Cracked shingles

[Ed Fako]

The OP needs to verify what I can not tell for sure from the photos if the other colored pieces are a laminated add on or an applique add on, such as the Certainteed Horizon shingles.

Although I am a proponent of proper balanced attic ventilation, I highly doubt in any extremes, that a shingle would contain full body cracking from improper ventilation alone in a stated 5 year period of time.

The applique method from the CT Horizon shingles had applied too much excessive asphalt flooding for the architectural style shingle appearance.

From my previous life as a hot tar roofer, and anyone who knows a hot tar roofer can verify this point, if you put too much asphalt on, it will crack very shortly in its life. When the asphalt cracks, anything that is connected to it cracks as well.

My best guess, without knowing the brand of shingle is a manufacturing defect.

Ed

[Marcel R. Cyr]

I have to agree with Dale and Ed on this one, because I can relate to both the mopped on asphalt and pitch roofs and unventilated attics and the symptoms of the above posted pictures, if in fact are only five years old, are definitely defective. IMHO

Marcel
</IMG></IMG>

[klott]

One thing we know for sure is that they are cracked and dried out, while poor ventilation may not be the cause of failure on these particular shingles, you can bet the added heat helped in their failure. of course heat has an aging effect on shingles, if it didn't then the Sun would have no adverse effects on them. You could simply coat them with a UV inhibitor and they would last forever. They crack and curl because they dry out, they are petroleum based asphalt and they loose their oil by evaporation and we know heat speeds up evaporation. poor sealing during manufacture will cause premature failure also, not to mention color. Light reflects heat and dark absorbs it. So I would say everyone here may be right. The shingles may have been installed 4 years ago, but they may have been made 20 years ago and stored outside. Note it, defer it and move on. IMO

[Brian A. MacNeish]

From an old post I made 6 or so months ago. If anyone has the below issue of EDU, please notify me .......mine has disappeared!!


" I'm thinking that virtually no one on these boards have ever had a subscription to the newsletter Energy Design Update or if they had they did not believe what they read. In the July 2006 issue (I believe;can't find my copy at the moment), a Building Science Corp reseacher measured roof temps of dark roofing materials in Jacksonville, FL during the month of August. Yes, he found that the unvented roofs had higher temps at their surface (the hottest part of the shingle since the sun hits there) but over the month the average temp rise on the unvented roof surface was something like .2 degrees F, not likely to cause shingle failure."

I'm to believe that this part of the US has very hot exterior temps yet the roofing material temps did not rise very much on dark shingles!!!!!! what does that say about the deterioration rate of the material....if it rises to 131 deg from 130, it will fail premturely?? And what about up north in Maine, Vermont, etc, will the same shingle fail much more quickly if the temp rises from 110 to 111 .......and how many days of the year will it get that hot as opposed to Florida and Georgia......the same shingle used down there should fail years ahead of those installed up north since the average operating temps should be at least 10- 20-30-40 degrees hotter!!!!

So you see that when the operating temp for the same shingles (vented or unvented) in north and south locations is so different and the south shingles are getting real hot (150-200 deg), a new quandary appears: Why aren't the southern shingles failing many years ahead of northern shingles due to the extra heat??? Doesn't appear to be a venting problem since a vented southern shingle will get to 130-40+ deg regularly while an unvented north shingle will rarely or never get that hot but still fail due to no venting???? If Dale is seeing 200 deg shingles in Arizona, they must have to replace them every 2 or 3 years!!!

By the way, what is the high temperature that causes a roofing shingle to fail prematurely??

[Roy D. Cooke, Sr]

Is this the one you want .
http://www.buildingscience.com/docum...ented%20attics

... Cookie

[Ed Fako]

Brian, I have that temperature in one of my favorites in at least one article, but I would not be able to find it in a timely basis.

If I recollect, it was about 170*, which at that temperature, the material begins to succumb to the excessive heat.

Also, as you well know, I totally disagree with the point brought up in your quote in your recent post. To accept that, after all of the years I have been walking on roofs would be ludicrous. Something is very wrong with that particular authors testing, results and conclusions.

But, if the venting/not venting discussion is to continue, I suggest reviving that other long thread, rather than completely hijacking the context of this one.

Ed

[Ed Fako]

Originally Posted by Brian A. MacNeish

From an old post I made 6 or so months ago. If anyone has the below issue of EDU, please notify me .......mine has disappeared!!

Could this be a link that would help you find the newsletter referenced?

http://www.buildinggreen.com/article...ume=15&Issue=9

Ed

[Barry Adair]

http://www.buildingscience.com/docum...c-ventilation/

[Brian A. MacNeish]

Originally Posted by badair

http://www.buildingscience.com/docum...c-ventilation/

From the article:
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)

my comment: When inspecting a roof with deteriorated shingles but we do not know it has no venting, can we measure the temperature difference of say between 120 deg and 123 and determine that "no venting" caused the failure......... or does it matter....it's so small!!



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.

My comments:
Background reading:

Common sense and chemical intuition suggest that the higher the temperature, the faster a given chemical reaction will proceed. Quantitatively this relationship between the rate a reaction proceeds and its temperature is determined by the Arrhenius Equation. At higher temperatures, the probability that two molecules will collide is higher.

My comments on the use of the Arrhenius equation in this situation:

IT'S A STRETCH!!!
The equation was developed for chemical reactions in liquids and gases (where atoms and molecules are free to move around and must collide to react thus forming a new chemical) to predict the rate of reaction and the amount of new materials created by raising the temperature of the solution of reactants. In shingles we have fixed, fairly stable materials that don't move around much!!! (you can bang 2 shingles together a long time and you won't get new chemicals, just beat up shingles!!) Yes, some violatile compounds are released upon exposure to air and the sun's rays and it will be more when the temps are higher.......but to state that the Arrhenius equation apllies here is quite a stretch:

(1) we generally have fixed molecules
(2) this is mostly a drying process that doesn't create new chemicals
(3) again they haven't tested but make reference of possibly being similar to a chemical reaction


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.


My comments:
So the colour of a shingle or its orientation will help it deteriorate 2-3 times faster than not venting!!! That's why some companies now accept unvented roof cavities.......maybe it's not that important.

Saying that lack venting caused the shingle failure when most likely it is shingle quality, color and orientation firstly and...........then venting is like saying not having a vapour barrier is responsible for vapour condensation in walls and attics when actually 98-99% of vapour movement into these areas is air movement and lack of an air barrier, not vapour diffusion which a vapour barrier slows down. We have to understand the true issues. To simply call the problem "no venting" may be irresponsible.


In the issues of heating/cooling, adding venting in some situations may actually increase moisture flow to the attic and increase heat loss from the dwelling in winter.



PS: Its funny that not many have tackled or mentioned the issue of shingle quality dropping when maybe we have a big problem there. Bill Rose has made coments in the Journal of Light Construction about this.

[klott]

Just because one person writes an article does not make it right, I base my judgements on experience and many other peoples opinions. I tend to believe all of the diagnosis offered here have a negative effect on shingles, and even more so when combined. many a theory have been accepted for years only to be disproven later.

[Marcel R. Cyr]

Everyone has an opinion, so here is mine for the one's that are interested in reading it. ha. ha.

The Hostile roof environment

Consider the conditions your roof must endure. First there is the intense heat of the sun, which scorches the surface of the roof and raises rooftop temperatures 50-75°F above ambient temperature. The sun's rays are relentless, especially during early afternoon hours. In addition to heat, the sun is the source of the ultraviolet radiation, which has been shown to degrade and accelerate the aging of the asphalt layers of the shingle. If not for the protective layer of the colored granules, roofing shingles would fail very quickly. Other factors such as moisture, pollution and physical effects (roof traffic, hail, snow loads, tree limbs etc.) all contribute to the aging and degradation of your roofing shingles.
For example, consider the common situation in which the roof is bathed in the intense heat of the summer sun. On such a day the rooftop may reach temperatures in excess of 160°F. Now imagine a cold front sweeping through the area, brining with it the violent thunderstorms that are a common occurrence during the sweltering days of summer. Almost instantaneously, the rooftop temperature drops 60-100°F as it's pounded with a summer shower. Thermal shocks such as this cause the roof deck beneath to expand and contract. placing a strain on the shingles. Year after year this process is repeated, resulting in cyclic fatigue of the shingles.
.
Day after day the shingles are exposed to the elements - sun, rain, heat and cold.
Your roof never has a "good" day.


The stresses created by thermal shock and the movements of the roof deck also increase the likelihood of surface cracking.

Cracking through the reinforcement


Depending on the style of shingle, the normal weathering characteristics described earlier may be a sign of more serious problems. For example, cracks across a typical three-tab shingle may be a sign of a weak reinforcement. This type of cracking threatens the waterproofing integrity of the roof and needs to be addressed immediately.



Vapor, Not Vents

Although there clearly are potential benefits from attic vents in heating climates, there are also disadvantages: Vents can be prone to snow and rain entry that can wet the insulation, and cold air blowing through eave vents can degrade the thermal performance of attic insulation.... In heating climates, attic ventilation usually provides a measure of protection from excessive moisture accumulation in the roof sheathing, but if indoor humidity is high and humid indoor air leaks into the attic, the use of attic vents does not guarantee that attic moisture problems will not develop.

Therefore, moisture control in attics in heating climates depends primarily on maintaining low indoor humidity levels during cold weather and on ensuring sufficient air tightness and vapor resistance (i.e. a vapor retarders) in the ceiling.
--1997 ASHRAE Handbooks, Fundamentals, 23.6


Warming Up to Unvented Roofs

The underside of the roof sheathing is where the real benefits of not venting roof assemblies are found. Field measurements and computer modeling show that, without attic venting, the temperature of the underside of the roof sheathing increases by 10°F-20°F.
In cold climates, this is an advantage. Unventing roof assemblies in most cold climates decreases the heating load by about 10%. That answers the energy question: Unventing attics in cold climates saves energy.

What about shingle temperature?
Well, the answer to that question is, don’t use asphalt shingles. They have many disadvantages anyway. They burn. They are sensitive to ultraviolet light. They can't be made to last more than 15 to 20 years--despite what the warranty says. Hail just kills them, and they off-gas horrible stuff. But they are cheap. And in cold climates, they are the roofs covering of choice.

When attics with asphalt-shingled roofs are left unvented, the operating temperature of the shingles increases slightly--on the order of 2%-3% of absolute temperature. This means that a black asphalt shingle roof that is typically at 150°F will be at 153°F-155°F. That 3°F-5°F increase can be important, since it translates into an approximate 15% reduction in the useful service life of the shingle. On a 15-year shingle roof, which means you may lose 2 to 3 years in service life.

Why is there only a 3°F-5°F increase in asphalt shingle temperature? Because radiation is the dominant factor in heat transfer through roof assemblies, and venting the roof does not affect the radiation heat transfer. Also, the underside of the roof sheathing is not an efficient plywood-to-air heat exchanger, so venting is of little importance in reducing shingle or sheathing temperature.

The biggest problem with building these unvented attics has been building codes. The codes do not like unvented roof assemblies. But changes are coming. First it was the 1997 edition of ASHRAE Fundamentals--it likes unvented roof assemblies (see "Vapor, Not Vents"). I predict that, in five years, the codes everywhere will have changed.


Composition asphalt shingles


These tend to absorb more solar radiation than other materials. The reflectance of conventional composition shingles ranges from 5 to 25 percent, depending on a shingle's color. Even white asphalt shingles reflect only about 25 percent of sunlight—low compared with the reflectances of white tile or unpainted standing-seam metal roof systems.

White composition shingles have low reflectance because of the granules' low pigment content, rough texture and black substrate. With current technology, it is possible to increase the solar reflectance of white composition shingles to 35 percent by increasing the granules' pigment amount.


Cold and Freezing Effects on Asphalt Shingles:

Storing shingles in freezing conditions increases the chances that a shingle will crack when being used if applied in cold weather, especially ridge cap shingles that break when bent. We used to cut those and then leave them inside on a radiator until needed.



Marcel

[rwand1]

Marcel

Thats very good article.

In the field I find this comment is right on: We've all seen attics that appear to be well vented, but ....

but if indoor humidity is high and humid indoor air leaks into the attic, the use of attic vents does not guarantee that attic moisture problems will not develop.

Seal, seal, seal.

Cheers,

[Brian A. MacNeish]

Originally Posted by rwand1

Marcel

but if indoor humidity is high and humid indoor air leaks into the attic, the use of attic vents does not guarantee that attic moisture problems will not develop.

Raymond:
This is the situation in which if you add more roof/attic ventilation, you may be allowing more air transfer between the house and the attic. The roof sysem may have been quite tight and not allowing air out of the attic but the new vents will. Allowing the existing air that has dropped moisture as condensation out of the attic now allows more house air with more moisture to rise into the attic by buoyancy (stack or chimney effect are other names for this phenomenon) through the loose ceiling air leaks. Thus more condensation and/or no drying.

I have consulted on 3-4 situations like this in my career. CMHC in their 1972 bookConservation of Energy in Housing mention this phenomenon showing up in their past research where venting increased or did nothing for some moisture condensation problems.



Cheers,

Seal, seal, seal. And save energy while reducing hidden vapour condensation,

[Brian A. MacNeish]

Originally Posted by mcyr

Everyone has an opinion, so here is mine for the one's that are interested in reading it. ha. ha.

The Hostile roof environment

Vapor, Not Vents

Although there clearly are potential benefits from attic vents in heating climates, there are also disadvantages: Vents can be prone to snow and rain entry that can wet the insulation, and cold air blowing through eave vents can degrade the thermal performance of attic insulation.

The Canadian R2000 program requires that all homes have solid wind deflectors at the edge of attics at the soffits. This prevents the loss of R value mentioned above.


Marcel

I have seen snow blow in through perforated soffit vents and about 11 feet up the air channel venting for a cathedral ceiling (put in by code) to end up in the main attic.

The picture is my attic 2 years ago.

[Barry Adair]

Originally Posted by dduffy

if those shingles failed because of poor ventilation I'll kiss everyones ***** here that even mentioned the possiblity......

That heat's cooked more than a few shingles

Times must be tough in AZ when you have to resort to interNACHInal solicitation on the BB