Asphalt shingle cracks due to thermal splitting & defective product: illustration, cause, warranty, repairs.

This document tells readers how to identify & explain asphalt shingle cracking or thermal splitting, what causes shingle cracks or splits, and how to distinguish this product failure (which may be entitled to a warranty or class action claim) from other roofing product failures or defects.

Fiberglass Shingle Cracks: Thermal Splitting Asphalt Shingle Crack & Tear Failures Described & Explained

Fiberglass-based Asphalt Roof Shingle Cracking/Tearing/Splitting Failures

"Thermal splitting," or "cracking" which in fact is in most cases actually a tearing of the shingles is considered by experts to be the principal current problem with fiberglass-based shingles.

We prefer the terms shingle tearing as a most accurate description of what's probably happening. Originally observed on the lightest-weight (15-year life) shingles this problem has now been found across all shingle styles, weights (life ratings), and we suspect, probably across most or all manufacturers of this type of product.

The thermal expansion of defective asphalt shingle product (common in the U.S. across many manufacturers in the early 1990's) followed by thermal contraction when cool weather approached, explained the tear shown in the shingle in our photograph just above.

See THERMAL EXPANSION of MATERIALS for a table of the coefficient of expansion of common building materials. We have not found a source defining the coefficient of thermal expansion of asphalt roof shingles - Contact Us if you can provide that information.

Does Thermal Splitting or Shingle Cracking Tearing Occur only in 3-Tab Asphalt Shingle Roofs?

No. Thermal splitting or tears occur in both conventional 3-tab shingles (photo above) and also in laminated asphalt shingle roofs.

Our photo above of thermal split/tear damage to a laminated asphalt shingle roof was provided by ASHI Home inspector Steve Mauer.

This unfortunate roof, inspected by Mr. Mauer in 2009, also suffered from granule loss (below-right) that in our OPINION looked like a defective product.

The same roof also included a damaged shingle that looked like a cracking and granule loss problem combined, but we think this was a shingle splice created at the factory during production - a bad individual shingle that is sometimes created when ends of shingle production substrate are spliced together.

See SPLICE DEFECTS on ASPHALT SHINGLES

What Does Shingle Cracking or Shingle Splitting Look like?

Watch out: : as we warn at ASPHALT SHINGLE FAILURE TYPES if conditions prevented the home inspector from direct access onto the roof or at least a look from a ladder set against the roof edge, shingle damage, cracks, and splits such as that shown in own photo below could have been difficult or even impossible to spot.

Inspecting the roof from the ground, even with good binoculars, can't show all roof damage types and conditions.

We have observed a variety of torn or split asphalt roof shingles, illustrated by our photographs below. (Click to enlarge any image.)

• Horizontal or vertical tears across multiple 3-tab shingles - shown above

• Horizontal, vertical, and diagonal tears across multiple strip-type shingles - shown above

• Horizontal, vertical, diagonal, and corner tears across multiple laminate-type shingles - shown above

Horizontal Cracks & Splits in Asphalt Shingles

Both thermal splitting and other shingle cracks and splits can also occur in a horizontal pattern as we illustrate in our photographs below.

The horizontal cracking occurring in these fiberglass-based asphalt shingles resulted in complete loss of some of the shingles from the roof surface.

The silicone caulk was placed by the owner during an attempt to "re-glue" the lost shingle tabs. But using our pen we pointed out additional horizontal cracks and tears developing in the next course of shingles just below. From a the ground the lost shingles looked like an isolated problem.

An on-roof inspection told a different story.

Both horizontal and diagonal or vertical tearing may occur in the same roof as we illustrate in our photo at left (Click to enlarge).

What is the Cause of Thermal Splitting Cracks in Fiberglass-based Asphalt Roof Shingles?

Our photos above demonstrate two classic thermal split patterns in fiberglass based asphalt shingles: vertical splits running straight up the roof (above left) and diagnoal splits following butt joints (below).

• It's possible that shingles made by some manufacturers do not meet the ASTM Standards for tear resistance.


• Even where shingles meet the Standards, it's possible that the standards themselves were defective. In particular, for a time the asphalt roof shingle standards combined these concerns:
  • A thin fiberglass mat was permitted as the shingle substrate, lacking adequate tear resistance
  • The wind uplift prevention bonding adhesive was too strong, causing the shingles to bond into nearly a single continuous surface that lacked adequate movement to respond to significant changes in temperature without tearing the bound surface
  
  
• In any case, Fiberglass mat may lack adequate tear resistance


• Self-sealing tabs on shingle backs may glue shingles together with too much strength, causing the roof covering to form a single large membrane which cannot accommodate large temperature changes. This explanation was discovered across the asphalt shingle industry.


• Reduced total amount of asphalt in thin fiberglass mats might become brittle after exposure to heat and sunlight


• Temperature swings probably contribute to the onset and extent of tearing, and we'd expect worse tearing where temperature swings are more extreme such as in Northern climates.


• Nailing or placement pattern of shingles: "laddering" vs. "staggered." On laminate and strip type shingles we have inspected roofs on which damage is found occurring at the corners of shingles rather than in the middle of the shingle material. It appears that as temperatures dropped and the glued-together-roof-membrane cools and contracts, the natural point at which movement occurs is where shingles are end-butted together.
  
  When the pattern of end-butts is laddered rather than staggered up the roof we have found corners tearing off of shingles following the laddering pattern exactly. (Laddering is not a recommended installation pattern according to NRCA and ARMA publications nor according to instructions from some manufacturers.)
  
  Laddering alone cannot be blamed for this failure however, as we have seen similar shingle tearing following a staggered end-butt pattern up other roofs. However laddering may indeed create a more localized natural point of separation on a roof, causing most of the movement to occur in a smaller area when the roof material contracts with cooling.

Splits or Cracking in Organic Asphalt Shingles

Organic mat asphalt shingles also may show cracking and accompanying granule loss. Defective asphalt shingle products of either organic or fiberglass based shingles may experience several failures including cracking, tearing, granule loss, blistering, etc. So, splits or cracks can occur in both organic-mat based and fiberglass-mat based asphalt roof shingles.

See ORGANIC FELT SHINGLE NORMAL WEAR for details about normal wear splits or cracks and granule loss in organic roof shingles.

Also see ORGANIC FELT SHINGLE DEFECTS for other wear signs on organic mat asphalt shingles.

But thermal splitting is particularly a problem with fiberglass mat based asphalt roof shingles. The catastrophic early shingle splitting failures like the ones illustrated earlier in this article were principally a problem of lightweight, fiberglass-mat based asphalt roof shingles made during the period discussed above. Roughly, from 1992 - 1997.

Nevertheless, fine cracks through roof shingles, regardless of cause, mean accelerating wear rate and on a roof like the one shown at left, the roof needs replacement.

Cracking due to cold weather installation & bending ridge or hip cap shingles:

see RIDGE & HIP CAP SHINGLES for additional discussion of distinguishing cracking wear failures from other types of shingle failures.

Also see ASPHALT SHINGLE PROPERTIES and

see

• CHOOSING AN ASPHALT SHINGLE: ORGANIC VS. FIBERGLASS, [PDF] Ted Cushman, The Journal of Light Construction, May 1993 for more about the debate around the advantages and disadvantages of organic mat asphalt shingles vs. fiberglass mat-based asphalt roof shingles.

Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-08-21 by Steven thierath If shingles are flipped by wind and then creased can that cause horizontal cracking?

Question wouldn't a 3 tab shingle that has been blown by the wind and flipped completely back onto to the shingle above it then layed back and that has a crease in it now where it bent at the other shingle , be very similar if not exact same as what horizontal thermal cracking would look like ?

like in the pictures I've added these seem.like they could be from theal cracking horizontally or the wind flipping them back creasing them and then laying back down as well as the other pic would the wind not blow the shingle up taking the nail with it amd then when laying back down the nail does not retirn to zhe hole iz came out of and remains? popped

Reply by InspectApedia Publisher (mod) Yes ultimately but it's not thermal splitting it's mechanical damage

@Steven thierath,

Thermal splitting and cracking marks

- are not confined to straight lines
- are not confined to positions parallel to the upper or lower edges of shingles
- don't show shingle granule loss characteristic of having bent a shingle back and forth

Both types of shingle damage (or other causes of a shingle tab being bent or lifted) can ultimately result in an actual open crack, and both are reductions in the remaining life of the roof - though the extent of impact varies from case to case.

 

On 2022-10-24 by BARRY GARDNER - Roof worn out after 17 years

@InspectApedia-911,
17 yrs old spider cranked and disintergrated granular gutters full
Saint john nb 2848 westfield rd e2m 6r8
Been like this for many years suposed to be 25 yr home hardware product
Condition getting worse by the year
Roof was brand new trusses and ply wood and shingles
Thanks Barry

Reply by InspectApedia (Editor) (mod)

@BARRY GARDNER,

I agree that the roof is shot. Possibly already leaking (check in the attic).

I see fishouthing in the upper roof, and extensive cracking, granule loss, and water absorption in the shingles on the lower roof.

I recommend getting going asap on replacement. You can contact the manufacturer about a claim and *might* get a small amount -shingle cost, pro-rated by age vs. warranty period, provided an tnspector doesn't find installation or roof venting errors.

Keep in mind that attic venting can also affect roof life - so check that too.

Daniel

On 2022-09-03 by Ike - If my shingles are cracked throughout do I need a new roof?

19 yrs asphalt shingles have vertical crack’s thru out.best to get a new asphalt roof put on?

Reply by InspectApedia-911 (mod)

@Ike,

Most likely, yes. Please post some photos, at least one, you can post one photo per comment. I'd like to see the condition of the roof and to know its location, country city state or province.

Then we may be able to make more specific suggestions.

 

Asphalt shingles not lasting in Minnesota

Just sent a ton of pictures of my roof to insurance company. Shingles are cracked all over the place.

Insurance company won’t cover saying it’s from heat and cold. Roof is only 6 years old. Like everyone else, why would you put shingles on a house that can’t withstand the weather. Minnesota - On 2020-11-20 by Kathy Limanen -

Reply by (mod) -

That sounds like a product failure, perhaps not covered by your homeowners policy but I'd need to see some diagnostic photos.

My Idaho roof asphalt shingles are cracked - should I hire an Inspector

Wow, want a great article. I live in Idaho and have a 10 year roof that is suppose to be a 50year roof according to the manufacture. We had a hail storm and I had a roofer inspect it for damage.

I had no hail damage but I have cracks all over. Some are 6 feet going up the roof at a 45 degree angle and others much shorter.

My builder looked at it and was floored. Now I need to convince the mfg and distributed that this was defective material. This article really helps. Sound I hirer a building inspector? - On 2018-08-25 by Ken Martin -

Reply by mod

Yes it's worth having an accurate expert diagnosis of your roof and advice on

- the extent of damage and the risk of roof leaks

- what repairs are needed, and when

Any recourse when my roof failure started thermal splitting after the warranty period?

This problem started on my good about 20 years ago and is probably past the warranty period. I filed a insurance claim when it first occurred. I was told it wasn't covered. Is there any recourse? - On 2016-12-19 by Del Gonzales -

Reply- by (mod) -

I'm surprised to hear about thermal splitting on a 2009 roof, but I guess it's possible. Use the page top or bottom CONTACT link to send me some sharp photos of the damage and we can comment further.

But no, if no damage was visible and documented before the roof warranty expired I'm doubtful that the manufacturer will have an obligation.

My 35-year-life asphalt shingles are splitting after 7 years

Looks just like the problem I am having with my 7-year old roof built using 35 yr. asphalt/fiberglass shingles.

Now how to get the shingle manufacturer to admit they have a shingle quality problem .
If their shingles can not stand Alberta's climate , why are they selling them here.

I was in business for 35 years and if I sold defective product I was on the hook for old product removal , new product
and new product instalation so why not them ? - On 2016-07-25 by Derek Hoyle

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• ASPHALT SHINGLE FAILURE TYPES
• ASPHALT SHINGLE LIFE / WEAR FACTORS
• ASPHALT SHINGLES on LOW SLOPE ROOFS
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