anyone use radiant guard foil insulation?

[Mike Gager]

im insulating my gargae and putting R13 in the walls and trying to decide what to do about the roof. i am considering using the reflective foil inslution sold by several companies installing it directly to my roof rafters. this would by far be the easiest for me to do. they claim it will work very well on its own but im still a bit skeptical. wondering if anyone has used it before and what they think?

[David G Baker]

I have been thinking about doing the same thing but using it on the walls of one of my out buildings instead of fiberglass. I do have the foil covered bubble insulation on my pole barn roll up door. It does help but on a hot day with the Sun shinning on the dark brown door that is looking directly South I wonder just how good it is because the foil on the inside of the door is very warm.

[Pat Germain]

If you're talking about the stuff which is just a layer of foil, it's pretty much worthless. It's just a bunch of hype.

This isn't just my opinion. I used to see contractors pushing that stuff a lot when I lived in Virginia. They claimed it would keep a house significantly cooler in the summer. (Southern Virginia gets very hot.)

I did some research. Every single source afilliated with installers gave the foil insulation glowing reviews. Every single source not affilliated with installers said it was worthless. Consumer Reports said if installed exactly as the manufacturer recommends, which almost never happens, the foil insulation had some effect, but it was negligable. Since the stuff was typically not installed as it should be, it typically had no effect whatsoever; other than emptying a homeowner's wallet.

If you're talking about actual insulation which has a foil backing, that's another story.

[Mike Gager]

pat, i am talking about the thin foil insulation thats about 5-7mm thick

i have done quite a bit of research and i havent found any negative reviews about the stuff, i would be much apprieciative if you could link me to some you have found

its also curious to note that the IRS offers a tax credit for people who install the radiant barrier in their house

[Mike Gager]

here is what the US department of energy says about it, if anyone is interested. i have highlighted a couple key points in red

to add to davids post the reason the foil feels hot on your garage door is explained in the 1st 2 paragraphs

http://apps1.eere.energy.gov/consume.../mytopic=11680

Radiant Barriers

Radiant barriers are installed in homes—most commonly in attics—to reduce summer heat gain and winter heat loss, which helps lower heating and cooling costs. The barriers consist of a highly reflective material that reflects radiant heat rather than absorbing it. They don't, however, reduce heat conduction like thermal insulation materials.
How They Work

Heat travels from a warm area to a cool area by a combination of conduction, convection, and radiation. Heat flows by conduction from a hotter material to a colder material when the two materials touch. Heat transfer by convection occurs when a liquid or gas is heated, becomes less dense, and rises. Radiant heat travels in a straight line away from the hot surface and heats anything solid as the wave of energy hits it.
When the sun heats a roof, it's primarily the sun's radiant energy that makes the roof hot. A large portion of this heat travels by conduction through the roofing materials to the attic side of the roof. The hot roof material then radiates its gained heat energy into the cooler attic (some of the roof's heat will radiate in other directions too). A radiant barrier reduces the radiant heat transfer from the roof to the attic space.


A radiant barrier's performance is determined by three factors:

• Emissivity (or emittance) – the ratio of the radiant energy (heat) leaving (being emitted by) a surface to that of a black body at the same temperature and with the same area. It's expressed as a number a between 0 and 1. The higher the number, the greater the emitted radiation.
• Reflectivity (or reflectance) – a measure of how much radiant heat is reflected by a material. It's also expressed as a number between 0 and 1 (sometimes, it is given as a percentage between 0 and 100%). The higher the number, the greater the reflectivity.
• The angle the heat wave strikes the surface—a right angle (perpendicular) usually works best.

All radiant barriers must have a low emittance (0.1 or less) and high reflectance (0.9 or more). Of these factors, the angle the heat wave strikes the surface has the most influence on how well any shiny surface acts as a thermal insulator. From one brand of radiant barrier to another, the reflectivity and emissivity are usually so similar that it makes little difference as far as thermal performance. (Most products have emissivities of 0.03–0.05, which is the same as a reflectivity of 97%–95%.) Also, the greater the temperature difference between the sides of the radiant barrier material, the greater the benefits a radiant barrier can offer.
Radiant barriers are more effective in hot climates than in cool climates. Some studies show that radiant barriers can lower cooling costs between 5%–10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. But in cool climates, it's usually more cost effective to install more than the minimum recommended level of insulation rather than a radiant barrier.

Types of Radiant Barriers

Radiant barriers come in a variety of forms, including reflective foil, reflective paint coatings, reflective metal roof shingles, reflective laminated roof sheathing, and even reflective chips, which can be mixed with loose-fill insulation. The reflective material, usually aluminum, is applied to one or both sides of a number of substrate materials. Substrate materials include kraft paper, plastic films, cardboard, plywood sheathing, and air infiltration barrier material. Some products are fiber reinforced to increase the durability and ease of handling.
Also, radiant barriers—which don't provide a significant amount of thermal insulation—can be combined with many types of insulation materials. These combinations are called reflective insulation systems. In these combinations, radiant barriers can also act as the insulation's facing material.
Installation

Radiant barriers can be installed between the roof sheathing and attic floor insulation, in cavity walls, and around door openings, water heaters, and pipes. It's easier to incorporate radiant barriers into a new home, but you can install them in an existing home too.
An installer typically drapes a rolled-foil radiant barrier foil-face down between the roof rafters to minimize dust accumulation on the reflective faces (double-faced radiant barriers are available). This is generally done just before the roof sheathing goes on if it's not too windy, but it can also be done afterwards from inside the attic by stapling it to the bottom of the rafters.
When installing a foil-type barrier, it's important to allow the material to "droop" between the attachment points to make at least a 1.0 inch (2.5 cm) air space between it and the bottom of the roof. This air space has mainly two functions: it creates an air channel for the soffit and ridge ventilation system to work more effectively, and it acts as a second reflector since there are two shiny sides (one facing up/ one facing down.)
Some builders also try to attach the radiant barrier directly onto the roof sheathing prior to their installation on the roof rafters. However, a more effective method is to simply buy foil-faced plywood sheathing instead. There are also metal roof shingles that have a reflective underside. If you need roof shingles, these are a practical option, but the cost of this type of radiant barrier is considerably higher than other types.
A radiant barrier installed on top of attic floor insulation is more susceptible to dust accumulation. This undesirable installation method may also trap moisture in fiber insulation during cold weather. A radiant barrier installed on the cold side of the insulation acts as a vapor barrier in the wrong location. When warm moisture carrying house air leaks into the attic in the winter, it may condense on the underside of the barrier. Even a perforated radiant barrier can trap moisture in cold climates since the water can freeze in the small holes and seal them. Because of these hazards, it's strongly recommended that you NOT apply radiant barriers directly on top of the attic floor insulation. Of course, installing them at all in a cold climate is not generally cost effective anyway.
A radiant barrier's effectiveness depends on proper installation. Therefore, it's best to have a certified installer do it.
If you want to install a radiant barrier yourself, obtain instructions and safety precautions from the manufacturer. Carefully study and follow these directions. You should also check your local building and fire codes.

[Pat Germain]

As I recall, the article Mike posted is very similar to what I read in Consumer Reports years ago. Sorry, I don't know specifically which issue it was.

I would think for anyone considering installing foil insulation, an online membership to Consumer Reports would be well worthwhile. As I understand it, you can access article archives on the CR web site.

I'm thinking the tax credit has a lot more to do with industry lobbying than with actual effectiveness of the product.

I'm also thinking the foil insulation is a lot like fuel saving devices for cars. You can find all kinds of personal testimony saying they work, but physics says otherwise. The personal testimonies tend to be positive because people want it to work.

In a car, people drive conservatively after the device is installed and, surprise, mileage improves. With the insulation, it's likely people pay to have it installed and they're very careful about keeping windows and doors shut and regulating the thermostat. Surprise, their utility bills go down.

[Larry Edgerton]

Mike, I am not sure what your climate is like but here we have huge swings in temp and humidity, and I refuse to use a vapor barrier type of material on the ceiling for moisture reasons. Does your garage have conventional ceilings/trusses? What is the ceiling height?

The reason I ask is that in the house that I am living in I tried an experiment that I always wanted to try but no one would pay for. simply, I drywalled the ceiling twice with an airspace in between. the first layer has been carefully taped but not finished, then 3/4 select poplar strips across the ceiling joist, and then the final layer of drywall, finished normally. I also built a soffit around the rooms 8" wide and 6" tall to add detail and give me a chase I needed so as not to have to compromise the insulation in the walls any more than necessary with wiring and a place to run my infloor heat runs. This is lined with 1" thermax at the ceiling and outside wall, any tiny gaps are hit with a foam gun. This insulates the weakest point, where the ceiling meets the walls and insures that no framing has a direct connection to the finish drywall. Any ceiling fixtures are totally sealed despite the complaining of the electrician.

I have no ventilation at all, and only 6" of insulation in the attic, in fact the tops of the joist are still showing, and yet I am the last house on the street with snow on the roof, and I never have an icicle one. I have 1000 sq ft, and I keep it warm, and my heat/hot water bills are under $100 in the dead of winter. Hot water alone is $50 in the summer so I am heating my house with natural gas for $50 and I am 60 miles above the 45th parallel, in other words it gets cold here.

I actually meant to insulate the attic with a foot of blow in but the payoff is just not there, but I should do it to be kind to the earth. Next year....

This is cheap and effective if it will work for you, if you have any questions PM me and I will call you.

Another note. Do not take any Government studys as gospel, they are full of bull about 50% of the time and their studys are tainted by industry "experts" that are nothing short of lobbiests. For example in the sixtys the advised that you switch to electric heat, insulate the floors, and cover the bottom of the joists with plastic. In the 70's a good portion of our work was fixing floors that people fell through because the floors are rotten. Now they are forcing us through code to use Tyvek on all walls and go around windows with Bitutane, a mistake that I have already seen the results of in the short time the code has been in place. Walls are rotten and window flanges are rusting and windows falling out of homes less than ten years old. These are codes put on us by lobbiests, not for the betterment of homes.

Morning rant over....

[Ed Moehlenpah]

The building inspector - who btw doesn't get anything out of this - recommended using radiant barrier OSB on the roof (underneath the shingles). It seems to really help on hot days here. This was for a 24x24 garage shop with trusses. I'm glad I spent the extra $1-200 bucks.

[M. A. Espinoza]

im insulating my gargae and putting R13 in the walls and trying to decide what to do about the roof. i am considering using the reflective foil inslution sold by several companies installing it directly to my roof rafters. this would by far be the easiest for me to do. they claim it will work very well on its own but im still a bit skeptical. wondering if anyone has used it before and what they think?

Hey Topeka, how is Kansas? Moved to Hawaii about six months ago from Lawrence.

A lot I have to offer is anecdotal since I have not installed a radiant barrier.

I don't know how much you would gain from radiant barrier in Kansas. The summer sun is pretty strong but standard glass does pretty well, however there is something to be gained from a radiant barrier.

In Hawaii I can't believe that a lot of these houses are uninsulated single wall construction. I mention insulation and people laugh and ask if I'm cold. (but its relative, the TV weather had a graphic that said "chilly" conditions, it was predicted to be 64 degrees night-time low)

In summer "hot" here is 85 degrees but it can be 95 in these uninsulated houses due to the intense sun down this low in latitude. The eastern walls will be hot to the touch by 8 in the morning in the summer. If you are standing near these walls its the same effect as a radiant panel heater. Placed some sheets of plywood between the wall and me and the effect was immediate.

But this is Hawaii and the sun is really intense. Any heat you can keep out of the structure in the first place will only help. If you do use it just make sure your ventilation can handle it otherwise you will be making a solar oven and cook your roof.

[Mike Gager]

well you know how kansas is, 50 one day 5 the next and then 50 again the day after that haha

[Nick Semon]

I was researching foil insulation and this thread came up which surprised me because it is so old. Maybe I can help clear up some issues for future readers. To comment on Mike’s original question. If you are putting R13 in the walls, why aren’t you putting it in the ceiling as well? You might be and I misunderstood. If you are not you will be severely limited. By using fiberglass insulation, you are creating a blanket of material that stops air movement and slows conductive/convective heat transfer but are leaving out the top, ironically where most heat will rise to. It’s like having a blanket on your sides and not on top of you.
Regarding foil insulation it does work and anyone who tells you it doesn’t is just flat wrong. Nor is it helpful to copy generalized information is not specific enough to quantify. To comment on a few points. You can’t just say something is worthless and not explain why it doesn’t work. Let me start by saving this, if you take a standard sheet like radiant barrier and sandwich it between two layers of sheathing on a floor for instance it will not do anything to help. You would have wasted your money. However if you take the bubble foil insulation and do the same thing you would achieve an R rating on 1.1, pretty dismal. You wouldn’t even have the effectiveness of radiant barrier at this point the entire reason you bought the product.
However, if you take these same materials and use them correctly in attics, pole barns, metal buildings, as duct wrap insulation and follow proper installation procedures accounting for an airspace you will get the results these products claim. But, you need to look further into your specific application and understand your building, your climate, and what you are trying to accomplish by insulating.
I’ll bet you a roll of insulation if we are in a pole barn in Tennessee for instance and the overhead sun is beating down in June I’m going to me much more comfortable and cooler in my barn insulated with reflective insulation than yours without.
Let’s take a Northern climate example. I’ll bet when it’s -10F outside in New Hampshire and your HVAC system is heating your house with trunk lines running through your basement, attic, or crawlspace my house is much more efficient than yours at delivering heat if my ducts are wrapped properly in reflective insulation. Or the same example would be my camper’s air conditioning system works much better than yours in Florida because my HVAC lines are wrapped in reflective insulation.
Saying reflective insulation does not work means that every potato chip bag would disappear, and all the packaging material being used would no longer contain reflective material. We might as well take the reflective lining out of coolers too. Reflective technology is truly everywhere and its products are used in the construction process of most major industries. Just like an engine needs to be correctly installed in a car to make the car work so does insulation in buildings. Even the fiberglass company’s product is worthless lying on the ground. It has no R value until it is installed in a wall cavity, at a specific depth to achieve the R rating it claims.
Regarding industry lobbying, the fiberglass companies have the lobbyists, not the reflective companies. They have big ones too, in Washington. Do you ever wonder why fiberglass insulation is building code for new construction in all 48 states and no other products are? Is it because fiberglass is so good and all products are not equal. Look at the thermal benefits to using spray foam over fiberglass and building codes should change overnight. It’s unfair to comment about products in a general way without drilling down into the specific project being worked on and offering products and solutions that help.
With that said, Mike I think if you have not already installed the R13 in your ceiling I would do that especially if you are heating the building and have a cold winter climate. If you live in the south and just want it cool, take the insulation out and use it for something better, maybe extra in your house. Install reflective insulation. Or if you heat in the winter, install reflective insulation and maybe fiberglass. It all depends on your climate, your building, and your intentions. None of these are clearly listed in this post therefore accurate recommendations cannot be given. I’d like to see you use reflective insulation and if you are willing to give it a try I would be willing to give you the best deal anywhere, maybe even free if you are willing to install it and post an honest review of the material so we can all see what you think of its effectiveness in your building when it is installed correctly. Only then can we counterattack the negative hype. We’d love to speak with you. Let us know if you are interested. www.insulationstop.com Thanks for the time. We’d love to hear your opinion. After all, that’s the true meaning of a forum.

[Jim Andrew]

I've attended meetings to promote the use of insulation and other products when I was in the building business, and one thing pointed out was that a layer of foil equals one R factor. Whether it is a layer on the back of sheetrock, or a layer on foam board, or just a foil vapor barrier, it is one R factor. Also, have had guys say what great results they had with insulating the rafters and also the ceiling of a building. They said they could keep a lot of the roof heat from getting into the attic, and by also insulating the ceiling kept the attic heat out of the building. My opinion is that if they stacked all the insulation on the ceiling they would achive about the same thing. Main thing I learned is that for the good it does, insulation is the cheapest material used in building a building, as it saves the most on your heating and cooling bill.

[Rick Potter]

I have the roll of bare foil stapled to the rafters in my garage. I have no empirical proof, but it didn't seem to make any difference at all to me.

I also have the OSB with foil backing on the new addition to the house. Even before we put the insulation in the attic, we could tell the difference. When the inspector came to check it, he told us that the OSB/foil sheeting would make a 15 degree difference in the attic. I wish I had it in the rest of the house.

PLEASE NOTE: The OSB/foil roof sheeting is installed with the foil DOWN, not up.

[Gene E Miller]

Greetings & Salutations, I have a 30 x 50 metal building that I have my shop in and before I framed off the shop section and insulated it I installed the radiant foil against the rafters of my building. I have one 5' section that I have yet to do because of not being able to get my scaffold in that area and on a hot day you can stand in that section and then move to where it is installed and feel the heat difference. I also put a temp gauge to use and found that there was at least a 10 degree difference and sometimes as much as 15. So imho I would say it was worth the money. When I framed in my shop section and installed insulation in all the walls even in the outer part where I have no heat or air there is even more of a noticeable difference. I also put 12 inches of blown insulation in the roof section over my shop so where I do my most work stays very cool with a thru the wall installed AC and in the winter I use a ceramic propane wall heater for heat and very rarely have to have more than one section on to be more than comfortable.

[Thomas Bank]

The first thing to remember about the foil radiant barriers is that they need somewhere to radiate heat to - a system to carry the heat away. First, if you stick a piece of foil between (in contact with) two sheets of plywood (or any other material), you aren't going to have any radiant heat - you'll only have conduction - and a radiant barrier isn't going to do anything about conductive heat. Second, if you have an enclosed air space with no way to vent it, the heat builds up in convection and you're back to conduction.

So you need a vented airspace. For my workshop, I started basic rafters and roof sheathing with eave and ridge vents. I put foil coated rigid insulation in such that there was a 1/2" airspace between the roof sheathing and the rigid insulation. Caulked the edges of the rigid so that there was no air infiltration past it. Then batt insulation and drywall with the vapor barrier of the batt against the backside of the drywall.

The sun warms up the shingles (radiation) which warms up the sheathing (conduction), but then is stopped by the airspace. The heat from the sheathing radiates across the airspace, but the foil barrier stops this and keeps the heat in the airspace. The air flowing from the eaves to the ridge through the airspace carries this heat away (convection).

I'm one of those "it may work well on paper, but how does it work in real life" sort of people. I was pretty amazed at how much cooler this system keeps the second floor of my shop. It was an experiment on my part, but it definitely passed the test.

Back to the foil bubble wrap. First, yes it can be a radiant barrier when used properly. But, no, it is not the miracle insulation some people would have you believe. Do you really think that an 1/8" of plastic bubbles is going to give you some miraculous R-value when any other material is going to require inches of material to provide a decent R-value?