass yet.

  9. Reuben Saltzman
    January 2, 2013, 5:43 am

    Hi Kris,

    I think you would be better off asking a fellow engineer / engineering student; your idea makes sense to me, but I might just be overlooking some basic flaw with this concept.

  10. Tim Dunning
    September 15, 2013, 11:35 am

    Reuben.

    I appreciate your comments on this topic however I don’t see any hard facts in your article. It would be great if you could include some facts. I am considering installing a radiant barrier in my home and the people selling the product provide facts and government studies showing the benefits.

    Kind Regards.

  11. Reuben Saltzman
    September 15, 2013, 12:05 pm

    Hi Tim,

    I gave a link to a government warning basically telling folks that these things are a waste of money, as well as a link to the information page at ORNL on radiant barriers. What info are you looking for?

    – Reuben

  12. Kris
    October 17, 2013, 3:27 pm

    I went ahead and bought a roll of that radiant insulation to use in selected areas around our house, but the main reason for my comment today is that I attended one of those sales dinners where they try to scam you on the stuff.
    The sales rep made incredible, unverifiable, and patently false claims about the R-value and energy savings of the stuff, ignored convective and conductive heat loss, and ignored the fact that most of the energy in a house is lost through the doors and glazing.
    I am busily submitting complaints to the BBB, the DOE, the FTC, and anyone else that I can think of.
    Radiant insulation does have value in specific applications, but in climates that experience cold winters it won’t pay off.

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