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ROOFING INSPECTION & REPAIR - home
AGE OF ROOFING
ASBESTOS & FIBER CEMENT ROOFING
ASPHALT ROOF SHINGLES - home
BEST ROOFING PRACTICES
BUILT UP ROOFS - home
CLAY TILE ROOFING - home
COLD WEATHER ROOF TROUBLE
DEBRIS STAINING on ROOFS
DECKS, ROOFTOP CONSTRUCTION
EPDM, RUBBER, PVC ROOFING
FIBER CEMENT ROOFING
FIBER-WOOD & FIBERBOARD ROOFING
FIRE RATINGS for ROOF SURFACES
FLASHING on BUILDINGS - home
FLAT ROOF MOISTURE & CONDENSATION
HAIL DAMAGED SHINGLES
HEAT TAPES & CABLES for ROOF ICE DAMS
HOT ROOF DESIGNS: UN-VENTED ROOFS
ICE DAM PREVENTION on ROOFS
ROOF DIAGNOSIS & REPAIR - home
LOW SLOPE ROOFING - home
MASONITE WOODRUF FIBERBOARD ROOFING
MEMBRANE & SINGLE PLY ROOFS
METAL ROOFING - home
MODIFIED BITUMEN ROOFING
NOISE CONTROL for ROOFS
PLASTIC ROOFING TYPES
PVC, EPDM, RUBBER ROOFING
ROLL ROOFING, ASPHALT
ROOF ARCHITECTURAL STYLES - PHOTOS
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF INSPECTION SAFETY & LIMITS
ROOF NOISE TRANSMISSION
ROOF REPLACEMENT SNAFUs
ROOF SLOPE DEFINITIONS
ROOFING CONTRACTOR SELECTION
ROOFING MATERIALS, Age, Types
SLATE ROOFING - home
SNOW GUARDS & SNOW BRAKES
STAIN DIAGNOSIS on ROOFS
STANDARDS for ROOFING
STRESS SKIN INSULATED PANELS
TEST LABS - ROOF SHINGLE
TILE ROOFING - home
TRUSS UPLIFT, ROOF
TRUSSES, FLOOR & ROOF
UNDERLAYMENT REQUIREMENTS on ROOFS
VENTILATION, ROOF SPECIFICATIONS - home
WALK-ON ROOF SURFACES
WARRANTIES for ROOF SHINGLES
WIND DAMAGE to ROOFS
WOOD SHAKE & SHINGLE ROOFING - home
Tarry black stains on asphalt shingle roofs: this article describes black rivulets of tar-like material observed on just a portion of the field of an asphalt shingle roof in the U.S. We discuss the possible and probable cause of these tar-stains and their effect (if any) on roof life, wind resistance.
This article also explores claims about asphalt shingle aging requirements before installation and it presents an observation methodology that can help sort out the causes of stains, irregularities, or damage & wear on roofs. Details are given for the properties of asphalt roofing shingles and the softening, melting, liquefying, and boiling point of the asphalt used in roofing products.
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Saw this on some really heavy duty shingles on a home in the Washington D.C. Metro area. They are bleeding asphalt out. The current owner is trying to tell us they are only 10 years old, I think they may be older but have nothing to go on. I will contribute some pictures to the cause if you can tell me a bit about these shingles.
[Click to enlarge any image]
We think these shingles may be Certainteed Grand Manor™ shingles. There are "bleeding shingles" on all sides of the building with no rhyme or reason. Certainteed sent us a standard "canned message" to "shingles stains", and we sent them the pictures, we will see if they get back to us with anything new/better. - B.S. (Professional Home Inspector), Maryland, USA
The image at left illustrates the Certainteed GrandManor™ roof shingle in the Brownstone color - which indeed looks very much like the close-up of the shingle type on the roof in your photographs. This is from a 2014 CertainTeed product brochure. That document points out that the GrandManor™ shingle line includes "StreakFighter™ ... a special manufacturing process used to protect ... shingles from streaking and discoloration caused by airborne algae."
These shingles will indeed include a self-adhesive strip on their under-side, intended for improving the wind uplift resistance to meet wind resistance described in our citation for this product and its brochure (below).
Your original note and photos might suggest that the bleed-down black rivulets are melting shingle tab sealant but I don't think so, since they do not appear consistently across the roof. While the manufacturing process for roof shingles can sometimes permit variation in product composition, that variation most likely across large production run quantities, not individual bundles of shingles.
If there were a product defect, more likely, given the quantity of tarry bleed-down, it would be in the sealant used to adhere the multiple plies of the shingle. Sweets Construction (cited below) points out that "The laminated tabs are firmly adhered in a special tough asphaltic cement. These fiber glass based shingles have self- sealing adhesive applied."
A web search for "Certainteed grand manor shingles sealant problems" (7/23/14) did not find other references to such complaints about shingle sealant problems though I did find a few comments about an older Owens Corning Duration™ shingle that used a continuous sealant strip that led to a concern for moisture trapping beneath shingles. That design has since changed.
Proposed Diagnosis for the Tarry Run-Down on CertainTeed GrandManor™ Shingles
In my OPINION, most likely the black tar-like run-down rivulets shown in your pictures above is not a shingle sealant-tab (for wind resistance) defect but rather a product failure involving the de-lamination of the multiple plies of the shingle or if someone attempted to repair the shingle, the subsequent bleed-out of roofing cement or even "tar" that some roofer added under the shingle tabs during original installation (or later). This may have been done for one of two reasons:
Shingle Lamination Failure: (most likely) If the multiple-laminations of shingles were failing an on-roof repair attempting to re-glue the shingles may have been attempted to extend the roof life. My research found this homeowner comment:
It's worth noting that in the same forum quoted above, other homeowners reported having no problems with CertainTeed Shingles. As I have suggested in this and other articles on shingle failures, the many variations in shingle production, storage, installation, and individual building details can explain why a shingle product's on-roof performance varies. Other gripes about CertainTeed shingles mention manufacturing defects but without enough detail. Most of the thread below was discussing CertainTeed Horizon shingle early failures and complaints about poor or very limited warranty coverage.
We won't know for sure about my guess unless occasion arises to cut apart some of the roof. But it would be indicative if the owners could tell us in what month the shingles were installed.
Sometimes when there are more than workers on a roof different workers follow different procedures and we can actually map who worked where. Maybe a novice blobbed on more cement in this area or maybe the roofer had a reason to attack just this area (such as shingles lifted and not "set" at the time of the roof installation along with an owner complaint).
And less likely,
Cold weather application: (less likely) While roofers install asphalt shingles in all temperatures, the popular saw that roofing is best performed above 40 degF. probably reflects the observation that in cold weather the self-sealing tabs may take longer to seal against wind uplift. Asphalt roof shingle tabs need an exposure of about 140 degF for 16 hours to seal properly against wind-uplift. - Cullen (1993).
Roofers will add extra cement under the tabs if roofing in cold weather, as an extra step in gluing down the tabs to avoid wind blow-off. The reasoning is that shingles installed in cold weather may take some time for the normal adhesive to melt and set the shingle tabs - sometimes months in some climates. I've fielded complaints of wind damage in just that situation.
If too-generous blobs of cement (or perhaps in this case something too much less viscous, even "tar" if that's what the roofer had at hand) were placed under the shingle tabs they might have melted and run out over the next or future hot summers.
I think this cold-weather extra-sealant theory is less likely because a close examination of your photos seems to show that the black tarry rivulets originate not from the shingle underside but from between two laminated shingle layers.
Tar-Like Shingle Run-Out Stains Diagnostic Questions
Reader follow-up: opinions about a requirement for shingle aging before installation?
The current owner doesn't know, they were that way when he got the roof.
However in asking the greater [home] inspector community, I got a response back that included the following...
We think that the worst of the bleeding shingles were added "about" 10 years ago. And that would line up with what the other group said. In any case we have strongly suggested that they get a formal "roof inspection" by a reputable roofer and see if we can get some more details.
These are really really heavy laminated 40-50 year shingles, and I think that the 'goo' between the laminations, close to your idea, never 'set' properly from the factory so when applied and got really HOT (attics around here can get to 150-160) they bleed. In any case, it is not "proper" and could/will affect life and more importantly, resale, so the current seller needs to 'address' this with my buyer.
Reply: patterns of of Asphalt Shingle bleed-down are diagnostic. Comments on other hypotheses:
Interesting. I'm surprised about the curing claim and will research it.
Attic temperatures & "baking shingles": About baking shingles suggested by B.T., it's hard to explain how rather uniform heating on a given roof slope produces asphalt or tar leakage only at some shingles if all were (most likely) produced in the same production run and arrived on the same pallet.
"Someone repaired a section of the roof": I'd caution that if the bleeding shingles were a patch or addition or repair on an older roof, the roofer may indeed have added extra sealant - but as the shingles in your photos look identical to their surrounding, non-bleeding neighbors this is a confounding theory.
I asked about the bleed-out pattern on the roof because it would be odd to find just a single bundle or two of asphalt shingles that were "not cured" while the rest of the roof shows none of this problem. That's a reason to think more carefully about this pattern.
Tar or other low-viscosity shingle tab add-on sealant? Also the thin-ness of the bleed out looks a lot like roofing tar to me.
It is certainly true that asphalt roofing products lose volatiles and become more brittle over time - we have published both explanation and research on this normal aging phenomenon. It would not explain the initial bleed-out we are discussing.
"Singles need curing time in the yard": About sitting in the yard, I don't want to ruffle feathers, so if you're willing you could ask B.T. for a citation on the "sit in yard" requirement - that would be valuable information to have. My own research on this question is presented just below.
Questioning the Claim of Required In-Storage Shingle Aging or Curing Before Installation Requirement Research
I (DF) researched asphalt shingle curing time for both scholarly research and manufacturer instructions but I was unable to find support for this view.
I've found a few references to "shingle curing" mostly relating (incorrectly) to the initial shingle granule loss on roofs. That claim is mistaken. The initial granule loss is the wash-down of poorly-adhered granules on shingles as delivered from the factory, appearing when the roof is new and washing down at the first few rainstorms. Granules are sprinkled on then rolled into the hot asphalt shingles - some of the top-most granules simply do not reach enough asphalt to bond firmly.
Curing is also discussed (as drying time) for some roof coating products.
"Curing" is also used as a synonym for normal asphalt shingle aging, such as in the Canadian Roofing Contractors publication I cite below. (In my opinion this article also contains an error when it claims that cracks in shingles do not affect their service life - this is certainly not true in a freezing climate).
Curing is also discussed by GAF in their application manual but NOT as asphalt shingle curing but rather as the curing of a substrate, such as concrete. The company does not cite a requirement for asphalt shingle post-manufacturing curing before use.
Nothing in the WARRANTIES for ROOF SHINGLES that I have reviewed cites a requirement for a shingle storage-curing time. - Bennett (2008), Behrdahl (2008).
Asphalt Shingle On-Roof Temperatures vs. Asphalt Shingle Manufacturing Temperatures
Details about temperatures of asphalt shingle manufacture & on-roof temperatures are at ASPHALT SHINGLE TEMPERATURES
Excerpts from that article are just below.
The manufacturing temperatures of asphalt shingles need to be high enough to permit the asphalt to penetrate the paper or fiberglass substrate, making them likely to be closer to the boiling (say 400-500° F) than the softening point 140° F to 205° F.
Indeed the manufacturers would not enjoy using asphalt at temperatures above 400° C (752° F) since that's its auto-ignition temperature. But the asphalt does have to be hot enough to flow into the shingle substrate. (The flash point for slow-curing liquid asphalt is around 150-225° F while an example MSDS for asphalt shingles gives a flash point of greater than 500° F. ) - IKO Production, Inc. (2012)
Similarly, TAMKO® asphalt shingle MSDS information gives the melting point of their asphalt shingles as > 200°F - well above normal on-roof temperatures. - TAMKO Shingle Product (2011)
Research on shingle durability tests asphalt shingles at temperatures typically up to a maximum of 160° F - well below the temperatures that occur during manufacture of the product.
At ASPHALT SHINGLE INSTALLATION we discuss shingle installation temperatures
and at BLISTERS on ASPHALT SHINGLES we discuss shingle manufacturing temperatures as part of the long debate about the blisters found on some new asphalt shingles. The blister topic convincingly argues that those blisters are a manufacturing artifact
Reader Follow-up: CertainTeed Manufacturer Suggests Product Defect in GrandManor™ Shingles
I contacted CertainTeed and sent them a picture; this was their response:
I will be forwarding the contact information to the listing agent for the property, to suggest the owner contact CertainTeed for the possibility of a warranty replacement. - W.S.
Thanks W.S. It is curious that the product defect shows up in the pattern that it does. Typically shingles are produced in such large quantities that a product defect in a production run would show up in all of the shingles in a given pallet of bundles of shingles and so would appear more consistently across a roof, perhaps varying by slope, pitch, sun exposure, color or other site variables but not so much varying within a given roof slope. Perhaps the product defect is one we've been documenting - that the shingles were delaminating and that someone tried an on-roof repair to "glue back down" the loosened plies.
Do keep us posted - working together we're smarter than any individual.
Asphalt Roof Shingle Research Citations
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