# Foil Backed OSB



## DaveHembree (Apr 23, 2007)

Just wondering from the group the opinion on using foil backed OSB for roofing. I realize the ongoing debate on OSB vs. Plywood, but that aside - is it worth the extra cost to use Foil backed OSB vs. regular OSB? I have heard that the foil backed OSB will reduce the heat in the attic and thus *should* help lower the utility usage in the house.

Just wondering if anyone has any real world experience with this?


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## RooferJim (Mar 11, 2006)

I have learned from years of experience that all OSB is unsuitable for a subroof. Get CDX plywood .

RooferJim
www.jbennetteroofing.com


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## AtlanticWBConst. (May 12, 2006)

OSB out....CDX -in


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## Ed the Roofer (Jan 27, 2007)

The foil faced "PLYWOOD" is available if you choose to utilize this concept. Chech out the following link regarding Plytanium from GP.



http://64.233.167.104/search?q=cach...barrier+roof+decking&hl=en&ct=clnk&cd=7&gl=us


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## AtlanticWBConst. (May 12, 2006)

Ed the Roofer said:


> The foil faced "PLYWOOD" is available if you choose to utilize this concept. Chech out the following link regarding Plytanium from GP.
> 
> 
> 
> http://64.233.167.104/search?q=cach...barrier+roof+decking&hl=en&ct=clnk&cd=7&gl=us


 
Ed, What do you think of that product?


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## Ed the Roofer (Jan 27, 2007)

I have no personal experience with it, nor do I personally know anyone who has made their position clear on the product whom I trust.

The reports I have read in the past and now seem to indicate it maintains a cooler interior temperature.

As with any new product, the jury is still out.

Ed


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## AtlanticWBConst. (May 12, 2006)

Ed the Roofer said:


> .... As with any new product, the jury is still out.
> Ed


...So very true ....


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## AaronB (Jan 29, 2005)

OK, here are my thoughts on foil backed products marketed as radiant barriers....

Its B.S. Foil facing can only reflect heat before it becomes heat. It can only reflect light. After the sun's light has made contact with your roof, the light energy is changed to heat energy. The foil can certainly absorb and radiate heat, but it cannot reflect that heat unless it is on the very outside, exposed to the UV light.


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## AtlanticWBConst. (May 12, 2006)

AaronB said:


> OK, here are my thoughts on foil backed products marketed as radiant barriers....
> 
> Its B.S. Foil facing can only reflect heat before it becomes heat. It can only reflect light. After the sun's light has made contact with your roof, the light energy is changed to heat energy. The foil can certainly absorb and radiate heat, but it cannot reflect that heat unless it is on the very outside, exposed to the UV light.


Not trying to start anything.....

Do you have links to information or studies regarding the points you are stating? As I wrote, I have never used the product.....


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## AaronB (Jan 29, 2005)

I do not....it was learned in 6th grade science class. Metals absorb and conduct heat. No mfg rep has ever been able to explain it otherwise.


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## parkerfairfield (Apr 28, 2007)

AaronB said:


> I do not....it was learned in 6th grade science class. Metals absorb and conduct heat. No mfg rep has ever been able to explain it otherwise.


Hmmm.

Well, since we're all opining.... I sold a lot of LUMINOX.


The reason why ... is because of the 'science' they quoted. And yes, this quote could be purchased crap... a la the Institute that certified cigarettes made you cool and they have nothing to do with cancer.

The link to their PDF is here.

the Spiffy quote is here: Found in bottom right of page 2

Geoscience LTD, an independent testing facility, has documented through the use of ASTM C-236 test methodology the following: • Roof temperatures of up to 123° yield 21-22% air conditioning energy savings. • Roof temperatures in excess of 123° yield savings between 25-30%. In other words, the hotter your roof deck gets, the more you save on your air conditioning bill. • For a copy of the report contact Ainsworth at 1-877-661-3200.


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## portland (May 3, 2007)

*Study says foil-sheathed OSB may not help much–might hurt.*

http://www.ornl.gov/sci/roofs+walls/radiant/index.html
http://www.ornl.gov/sci/roofs+walls/radiant/rb_02.html

Suggests that at best, the use of various types of radiant barriers might reduce cooling needs by 2 to 10 percent, in summer, in a warm climate. HOWEVER, a radiant barrier may also reduce beneficial heating in winter. Also, the more standard insulation you have in your attic (R-19 should be a minimum), the less difference a radiant barrier would make. 

Short story: in summer, it may not be worth the added cost; in winter, the jury is still out whether it helps at all–or maybe even hurts. Attic insulation (batts or blown-in) is a sure thing in all climates and seasons.
Save your money?


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## Ed the Roofer (Jan 27, 2007)

A little more information about radiant barrier decking.

from buildingscience.com 

Ed

*Effect on Shingle Life*


In general, shingles installed on unvented attic assemblies operate at a slightly higher temperature. This has impacts on the durability of roof assemblies. A 2 or 3 degree F. rise in average temperature is typical for asphalt shingles and a corresponding 10 degree F. rise in average temperature for sheathing (Parker & Sherwin, 1998; Rudd & Lstiburek, 1998; TenWode & Rose, 1999) 

All other things being equal, applying the Arrhenius equation (Cash et.al, 2005), a 10 percent reduction in useful service life should be expected. This is comparable to the effect of the installation of radiant barriers. What is more significant to note is that the color of shingles and roof orientation have a more profound effect on the durability of shingles than the choice of venting or not venting (Rose, 1991) – double or triple the effect of venting/non venting.


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## parkerfairfield (Apr 28, 2007)

portland said:


> http://www.ornl.gov/sci/roofs+walls/radiant/index.html
> http://www.ornl.gov/sci/roofs+walls/radiant/rb_02.html
> 
> Suggests that at best, the use of various types of radiant barriers might reduce cooling needs by 2 to 10 percent, in summer, in a warm climate. HOWEVER, a radiant barrier may also reduce beneficial heating in winter. Also, the more standard insulation you have in your attic (R-19 should be a minimum), the less difference a radiant barrier would make.
> ...


 
To start out ... I hail from New England... my mom lives in 'the Birth place of Vermont' - Windsor.

I (semi-unfortunately; it's complicated like most things in life) live in California.

Like many of the 'cool roofs' YMMV (your mileage may vary).

Funny anecdote ... we were putting a PVC roof on in April 2005... in Gilroy, CA - the 'Garlic Capitol' of the world. Anyway, at 7:30am there was 1/8 inch of ice across the WHOLE roof. Go to Google... you'll see that for a standard BUR, it shouldnt be cold enough. POINT = it is a COOL ROOF all the time... which is why you'll see ALL of the marketing material re: 'Cool Roofs' talking about the "COOLING SAVINGS" - not the ENERGY SAVINGS (as was pointed out, the winters will result in an INCREASE in heating costs unless the roofer salespeople (a) are educated to this fact (b) are good enough educators to TEACH this ROI concept to the homeowner.

Finally, if you're in COLD areas... you've PROBABLY enough insulation to deal with the fact that you're not going to be heating up the attic the additional few degrees. It's my GUESS that if it is tit freezing cold outside, an additional 2, 5 or 10 degrees F drop in attic temp is not going to have a big hit on your heating bill.

Just my R-4.


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## parkerfairfield (Apr 28, 2007)

Ed the Roofer said:


> A little more information about radiant barrier decking.
> 
> from buildingscience.com
> 
> ...


Ed, this is a FANTASTIC point.

Let's pretend Bill Gates dies and leaves all of his money to you. You decide to buy Certainteed or OC.

Would you then radically alter the warrantees on all of the BLACK shingles that are currently offered with the same warrantees of the more 'yellow' or 'gray' versions? 

NAH.

You'd rely on the fine print... like everyone else - at least, the average LAWYER would.

Non-vented... well in this market, that voids the mfg warranty.
And Elk, GAF, and C'teed are still mute on the usage of foil-backed ... and 'allow' it when pressed.
Therefore, they are acting like LIFE INSURANCE agents - relying upon the law of averages:
.... the avg house will be sold 2x before 'premature' failure...negating the warranty
.... if not sold 2x, the avg homeowner won't have the paperwork... negating the warranty CLAIM
.... someone with the paperwork , when learning of the pitiful little amount will be given them in the year 2026 will just decide it's not worth fighting for it

Meaning they'll pay out 1% of the POTENTIAL claims.

Overly Cynical?


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## Ed the Roofer (Jan 27, 2007)

No that is not overly cynical, just reality.

Ed


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## wildhorses (Jun 27, 2008)

*Foil OSB*



> *AaronB * _OK, here are my thoughts on foil backed products marketed as radiant barriers....
> 
> Its B.S. Foil facing can only reflect heat before it becomes heat. It can only reflect light. After the sun's light has made contact with your roof, the light energy is changed to heat energy. The foil can certainly absorb and radiate heat, but it cannot reflect that heat unless it is on the very outside, exposed to the UV light._


Foil reflects heat and radio energy NOT ONLY light energy. Aaron, you might talk to NASA to see if foil works on their spacecraft. The amount of heat the foil "absorbs" is minute due to the thinness of the material making the foil a poor "radiator" of heat. I guess you should avoid using Reynold's Wrap 'cause it's only made to reflect light. And it's not "_the UV light"_... Heat is on the Infrared end of the spectrum. Hummmm, maybe that's why my suntan lotion doesn't keep me cool.

See this department of energy website:

http://www.ornl.gov/sci/roofs+walls/radiant/index.html

It's from the guys at the Oak Ridge National Laboratory. Not exactly Aaron's 6th grade science class?



AaronB said:


> I do not....it was learned in 6th grade science class. Metals absorb and conduct heat. No mfg rep has ever been able to explain it otherwise.


You've got crappy reps. LP and GP bought up the little companies that made the original "KoolPly". I guess they just needed a place to toss some bucks. After reading your logic Aaron, I think you're in the correct business... thank god you're not in the radiant heat flooring business or you'd have your clients wearing metal shoes to keep their feet warm.

Oak Ridge studies show savings up to 17% on utilities and negligible heat gain into the roofing materials (1-2%. That's probably less than the difference between various shingle colors). The foil blocks RADIANT HEAT. I built a 3400 Sq Ft house in Dallas Texas and saved hundreds of dollars in air conditioning bills versus my neighbors with similar houses and no radiant barrier.

In the winter the foil helps keep heat radiating OUT through the roof. Remember that casserole with foil on top?

So I would heartily endorse the foil product. It's roofers like Aaron et al that have helped keep America's energy foot print so large. Ed, the jury is not "still out". The product is proven and will pay for itself in 3-5 years.

I don't work in the roofin' bidness but if I did I would put a foil backed product on every roof I did. OSB vs plywood? Sure. Use which ever you want... you can even staple many radiant barrier products to the sheathing yourself. 

As far as roofing warranties, I live in Texas where a roof gets pounded by hail approximately every 7 years, so any shingle warranty is just something to help you get to sleep every night... much like the worthless home warranties that builders sell to clients... now those are a joke...


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## the roofing god (Aug 2, 2007)

the foil has always been hot enough to mely vinyl siding,as such,I would expect the existing plywood to dry out,and delaminate much earlier than normal


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## comp (Jan 14, 2008)

the roofing god said:


> the foil has always been hot enough to mely vinyl siding,as such,I would expect the existing plywood to dry out,and delaminate much earlier than normal


didn't think of that


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## Ed the Roofer (Jan 27, 2007)

I would be very interested to see what WildHorses has to say in thay regard.

Ed


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## Construction15 (Jul 7, 2008)

The foil backed OSB or Plywood are effective in climates where you run your AC a lot in the summer. If you are in a moderate climate it is not worth the cost.


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## MasterBuilder (Aug 31, 2011)

AaronB said:


> OK, here are my thoughts on foil backed products marketed as radiant barriers....
> 
> Its B.S. Foil facing can only reflect heat before it becomes heat. It can only reflect light. After the sun's light has made contact with your roof, the light energy is changed to heat energy. The foil can certainly absorb and radiate heat, but it cannot reflect that heat unless it is on the very outside, exposed to the UV light.


Maybe, AaronB, continuing you education past primary school would have kept you off of roofs. I'd like to know which law of Thermodynamics you're referring too. <link removed>


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## Wildsmith (Jul 24, 2013)

AaronB said:


> OK, here are my thoughts on foil backed products marketed as radiant barriers....
> 
> Its B.S. Foil facing can only reflect heat before it becomes heat. It can only reflect light. After the sun's light has made contact with your roof, the light energy is changed to heat energy. The foil can certainly absorb and radiate heat, but it cannot reflect that heat unless it is on the very outside, exposed to the UV light.


Sounds to me like you have never used this product. I recently built two identical restroom buildings, about 1/2 apart, and neither had ANY shade what so ever around them. the first building I built, I used Regular 7/16'' plywood decking, Titanium UDL underlayment, and 40 year shingles. The second building I built, had the same exact exposier to the sun, only I used foil backed 7/16'' plywood on this building. The building with the foil back plywood was right at 30 degrees COOLER, than the other building! Both building temp readings were done about 5-10 minutes apart, at the same time of day. Bottom line.....It Works~!:thumbsup:


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## the roofing god (Aug 2, 2007)

and ,So the question of whether or not,,the plywood would bake itself to delaminate,and turns to dust in much faster time,like fire treated plywood,,isn`t a thought,,seems that it would be a natural occurrence with the radiant heat repelled back at the decking,,,so what about it? :whistling2:

just saying the fire treated plywood is a large safety issue today,as a result of very similar circumstance


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## JWilliams (Sep 22, 2010)

havent seen you around in forever man!


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## Gary in WA (Mar 11, 2009)

http://www.greenbuildingadvisor.com/blogs/dept/musings/radiant-barriers-solution-search-problem


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## AtticFoil.com (Aug 27, 2013)

On new construction, bang for the buck you can't beat spending the LITTLE extra money for radiant barrier decking. It's only a couple bucks per sheet more and worth it since there is no additional labor. Radiant barrier decking works off the emissivity quality of aluminum which is the ability NOT to easily convert energy into radiant heat (think of a foil wrapped potato will stay hot longer a potato not wrapped with foil). As for increasing the roof temperature? I've measured many roofs and typically the roof/shingle temperature increases less than 10 degrees over a radiant barrier. I don't think there is going to be a significant difference in the life of the shingles or deck whether the max temperature is 160º or 170º. Here in Texas many areas are actually requiring radiant barriers on new construction.


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