Attic Foil

Radiant Barrier FAQ's

Both sides of the foil look the same. Is there a top or bottom?

No, both sides are the same

What is the advantage of using a heavyweight radiant barrier foil?

Both the lightweight and the heavyweight radiant barrier foils have the same reflectivity quality. The difference is the lightweight products can tear easily. Generally foil comes in two weights: Lightweight which weights 13-16 lbs per 1000 square ft. or Heavyweight which weights 24-28 lbs per 1000 square ft. Atticfoil.com ONLY sells the heavyweight foil. The heavyweight foil is virtually tear-proof and will never rip or sag in your attic.

I hear some companies advertise savings up to 50% off your energy bill. Can this be true?

Probably not. Radiant Barrier is a great product, however the benefits are often over-sold. REALISTIC savings are probably in the 5%-25% range. Read: Do Radiant Barriers Really Work?

I keep reading you must have an air space or gap for radiant barrier to work. I still don’t understand why?

This is probably the most misunderstood requirement for a radiant barrier to work. Watch this video, hopefully, this will make it all clear.

I went to a presentation and they called the foil something else. Is this the same stuff?

It might be. To be totally honest, I sell to end users, and many professional installers. Some installers "Re-Label" or "Brand" the foil. The best way is to get a FREE SAMPLE and compare for yourself.

How can I determine how much foil I will need? Is there trick to measuring my home?

Read: How To Measure Your Roof For Radiant Barrier Foil

I see “Bubble Foil” in home improvement stores like Home Depot and Lowe’s - Is it better?

Bubble Foil is a good product and has many uses. The most common use is in metal buildings to prevent condensation. However, bubble foil insulation is often overused in residential attics. It does work, however it is the foil doing the work and not the bubbles in a ventilated attic. And, the bubble products cost a lot more. In addition, bubble foil products do not allow water vapor through often creating an unintended vapor barrier. Read about the difference between Bubble Foil, eShield, prodex and other products compared to Attic Foil.

Some Companies Sell "Laser-Perforated" Foil. Is there a difference?

This is interesting. I don't know of any company that MAKES laser perforated foil. But somehow it's in the market. I can't figure it out. It SOUNDS really high-tech and advanced, but here is the deal. We are talking about a bunch of little HOLES. Do you REALLY care how the holes are made?

Will Radiant Barrier AtticFoil Work With A Whole House Fan?

Yes, a whole house fan is basically just pushing air into the attic. You attic should have enough "holes" in it to allow the air to be pushed out of the attic. AttiFoil is not intented to be installed "airtight". If you install the foil so that the air being pushed into the attic still has a path to the "holes" it can still get out and the fan will work fine.

I have heard different views on whether it is better to staple to the bottom of the rafters or lay out over insulation. What is the best way to install radiant barrier.

It depends on several things. Whether you are in a Hot or Cold climate AND if you have ductwork inside the attic. And, whatever is the easiest. Read: What is The Best Radiant Barrier Install Method?

My attic is tricky. Is it OK to staple to the rafters on one part and lay out over the insulation in another part.

Yes, this will work fine. Remember, our main concern is to reflect the heat coming off the roof. It does not really matter where the reflector is or if they are mixed in placement.

What is the difference between Radiant Barrier Spray Paint and Radiant Barrier Foil. I hear the radiant barrier spray advertised a lot on the radio.

The differences are like comparing Apples to Oranges. They are VERY DIFFERENT products and the foil ALWAYS outperforms paint in reflectivity. Plus, installers can’t cheat when installing the foil. Read: Radiant Barrier Paint vs. Radiant Barrier Foil

Will Radiant Barrier still help if I can’t get it under my whole roof?

YES. Think of radiant barrier as shade for your home. The more the better. If you have a big tree over just part of your home it still helps right? Installing radiant barrier has a cumulative effect. Most people end up getting between 70-90% of their attic. Just install as much as you can as fast as you can and don’t kill yourself on the last little bit unless that’s just how you are.

Can I install Radiant Barrier between my shingles and my roof deck when I have a new roof installed?

NO! NO! NO! It WILL NOT work. You MUST have an air gap to have a radiant barrier.

Will dust accumulation affect the effectiveness of radiant barrier foil?

Usually this is not a problem. Read here for the full information on Dust Accumulation on Radiant Barrier.

Will Installing Radiant Barrier increase the temperature of my shingles and damage them?

The Department Of Energy has done testing and concluded that shingles temperature increase between 2º-10º degrees. Considering that on a hot Summer Day Shingles can exceed 170º this small increase in temperature should have a minimal affect (if any) on shingle life.

Should I install 2 layers of Radiant Barrier? I’m thinking of about stapling to the rafters AND laying out over the insulation.

Two layers are not necessarly better than one. The FIRST layer will reflect 97% of the radiant heat, so the second layer is only effective on the small amount that gets through. Considering the extra time and money, it’s probably not worth it.

If I lay foil over my ducts, will this help?

If you already have silver flex ducts, you already have a radiant barrier on your ductwork. An additional layer will not have much of an effect. If you have black, or grey ductwork foil over the ductwork will help reduce radiant heat gain into the ducts.

How far down the roof slope should I put the foil. Will I block airflow from the soffits?

It’s almost impossible to block airflow from the soffits. In normal construction, the soffits are about 12” below the top of the wall plate. And, by stapling to the bottom of the rafters, you will always have an air passage the size of the rafters.

My roof has hips and valleys, how do I Install in these parts?

Pretty much the same as the rest of the attic. Just leave a gap, slit or othere method for air to travel behind the foil. See Open-Ridge Installation instructions for more info.

Should I tape the seams?

Not unless you really want to. It does not help/hurt the effectiveness of the foil and only makes the foil look “prettier”. Plus, since there is really nothing to press the tape on to, taping the seams is more difficult than you think.

Is this the same stuff that was developed by NASA?

NASA did develop Radiant Barrier Technology. It has been a public domain technology since the 1970’s. Radiant Barrier Technology is used in thousands of products like candy wrappers, potato chip bags, oil rig fire fighting suits, thermos bottles and emergency fire shelters and construction and insulation materials. Yes, NASA technology is used in all Radiant Barriers, but this is not the ACTUAL stuff used by NASA.

Wouldn’t the foil be more effective if I cut it and put it BETWEEN the rafters directly on the bottom of the roof deck and not across the bottom of the rafters?

No, If you cut the foil and put it between the rafters, you will still allow thermal bypass through the rafters. Heat will pass through the rafters and will re-radiant below the foil decreasing the overall effectiveness of the foil. When you staple the foil BELOW the rafters it will eliminate the rafters from emitting heat as well as reflecting heat from the deck. Plus, it is a lot easier to install to the bottom of the rafters since you do not need to cut the foil or deal with thousands of nails sticking through. Bottom line is that it is MORE work to get LESS benefit. Bad choice.

What size staples do I use?

1⁄4” or 5/16” is all you need. Figure about 500 staples for every 1000 square ft. of foil installed.

Will it affect my attic-mounted antenna?

Maybe. The best way is to install as normal. If there is a problem with reception, remove a small section of foil over the antenna. This will usually fix any problems with TV Reception.

Will it affect my cell phone reception?

Usually it won't. An easy way to test is to get a FREE SAMPLE. Cover your cell phone with the radiant barrier foil and call it. If it rings, then the phone should work find after installing foil insulation in your attic.

How Can I Install Radiant Barrier Foil in a Cathedral Ceiling.

A typical cathedral ceiling is shingles, roof deck, insulation, sheetrock. In order to put a radiant barrier, you will need to get a layer of foil AND an air gap on one side of the foil. This video explains how to install radiant barrier in a cathedral ceiling

Do Energy Savings Improvments REALLY Payoff.

This video explains how spending money on making your home more energy efficnet results in a GREAT return on investment.

I've read all the information, and it doesn't look TOO hard to install myself. Truthfully, how HARD is it really to install?

You CAN do it. If you do regular do-it-yourself projects then you are probably capable. I'm not going to lie to you. Some attics are EASY compared others. How "crowded" or "tight" your attic tends to be a biggest factor to make the job "hard" even more so than installing in the heat of the Summer. The thing to remember is that it's your attic. You can do a "bad" looking job and it sill works fine.

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