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

RooferJim
www.jbennetteroofing.com

 

OSB out....CDX -in

 

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...ository=BP&elementid=4916+radiant+barrier+roof+decking&hl=en&ct=clnk&cd=7&gl=us

 

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...ository=BP&elementid=4916+radiant+barrier+roof+decking&hl=en&ct=clnk&cd=7&gl=us

Ed, What do you think of that product?

 

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

 

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

...So very true ....

 

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.

 

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.....

 

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.

 

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?

 

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?

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.

 

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.

 

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.

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?

 

No that is not overly cynical, just reality.

Ed

 

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

 

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

Ed

 

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.

 

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

 

havent seen you around in forever man!

 

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

 

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.