RADIANT BARRIER ATTIC GUARD FOIL:Is it worth it?

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68sting

Active Member
I need to blow some insulation in my attic after I beat it all down running wires. I was at a local home show a few weeks ago and there were numerous booths offering this radiant barrier. I can pick some up on eBay(220202462804) and wondered if this would be a wise investment of my time and money before I blow more insulation in. Let me know what you think.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...A:IT&ih=012

Thanks
Lance
 
I installed it in my house . . was recommended by the company that I bought my radiant heat tube from . . I have it in all ceilings (and under the 1st floor slabs). . first floor ceiling is to help keep the heat from the tubes in the second floor from heating the space below . .

with todays heating/cooling costs (and thinking about what tomorrows will be) it can't hurt . .

. . you can also use foil backed fiberglass for the same effect . .

Pete C
 
As someone with HVAC in the attic, I looked at this as a way of reducing the summer heat in the attic. The problem is I have a HUGE roof and doing all of it would be both expensive and very time consuming. I also thought about getting some of the spray foam insulation in the rafters, but I read that this can cause the roof to be hotter and reduce shingle life.

So for now my solution is going to be, and I need to do it sooner than later, is to insulate the ductwork and see if that helps the system cool.
 
I have a house that has an addition over the Garage and thus 2 different roofs/attics. The one with shade from the trees has no radiant barrier the one directly in the sun has a radiant barrier against the roof (not the floor of the attic). The one with a radiant barrier is noticeably cooler in the summer. My homeseer and DS18S20 show that the radiant barrier attic is normally 10-20 degrees cooler. For me the 10-20 degrees cooler was worth it.
 
While I cannot speak for the quality nor specs of the ebay item I can and will vouch for thermal radiant barrier. We have installed tens of thousands of feet of it. Typically Dupont Tyvek and it runs a couple hundred bucks a roll. Night and day difference. Worth every penny. You litterally can feel a pretty significant difference by simply walking from one thermal area to a non thermal area. Nice. Put it on attic rafter not the attic floor. You loose MUCHO benefit if you put it on floor, your attic would still be an oven.

However, given we use spray foam insulation now, we have not put in the barrier. Would like to learn more bout the added benefit of both.
 
68sting said:
I.....wondered if this would be a wise investment of my time and money before I blow more insulation in.
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I too have thought about this and done some investigation.

From what I learned, it makes the most economic sense if your home is located in the southern part of the USA (where the summers are hot). The benefits of installing it in Michigan or New England make less economic sense.

Also, it helps most on south-facing portions of your roof. Installing it on a gable wall of a roof that faces north is worthless.

It does raise the temperature of your roof surface, which could contribute to more roof material decay. The material reflects heat energy from the sun so it has to go somewhere and that's the 2x4's and roofing surface.

I added two rooms to my house back in 2001 and was required by the California building codes to use a radiant barrier. (No big deal since I would have done it anyways.) I purchased plywood with the barrier installed. For new homes, the re-installed stuff on the bottom of plywood makes good sense to me. Crawling up in the attic and stapling it to the bottom of the roof deck did not appeal to me.

On the eBay ad, I did not see a close up of the actual material. I have seen, what I thought was good stuff, at the lumberyard and it looks like thin bubble wrap (1/8 to 1/4 inch) with aluminum foil on both sides. Also, the over-the-top effort at ad copy make me suspicious :lol: 10 rolls of Reynold's aluminum foil could be the "product" they send.

John
 
I bought mine from radiantguard.com. I got the "ultra" and its tough stuff. You can't tear it with your hands. I'm stapling it to the rafters and allowing the hot air to travel up between the rafter bays to the peak where its exhausted. I can feel the difference as I move from an area with barrier to an area without. I had some temp sensors logging data for awhile. On 10/10/2007 at 4pm, the outside temp was 82F, the sheathing temp was 105F, the temp on the barrier was 94F. That's about 10 degrees not coming into the attic on a relatively cool day. It'll be interesting to see the effect when its 100F+ outside. Phase 2 will be putting a layer down on top of the insulation (to keep the heat inside during the winter) and ductwork (extra protection and every bit helps).

Radiant barrier needs some air space behind it to be the most effective. The temp of the barrier where its stapled to a rafter is about 3 to 4 degrees higher than the temp between the rafters. This indicates direct heat transfer through the wood or whatever material its touching. Doh.

I would avoid the bubble wrap type stuff. My experience with any thin plasticy stuff is that after a few years in the heat it gets brittle and cracks.
 
I would avoid the bubble wrap type stuff. My experience with any thin plasticy stuff is that after a few years in the heat it gets brittle and cracks.
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not sure what it was originally designed for, or other uses it might be marketed for, but I've only seen 'metalisized bubble wrap' used for insulating ductwork (instead of fiberglass), I would think it could handle the heat . .
 
As others have said, it makes much more sense in the Southern climate where the sun is more intense and temps are higher. We just finished building a new home in FL, and many of the new homes put radiant barrier on the underside of the roof sheathing. We decided to go a different path. We sealed our attic space (no ridge vents, soffit is sealed, no other venting) and installed Icynene. This is a special type of spray-on foam applied to the underside of the roof and between any wall studding before drywalling. You do NOT insulate the floor of the attic when using Icynene.

On the hottest days of the year, the attic space will not get more than 10 degrees warmer than the living area. Though I haven't been in the house during the summer, yet, Southwest Florida can still get days in the mid-80's during the winter. I've been in the attic in the middle of the afternoon when the outside temp was 86 and the sun is shining, and could barely notice a temperature difference. You also don't have to insulate the duct work for HVAC since the attic air doesn't heat the ducts. As a bonus, besides energy savings, the house is much quieter because of the Icynene insulation. Plus, being in hurricane country, the sealed attic space won't allow wind penetration into the attic when the wind blows. My builder is so impressed, he's doing it in the new home he's building for himself.

For those interested, you can read about Icynene here.

Kevin
 
After reading the Icynene website, it seems like it is the same as spray on foam. I complete agree with its benefits and value but if you are a do-it-yourselfer then try Handi-Foam which is sold here
 
Kevin L said:
As others have said, it makes much more sense in the Southern climate where the sun is more intense and temps are higher. We just finished building a new home in FL, and many of the new homes put radiant barrier on the underside of the roof sheathing. We decided to go a different path. We sealed our attic space (no ridge vents, soffit is sealed, no other venting) and installed Icynene. This is a special type of spray-on foam applied to the underside of the roof and between any wall studding before drywalling. You do NOT insulate the floor of the attic when using Icynene.

On the hottest days of the year, the attic space will not get more than 10 degrees warmer than the living area. Though I haven't been in the house during the summer, yet, Southwest Florida can still get days in the mid-80's during the winter. I've been in the attic in the middle of the afternoon when the outside temp was 86 and the sun is shining, and could barely notice a temperature difference. You also don't have to insulate the duct work for HVAC since the attic air doesn't heat the ducts. As a bonus, besides energy savings, the house is much quieter because of the Icynene insulation. Plus, being in hurricane country, the sealed attic space won't allow wind penetration into the attic when the wind blows. My builder is so impressed, he's doing it in the new home he's building for himself.

For those interested, you can read about Icynene here.

Kevin
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We did the entire envelope system in Icynene. As well as high-end windows with a thermal break and a special glass that reflects heat. And a SEER 19 HVAC system. Between the windows and the Icynene, the HVAC guy did his heat load calculations like 3 times because he couldn't believe that we could cool our house here in Texas for what it was saying.

We've been in the house for a year now and our winter electric bills were within $100 of our summer ones. Also, I can walk in the attic in the dead of winter or heat of summer and it's maybe 10-15 degrees different than the house.

This stuff works.
 
Sounds like you did the same as us, Randy. The HVAC contractor we selected is different than the contractor our builder uses. But since it was a custom home we designed, my builder was very flexible on who we could use as some of the subs. The reason I picked the HVAC guy we did is he understood how Icynene changes the load calcs and that those that don't oversize the systems leading to dissatisfied homeowners. We also have a 19seer (Trane XL19i) and a 16seer (Trane XL16i) along with a zoning system. He said most of the time the XL19i will run on the small compressor (it's a two-compressor unit), saving us considerable money. I haven't been through a summer yet, but I'm confident we'll see results like you.

Kevin
 
Kevin L said:
As others have said, it makes much more sense in the Southern climate where the sun is more intense and temps are higher. We just finished building a new home in FL, and many of the new homes put radiant barrier on the underside of the roof sheathing. We decided to go a different path. We sealed our attic space (no ridge vents, soffit is sealed, no other venting) and installed Icynene. This is a special type of spray-on foam applied to the underside of the roof and between any wall studding before drywalling. You do NOT insulate the floor of the attic when using Icynene.
..........
Kevin
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This post is quite accurate. A radiant barrier does work well for conventional vented attics (which themselves make little sense in a hot humid environment), and better yet (for that same hot, humid environment), use the spray foam (which should completely seal the house at only the exterior surfaces like a giant Igloo cooler) and forgo the barrier (which would be covered by foam and negate any effect on the underside of the roof deck). Dang...finally go to use my engineering degree!!

Smarty P.E.
 
Thanks for the info.. I live in Colorado with a mild climate. I'm around 6600ft and the sun is intense at this elevation even thought the temps are generally mild. I think this could benefit me. Is there any way this won't pay for it self over time regardless of our location?

Lance
 
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