Asphalt roof single tab sealant bleed-out staining on a Maryland roof © InspectApedia Bob SissonsAsphalt Shingle Sealant or Laminated Tab Tarry Bleed-Out
Black tarry run-down stains on an asphalt shingle roof: opinions, theory, diagnosis

  • ASPHALT SHINGLE TARRY BLEED - CONTENTS: what caused the tarry run-down stains on the asphalt shingle roof shown in these photographs? An apparent bleed-down of single tab sealant. But was it factory material or something added by the roofer. Discussion, citations, opinions, diagnosis.
  • POST a QUESTION or READ FAQs about black run-down stains on asphalt roofing
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

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.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Black Tarry Bleed-out from Asphalt Roof Shingle Tab Sealant

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]

Asphalt roof single tab sealant bleed-out staining on a Maryland roof © InspectApedia Bob Sissons Asphalt roof single tab sealant bleed-out staining on a Maryland roof © InspectApedia Bob Sissons

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


Certainteed GrandManor® Brownstone Asphalt roof singles from the product catalogThanks for the photos, B.S. Indeed this is an interesting case that will be helpful to other inspectors.

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:

We put Certainteed on our house in 1998 when we built it. We had to re shingle it in 2005 and it should of been done sooner. Everyone around us was having trouble with certainteed and their warranty was a joke. I think we got about $1200.00 for a $10,000.00 job. They told us that we were suppose to reclue [Re-Glue - Ed] them with the $1200.00 and then they would stay in place. Google certained [CertainTeed - Ed] and you will find out about all their lawsuits. I think it was Timberlanes that we used the 2nd time and they seem good so far. - zmracing, 1/19/2012, Subject: RE: Good Shingles / Bad Shingles, West Central MN, original source tid=280835&DisplayType=flat&setCookie=1

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.

RE: Defective CertainTeed roof shingles / shangles
Just a followup. The problem is not just that the shingles didn't last the full 25 years. The problem is that the shingles have been documented to be defective from the manufacturer. There are cases where people's shingles are falling apart after 3 years on a 25 year shingle. This is a 100 year old company which we think unfortunately made a bad shingle and should replace the shingles on a roof. Wondering if anyone out there has had problems with this shingle and what they did about it.
 - posted by italiacook 8/25/05 at

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...

"I suggest you investigate the attic first. If you have low ventilation then the shingles will essentially bake in a very hot day i.e. temperatures exceeding 100F. If there is no air movement below the deck there is nothing to take the heat away. Shingles which are dark will absorb heat greater than lighter colour shingles and will heat up to 150 to 160 F under direct sunlight."

"Another source may be lack of curing from the plant originally. I have also seen this type of failure when the shingles had no chance to cure from the factory. In the period 2002 - 2004 if there was a lot of construction going on the shingles may not have cured from the factory. They are supposed to sit in yards for at least two months before being shipped out." - B.T. P.E. NTF: sent email query for citations 7/28/14 - Ed.

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

... the formation of gas blisters that made clear that such temperatures are not reached in-situ on a roof.

Reader Follow-up: CertainTeed Manufacturer Suggests Product Defect in GrandManor™ Shingles

I contacted CertainTeed and sent them a picture; this was their response:

... Thank you for sending a picture. That looks more like a defect. Feel free to call our roofing warranty department to start a claim. (800) 345-1145. ... - CertainTeed email to B.S. / W.S. July 2014

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


Continue reading at ASPHALT SHINGLE TEMPERATURES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




Suggested citation for this web page

ASPHALT SHINGLE TARRY BLEED at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman