Cellophane strip found on / between asphalt roof shingles: forensic engineers comment.

Generally manufacturers advise that roofers can and should leave the cellophane separator strip alone when installing asphalt roof shingles as during installation it will automagically find itself harmless and out of the way of the glue strips of the shingle course below.

But two forensic engineers have explained that in a few odd cases the cellophane separator strip may fail to remain where it should when the shingles are separated from the bundle, and that those strays should be removed, as we explain below.

Forensic Engineers Views on Cellophane Strips on Asphalt Roof Shingles

Here we provide field photographs and observations from forensic engineers about the cellophane strips used between asphalt roofing shingles. Both engineers Andrew Kester and James Skees conclude that the strips serve a purpose while the shingles are still in their original bundle, that the strips are normally left alone, and that in odd cases of the cellophane not behaving itself it may indeed need to be pulled out of the way.

Asphalt Shingle Cellophane Strips Sometimes Don't Stay Where they Should

Andrew Kester, P.E.

Here is an example of a cellophane strip that stuck to the top of a shingle while in the bundle, likely during shipping or storage, and the installer did not remove it. Surprisingly, it was an old roof with no real wind damage as a result of the strips preventing the sealant strips from activating, and you can see from the pics the cellophane ultimately didn’t even full bond to the strip (as designed).

I believe that the cellophane strip became stuck to the adjacent shingle’s sealant strip during shipping and handling, in the bundle, not once put on the roof. It actually did the job it was supposed to do and prevented the actual shingles from sticking together.

In this case, the installer should have removed the cellophane or discarded this shingle. Removal was needed because the cellophane was stuck in the wrong place - atop the adhesive strips.

In other words, the only time you should remove the cellophane is if it has come off and become stuck to another shingle. This is very, very different than removing the protective strip when it is in its proper place on the bottom of the shingle. Leave it be!

It is important to note that this is probably a 15-20 year old roof, and perhaps the new cellophane strips are better adhered to the shingle or designed to not be removed at all. This is what I would do if I was designing shingles, make the strip irremovable so there is no way this could happen

Maybe this only happened with a few shingles, as I only found the cellophane strips covering the adhesive strips in one specific area, likely indicative this occurred in just one or two bundles that were improperly stored. You can see that the cellophane wasn’t really sticking to the adhesive that well (per design), though it has been 15+ years.

The roofers who installed this person’s roof also high nailed a lot of the shingles so they failed from slippage. [Below]

The pen in my photo [above right] was inserted in the nail hole, showing it was high and missing the nail strip and shingle overlap. The cellophane strips on these shingles were in their original and correct position.

Two major mistakes on one roof, likely due to an inexperienced installer. It's remarkable that this roof lasted this long, probably over 15 years in Florida! (This area hasn’t had a major wind event in a long time.).- A. Kester, 11 Feb 2015

- Andrew Kester, P.E. 60993 is a forensic and structural engineer practicing in Florida. See also ROLL ROOFING, ASPHALT & SBS.

Mr. Kester continued:

It is a bit unusual to have a roof with two distinct installation errors. The cellophane strip ultimately had no deleterious effects on the roof, but incorrect nailing above the nailing strip caused the shingles to fail prematurely [as improper nailing invites wind damage to the roof - Ed.]

Here is a high nail failure on a different roof with nice shingles, less than 5 years old! I felt bad for the homeowner.

Both of these roofs ultimately failed due to GRAVITY loading on the shingles, not wind!

Asphalt shingle cellophane strips from a second forensic engineer:

James A. Skees, PE

The only time the cellophane strip protects the seal strips is while they are still in the package.

I am a forensic engineer who works for insurance companies. Occasionally I find a limited number of shingles on a roof did not seal because the cellophane strips have attached to the seal strips instead of staying on the underside of the shingles in the package. Let me try to explain that better.

The cellophane strips are attached to the center of the undersides of the shingles at the factory. The seal strips are on the top side at the center of the shingles.

The only time the cellophane strip protects the seal strips is while they are still in the package. Occasionally stacks of shingles are left out in the sun before they are installed, sometimes while at the distribution center, sometimes at the factory, sometimes on the truck that delivers them, sometimes in stacks in the yard before they are installed, and even sometimes across the roof before the roofers open the packages.

In those cases (you see above they can be many cases), the solar radiation can activate the sealing strip adhesive on the top shingle or two or maybe even three, and the cellophane attaches to the top side of the shingle covering the adhesive when the shingles are taken out of the bundle.

Most of the cellophane strips have the instructions not to remove printed on the surface. However, it will be printed in reverse when it sticks to the seal strip (since it is intended to be read from the bottom). However, to most of us that read English it still admonishes that it not be removed, even if it is printed backwards.

With the cellophane in place covering the sealant, the shingles installed over those individual two or three (per bundle) will never seal. This leads to blow-off failure more often than you would think.

I find several like this every year and there may be as many as ten to 15 complete missing shingles on a single roof because of the cellophane sticking to the seal strips.

That is usually enough to put the insurance company on the hook for an entire roof that somebody installed incorrectly.

- James A. Skees, PE [7]

Conclusion: Leave the Cellophane Strip In Place Unless It's in the Wrong Position

Normally, leave the cellophane strips alone and in their original place

You should leave the cellophane strips in place on the shingle back surface (which is ok with the manufacturer) so long as the strip is intact and in its original position.

About deliberately pulling off all of the cellophane strips as was suggested by some roofers: if you are in a high wind area and are going to be adding additional sealant anyway, this step is probably unnecessary and is not specified by the manufacturer.

Earlier, in the 1990's we were concerned with excessive bonding between shingles that combined with a lack of tear resistance to lead to premature roof failures due to thermal splitting. It's fair to add, however, that the root cause of that problem was a specification that led to inadequate tear resistance, not an innate fault with shingle tab bonding.

See CELLOPHANE STRIP ADHESIVE ADEQUACY in HIGH WIND AREAS

Remove cellophane strips from roof shingles if the strips are in the way:

If the cellophane strip has become debonded from its original and correct position on the bottom of a shingle prior to installation, it may then become harmful debris that may prevent proper bonding of the shingles and absolutely must be removed and discarded. If this is not done, then you get the situation that was encountered below, where the cellophane covered the strips of another shingle and this prevented them from bonding properly. This would also likely void the shingle manufacturer’s warrant due to an error in the installation.
- Thanks to A. Kester, P.E. for this clarification, private email 16 Feb 2015

Watch out: Do not leave loose cellophane strips nor any other extraneous debris on a roof, especially when installing new roof shingles as those materials may interfere with proper roof tab sealing and may lead to future increased shingle blow-off in windy conditions.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: why are there glue strips or spots on asphalt shingles ?

(Apr 2, 2014) Pat said:

I have installed the shingles on my house and removed the cellophane and in the 20 years since then I have not lost one shingle. I moved to a senior housing development and the roofs here are 14 years old and low and behold we had a wind storm and shingles are all over the place along with the cellophane and now a contractor is going to try to sell us to replace all the houses that were not damaged to get new roofs. What ever happened to 20 or 25 year shingles?

Why put the glue strips in the first place?

Reply:

Pat, the glue strips are there to allow the single taps of each upper course to bond to the lower course (with a bit of time and heat from the sun). This bonding in turn prevents wind-damage that otherwise lifts the shingle tabs and blows them off of the roof.

The people with the most at stake in this argument are the roofing manufacturers- we should follow their advice.

Leave the cellophane or paper release strip in place; it's not interfering with bonding, it's job is to prevent the shingles from sticking together while still in the bundle. When the shingles are installed in offset courses up the roof the release strip stuck to the under-side of an individual roof shingle is no longer covering the wind-uplift-damage-prevention glue spots or strips that are exposed on the upper surface of the shingle in the course below.

This is of course a separate question from your last sentence.

Question: reader finds experts confirm: leave the release strips in place but still disagrees

(June 20, 2014) Mike O said:

I called the Roofers Union and they backed up the contractor and said leave the cellophane on.
It will disinigrate ( like his brain )
The dumbest statement that I ever heard was next:
The cellophane is for shipping. What a moron. So what he just said to me is that the tar was
placed on the shingle TO HOLD THE CELLOPHANE IN PLACE!!!!!!
That's called "Back up the love roofer"
THE REAL STORY IS THE TAR was put on the shingle to give it added strength and the cellophane was placed on the tar to prevent them from sticking to each other. STICKING key word The tar strip
is there to give STICKING POWER TO THE SHINGLE and stop them from lifting so rain can get in under them!!!!!!!!!!!!!!!

I have had my roof since 1999 and only 5 shingles blew off and they were the 5 shingles that still
had the cellophane on them.

Reply:

Mike, we have researched this question with great care to find and cite authoritative sources and to put the arm waving speculation. The article above gives correct information. Please take another look and let me know if anything you see there is unclear.

1. The glue strips or spots on shingles are there to bond down the tabs of the next upper shingle course to protect against wind-uplift damage. The release strips, once the subsequent shingle course is nailed in place, are no longer atop the glue strips on the shingle in the lower course. We leave the release strips in place because
2. The cellophane or silicone-treated paper release strips on the shingle under-side are doing no harm
3. The cellophane or silicone-treated paper release strips on the shingle under-side are not in the way of the now-exposed glue strips found on the upper surface of the shingle course below.
4. There is risk of shingle damage if you pull these release strips off

Question: reader doesn't understand that staggered shingle courses eliminate release-strip worries

(June 21, 2014) Anonymous said:

Try this simple logic: The manufacturer wouldn't have put the goo on the shingle unless it was going to be used to stick to another shingle. Obviously the cellophane strip is to keep it from sticking to other shingles while in transit. The only unanswered question is: Does the cellophane dissolve swiftly after installed, presumably due to the heat of the sun? If yes,the goo would be allowed to serve its purpose - eventually. How long or what minimum heat does it take to dissolve the cellophane? If the cellophane does not dissolve, the goo was put on for no reason whatsoever. If it does dissolve, removing the cellophane manually allows quicker sealing of the goo to the underlying shingle. In not taking the time to remove the cellophane on installation, the installer is gambling that a high wind won't occur before the tape dissolves. I presume also that, if the cellophane is removed, it opens up a lot of opportunities to touch down the shingle a bit crooked, probably without the ability to lift it back up and straighten it. That is another cost factor - lost time and damaged shingles.

Reply:

Simple but mistaken logic. Please read the article above. You'll see that at installation the self-adhesive tar strips and the cellophane strips remain nowhere near one another once the shingles are installed - see the arrows on our illustration, and also that forced tearing off of the cellophane is not recommended by the manufacturer, in part because doing so can cause shingle damage.

Question: reader questions why there is sticky stuff on the underside of the shingle

(July 30, 2014) pete ianuzzi said:

so why is there sticky stuff on the bottom, just to hold the cellophane tape in place?? and did mfr.'s original require you to remove this seal. I seem to remember reading that in the small print many years ago...40+years ago

Reply:

of course not Pete

The functional sticky stuff is the sealant that is present on the upper surface of the shingle in the course below. That sealant is heated by the sun, sealing the next upper course shingle tabs down on to the lower course of shingles.

A small amount of adhesive between the release strip (cellophane or silicone impregnated paper strips) holds the release strip in place bonded out of the way to the underside of the next upper course of shingles. It's not in the way and should be left in place.

Question: reader doesn't understand glue strips, shingle course offset, and does not agree with instructions from the shingle manufacturer

(Aug 8, 2014) Anonymous said:

I just read an article at Inspectapedia.com/roof/shingle....Anonymous below is correct!!!!! Although they go on to
say the bottom line is "NO" you do not need to remove it...There IS a "YES" argument....The YES argument makes more sense
then DanJoeFriedman.....The YES indicates that in high wind areas or areas subject to High WInds and Heavy rains, or if the roof was laid in cooler weather, the cellophane probably will not disintegrate immediately thus allowing dirt or
particles to get under the shingle which MAY NEVER SEAL PROPERLY. IN ADDITION TO REMOVING THE CELLOPHANE, IT IS NOT A BAD IDEA TO APPLY EXTRA SEALANT!

ROOFERS don't want to remove it because of 2 reasons....it takes too long AND if your working like a mad man
and just throwing them down, there is a chance that a misalignment would have to be redone and a shingle wasted.

ITS ALL ABOUT THE $

Reply:

Anonymous

One simply cannot imagine any economic benefit to roofing shingle manufacturers that would accrue from your argument.

But you are part of a considerable group of folks who have trouble picturing where the release strip ends up and where the actual glue strips or spots end up as shingles are placed on the roof. Check out the photo with arrows in the article above and you'll see why leaving the release strip alone is harmless and is recommended.

I should add that in a few instances we have actually seen shingles damaged by the pulling off of the cellophane strip.

Bottom line: remember that the manufacturers have a lot at stake in the successful installation and life of their product. While there may be some arguable compromises on product quality, life, warranty and other worries, following the roof shingle manufacturer's own instructions on how their product should be installed is the smartest approach to roofing.

It is unfortunate that so many people are confused about the cellophane strips and roof shingle tab sealant, particularly as the manufacturers and other experts have written so clearly on the matter. What we have published on this matter is hardly personal opinion. It's researched and cites authorities on the topic.

You are mistaken in your "all about money" claim in this case - the manufacturers don't make any more money with or without cellophane strip removal, but they do know what leads to product success or product failure - which is of great import, and which is why shingle tab sealant is provided in the first place - to protect against wind uplift.

It would appear that your confusion and that of some other readers stems from failure to notice that when shingles are taken out of a bundle (in which the cellophane on an upper shingle's underside prevents it from adhering to the adhesive tabs on the upper surface of a shingle below), and then placed onto the roof in successive courses, the underside of the upper shingle is a good 4-6 inches higher up-roof (depending on the shingle exposure) than the tab adhesive spots of the shingle below.

Thus the cellophane, left in place as the shingles are installed, is now here near the sealant tabs so it can not interfere with shingle adhesion.

Take a look at the annotated photograph just above in this article and you can see that shingle layout.

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