Asked on Feb 3, 2012

I covered my attic insulation with an aluminum double layered sheets.

LeeAnn GerlemanWoodbridge Environmental Tiptophouse.comMelissa Gutilla


Haven't had time to see effect on electric bill, but we seem to hold in the heat much better. Anyone else tried this. The biggest change will be when the heat of summer gets trapped in the attic instead of fighting the air conditioning.
13 answers
  • KMS Woodworks
    on Feb 3, 2012

    These "foil" installs are more about reducing summer gains than keeping winter heat in.

  • 3po3
    on Feb 6, 2012

    I would also be curious to see if this helped with winter heating bills. I have always assumed the foil barriers are purely for blocking summer heat, as KMS said.

  • I would be interested in knowing just how well this works and what product it was that you used. Many of these products do not allow for proper ventilation and end up causing moisture and mold issues. Keep us posted and keep an eye on the attic for condensation to form.

  • I hope you made consideration for venting moisture out and not trapping it under the sheet or you will ruin the insulation under it with mold

  • Nichter, that is exactly my point. Many of these foil barriers do not have the ability to properly transfer moisture and many more although claim to have micro holes to allow for this transfer to take place. The holes are simply way to small and end up getting plugged by dust. Which all attics suffer from.

  • Peter C
    on Feb 7, 2012

    I didn't know of the problem, but the attic is loosely laid and even goes over aid ducts. I also have vents at both ends and a fan when temps get too warm. I will check on it though as time passes. It is too soon to see if it lower bill as we have had a very mild winter.. But if I crank up the heat or the fireplace for a few minutes I can tell the heat lasts and is not going out through the attic. I also had it put in the ceiling of my unfinished work room which is under the living room. I can tell it holds back the chill that used to seep up from that unheated room. Has the EPA made the light tower there in Edison switch to the screwy bulb?

  • Reflective insulation only works when there is at least a one inch air space in front of it. Since you have this laid directly on top of the current insulation, that condition does not exist, so if you are noticing a difference in comfort level, that indicates to me that your gain is in that this sheet material is slowing air currents of infiltration/exfiltration - in other words, you have air leakage from the house into the attic, and if this is slowing that, it is also trapping any moisture from the house that moves with that escaping air. Trapping it in the insulation means you will soon have mold growing. I have had to repair a few of his sort thing, and it is neither fun, nor cheap The proper use of this type film is to staple it to the bottom of the roof rafters to act as a reflective barrier without interfering with ventilation. Best example I can think of the demonstrate the problem - wrap yourself up in a plastic wrap or bag. At first, you will feel warmer because you have blocked drafts. Shortly tho, as moisture builds up, you will feel more and more uncomfortable. You wil experience swings of hot and cold because you have interfered with your body's temperature regulation systems. Then after more time, you will notice other negative effects if you left that bag in place for long. Bacteria and fungii would find a happy home on your skin, just as they will in a damp attic.

  • Peter, the condensation will form under the foil not on top. Your home creates a natural drafting effect. Meaning air that is entering into the basement along the sill area is being pulled up through the wall cavities in the spaces between the wall board, pipes, wires and air duct openings. When this happens it pulls the natural and man made moisture with it. When this ends up into the attic it naturally vents out through the gable, ridge and roof vent systems. In the average home we can see this many times per hour where the entire homes air volume is exchanged which results in very high energy bills. The reason for the vapor barrier that is installed with the insulation is to slow down this movement that occurs as far away from air temps that would cause this moisture to condense. When the vapor barrier is damaged, or it leaks or is simply not there the moisture will continue to move until it is either changed back to water, freezes or condenses on some surface that is cold enough to do so. Much like the glass of ice tea in summer. You see the outside of the glass get wet. Same thing happens in homes. This is why the vapor barrier is so critical. Well we have learned as building scientists that the vapor barrier is being bypassed all the time. We see this as condensation that forms in the attic and turns the back of the roof black. We hear about it when people complain of dry skin in winter, and we see it in our pocket book when we get our utility bill. What this foil barrier ends up doing if you have these leaks, And most do unless your a high end energy star built home. That the moisture moves into the space between the foil and the living area and condenses against the cooler side. The result is moisture that ends up dripping down onto the insulation below. The very stuff that this is in effect trying to help. The result then is lower R value as the moisture allows the heat to move through the insulation faster. Also your cooling and or heating system is located in effect a unconditioned space. This very fact causes the sizing load of the system to increase almost 20% more then it would have if the system was located inside the house such as the basement. So in effect the foil barrier has assisted in trapping heat that has been going out of the home helping much like a blanket helps keep us warm on cold nights. So the decision to keep, fix or remove the barrier is a difficult one to make. In some ways it does help, but still in others it can cause health issues as the moisture that will be trapped in the attic will condense and feed any possible mold that may be present. Keep an eye on this and watch for any signs of blacking insulation, wood or stains. This will happen over time and not over night. Edison Light? Do not say that to loud. This may give one of those nut jobs something else to screw up.

  • Once he sees the signs of blackening molds it is too late. I know of one family whose young son was very adversely effected by mold in the house. When I inspected it, I found a film on top of the attic insulation like this and very wet moldy FG insulation, especially in the area over the bathroom, kitchen, and unfortunately, the child's bedroom, all of which were on the north wall and where the parents had been regularly running a moisturizer/humidifier to 'help' with all his symptoms. They were unknowingly feeding the mold that was causing his health problems. A good book on this subject for homeowners is "Help, My House is Killing me"

  • That is a great book Nichter, I know the author very well. I used to hand out that book with every home mold job that my company did. The only thing I can add is to stand back after reading it to try to understand what he is saying. If you take everything he says and act upon it, you would never even build in a basement. But if you understand the theory of what he is saying, your will build and live much smarter. And understand why things happen when you try to cut corners when finishing a basement etc.

  • Melissa Gutilla
    on Dec 6, 2012

    I can tell everyone from personal experience Mold is horrible if you have allergies!! We lived in a home about 10 years ago that got very little light because of the trees in the yard. Our yard was mainly moss and the back of the house had to be cleaned every other month with bleach water because of mildew. My allergies got so bad that I was sick all the time. My lymph nodes swelled up to the size of quarters. Within a month after moving I was not sick and my lymph nodes were almost back to normal size. When you are sick all the time with no energy and a general overall fatigue that will not go away PLEASE INSPECT YOUR HOME!!

  • Melissa all great points. Mold can be difficult to detect and can cause all sorts of strange illnesses that people would never even think was being caused by a mold issue.

  • LeeAnn Gerleman
    on Jul 10, 2015

    You're in a different climate than I am, in Iowa. but as soon as I moved into my house, I did to my house what my Dad always did. I put a larger screened in grate on one side of the attic, and on the other side, I put a fan with a humidistat which opens the shutter to force hot humid air out of my attic. It works like a charm. In real hot weather, it can drop the heat in the house by ten degrees. You have to be careful if you don't have enough ventilation, it can draw from the house, and could pull out carbon monoxide. So you need a large enough area of ventilation. But when it gets hot outside, my shutters open, it blows hot air out of the attic, then closes. Its worked like a charm for over 10 years now, and my electric bill dropped about 40 dollars a month.

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