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Cupping asphalt shingles:
This article series describes cupped asphalt roofing shingles and how to identify & explain the most-common asphalt roof shingle failures. These cupping shingle defects occur on both organic-mat and fiberglass-mat asphalt roof shingles, but are more common on organic mat asphalt shingle roofs.
We describe the difference between shingle cupping & shingle curling - which can be important in diagnosing the cause of early roof wear or damage. And we warn against walking on cupped shingle roofs. Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes.
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The roof shingles shown above are described by some inspectors as "curling" but as the shingle centers are clearly concave, I describe these as "cupped". In fact it's fair to say that both cupping and curling are present on this organic-mat asphalt shingle roof that is now fragile and at the end of its life. As you'll read in a moment, some even call this roof condition "clawing".
Watch out: Don't walk on this roof unless you're prepared to explain leaving a trail of broken shingle fragments to show where you stepped.
[Click to enlarge any image]
Definition of Asphalt Shingle Cupping
Cupping asphalt roof shingles, particularly on organic or felt-based asphalt shingles, are a normal wear pattern that shows up with shingle age.
Cupped asphalt shingles are show in our page top photo and in others on this page. In our photo (left) the top arrow in the photo at left points to the left side of a "cupped" area of this roof shingle. The shingle edges are also curled in these photos, which is part of this wear pattern.
This "normal" cupping or curling pattern will display shingles which are concave in their center, with the corners and possibly the three exposed shingle tab edges curled such that the very edge of the shingle curls downwards.
"Clawing" is also used to describe the appearance of asphalt roof shingle corners that curl down and under (photos above and below). Marshall et als (1999) observed:
Cupping and clawing results from asphalt shrinkage on the top and bottom surfaces of the shingles, respectively. The corners and edges of the shingles are prone to curling or cupping as the mat shrinks. Crazing of the shingle surfaces also results from asphalt shrinkage. Eventually, chunks of granules flake away from the mat leaving the asphalt coated mat exposed to the weather. - Marshall et als (1999)
Shingles in this condition are fragile and nearing end of life. In this condition, if someone walks on cupped shingles the raised cupped sections will break and can lead to early failure and leaks.
Our photo (left) shows that on the right-hand roof, virtually all of the shingles are cupped (red arrows & lines) and the shingles are also fish-mouthed. The staggering of fish mouthing on the roof is consistent with the location of shingle butt joints in successive courses.
Asphalt roof shingles as they wear either normally or in some cases at an accelerated (early failure) rate, often show one of the following wear signs, but as our photo at left illustrates (both cupping & curling) shingles can show any or all of these wear signs in combination as well.
Each of these asphalt roof shingle conditions is different in appearance and while all of them may indicate worn, old, or fragile roof coverings, their causes and prevention vary. In some of the photos of cupped roof shingles on this page, "fishmouthing" is also visible (see photo at page top). It is common for multiple wear signs to be present at once.
Cupped roof shingles are fragile: You should avoid walking on cupped-shingle roofs, particularly in cold weather (shingles are more likely to break).
As you can see in our photo (left) the raised fishmouth section of the cupped shingles is already cracking on its own. Stepping on this raised point (blue arrow) or on the raised area of the cupped shingle (red arrow) is likely to break it, converting a worn-out roof into one that is actively leaking.
Watch out: If we absolutely have to walk on such a roof, we would tiptoe carefully, avoiding stepping on the raised or cupped shingle sections, or if doing repairs, we would prop a ladder up off of the roof surface and work from that scaffold as is sometimes done with slate or other fragile roof surface repairs.
Walking on a cupped shingle roof can cause irreparable damage: Take this warning seriously: an old cupped asphalt shingle roof may not yet be leaking and could last several more years depending on its condition.
But we have seen cupped asphalt shingle roofs that had been destroyed by the "inspector" who walked all over the roof, breaking shingles everywhere he stepped, leaving a trail of damage and leading to the need for an immediate roof replacement. The roof would have needed replacement soon before the "inspection."
After the "inspection" the roof needed immediate replacement. we could actually see the "footprints of destruction" across the roof surface.
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Why is my new Roof cupping and it is only 2 weeks old? Yes Two weeks? - Joyce 11/28/11
Cupping of brand new roof shingles would be unusual. It might occur if shingles were installed over a wet roof deck or over an old layer of cupped, curled, or wet roof shingles.
Use the CONTACT link found at page top, left, or bottom to send us some sharp photos of the roof including some closeups and photos from a low angle that shows the cupping and we may be able to comment further.
I have a situation where my asphalt shingles have a 25 year material warranty and were installed 13 years ago. A large portion of the shingles are now cupping. The roof is a very simple hip roof with a single gable and one valley. Why are the shingles failing at approximately half of their life? Should the shingle manufacturer be held liable for the early product failure? Will they actually honor this material warranty? - Scott S. 3/12/12
Scott, shingle warranty claims are honored by manufacturers based in part on the manufacturer's assessment of the nature of the problem and their determination of whether the problem is due to faulty product or due to other problems such as a faulty installation or a structural or roof venting problem. You will want to contact the manufacturer and ask them to take a look at the roof, and
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