Thread: Melting window flashing?

I saw this for the 2nd time this week and I'm not sure what the exact cause is. This black goo looks like the peel-and-stick flashing they put around windows.

Both cases were about 5-year old homes at the south exposure.
Both homes were a fairly dark color and I assume this is the tar or mastic that was melting from the excess temperatures they are exposed to.

I wasn't really sure if this is some sort of factory defect or if the wrong kind of material was used.

I've only seen this twice and it seemed so peculiar... has anyone else ever seen this before? What did you say to the home buyer? Do you think the windows should be re-flashed?

Any comments or info would be appreciated!
-Stefan McGuire
Portland, Oregon

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Originally Posted by Stefan McGuire

I saw this for the 2nd time this week and I'm not sure what the exact cause is. This black goo looks like the peel-and-stick flashing they put around windows.


Both cases were about 5-year old homes at the south exposure.
Both homes were a fairly dark color and I assume this is the tar or mastic that was melting from the excess temperatures they are exposed to.

I wasn't really sure if this is some sort of factory defect or if the wrong kind of material was used.

I've only seen this twice and it seemed so peculiar... has anyone else ever seen this before? What did you say to the home buyer? Do you think the windows should be re-flashed?

Any comments or info would be appreciated!
-Stefan McGuire
Portland, Oregon

I would certainly recommend that they get someone out to find out just exactly what is going on. If this is some kind of sealant that was used instead of a proper flashing job then this may well be a failure in the making.

I have never seen the flashing product you mentioned melt and run like that but I have seen roofing tar used to "help" seal around window flanges.

Time to say "I do not know" and then tell your client that the siding will need to be removed to see what is going on. I would not even care to try and guess as to what it is or causing it. It never hurts to tell your client that you do not know or have a clue as why or what!

It does look like roofing tar.

I agree with Scott and Phillip. I've only seen that once, and it was on a house next to the house I was inspecting, so I didn't try to find out what was going on.

It does look like peel n stick membrane of some type to me.

I've seen a deck mfg using peel n stick over seams of plywood and/or the whole deck. The complaints I've heard from clients in hot areas where the deck is exposed to sun most of the day is their deck is buckling up in the hot sun, espcially when just semas have been taped over.

I've never seen windows melt out peel n stick but I imagine of the temps are hot enough and maybe Low E glass reflections are heating it up to it's melting point?

A few years ago I attended a window seminar and I do know those rubberized-asphalt flashings should not be in direct contact with flexible vinyl flashings or caulking and I believe the Anderson casements fit that discription with the molded vinyl is formed over the exterior window frame and molded with the nailing flange as one. I believe the asphalt compound can draw the plasticizers out of the vinyl causing the asphalt based compound to soften and flow which causes the vinyl to turn brittle.

At that time the rigid PVC (polyvinyl chloride) used in the window flanges that snap in were usually not a problem like you have with a double hung that has slots for the nailing flange to snap in. From the look of the sun exposure in the photos, it may be just those vinyl flanges reacting exposed to the solar and heat.

If they applied liquid flashing they are just stupid is as stupid does

Originally Posted by Joseph Ehrhardt

A few years ago I attended a window seminar and I do know those rubberized-asphalt flashings should not be in direct contact with flexible vinyl flashings or caulking and I believe the Anderson casements fit that discription with the molded vinyl is formed over the exterior window frame and molded with the nailing flange as one. I believe the asphalt compound can draw the plasticizers out of the vinyl causing the asphalt based compound to soften and flow which causes the vinyl to turn brittle.

At that time the rigid PVC (polyvinyl chloride) used in the window flanges that snap in were usually not a problem like you have with a double hung that has slots for the nailing flange to snap in. From the look of the sun exposure in the photos, it may be just those vinyl flanges reacting exposed to the solar and heat.

If they applied liquid flashing they are just stupid is as stupid does

I would like to hear more about not using buytl tape with vinyl window flanges. Can you direct me somewhere?

The Butyl is fine, its the asphalt base flashings that seem to be a problem, call each window manufacturer you deal with and arm your self with the flashing details and information of what to use or not, never assume, its all product knowledge and installing to the specifacations and save the information. Try to find installation guidlines for Tyvek stucco wrap from 20 years ago, how many staples and where to place them, plenty of links but the informations gone...things that make you go hmmm. all these window companies, flashing companies, paper barrier companies have some thing differant...CYA


Flashing Tapes with an Asphalt Base are

Fortifiber Fortiflash
Grace Vycor Plus
Protecto Wrap Flex
Typar Flashing RA
OSI TEQ -Flash

Flashing Tapes without Asphalt are

Grace Vycor Butyl
Dupont Straight Flash& Flex Wrap
3M Flashing tape
Fortifiber Moistop EZ-seal
Pella Flashing Tape
Venture Tape and Flashing
Protecto Wrap BT25XL
Typar Falshing BA

Stefan, your on to something and if you can get the invasive forensics on those windows or keep an ear to when someone opens those penetrations up, that would be good information to share.

I did some building investigation a few years ago on a indoor pool house that had black drips coming forom the knotty pine T&G cathedral ceiling. everyone thought it was the resin from the pine knots, After i opened it up, it ended up being the 8lb felt on the SIP's panels they used for insulation. they had recently change the duct work to a sock and the air was not circulating like the old and the chemicals with the humidity caused the oils of the asphalt paper to drip down as condensation

Thanks Joseph... good information.

This is an issue when the selected product cannot achieve the correct temperatures.
Fortiflash and Protectowrap were rated only to 150 degrees.

That siding in solar exposure, east, south and west will have temperatures in excess of 170 degrees.

Reentrant alcoves, metal roofs, and windows can increase the surface temperatures as well.

We are currently seeing this on many projects in the forensic applications. There were products available at the time such as Grace Vycor that were able to handle the 180 degree walls.

That was an interesting thread, I wonder if they ever found out what it was.

And your comment is intriguing, Edward. Welcome to the forum! I see it's your first post. 170 degrees? Wow. What kind of sidings get that hot? I imagine they must vary. Temps would vary geographically a lot, too, and by color. Hmmm.

This is sort of a tangent. But it's about flashing tape.

My dad had a guy install a skylight who'd never installed a skylight before. And he put new rubber roof down. He used Protectowrap (or a product from the same company, can't remember, something that was supposed to withstand exposure) around the edges of both, didn't bother to cover it with anything or even make sure the materials were compatible.

I said at the time, this is a really bad idea. Dad, you have to get someone to do this right.

The plastic has come loose and the tape disintegrated, but perhaps worst is its effect on the rubber, which it has caused to get all wavy, so water can easily get under it. I don't know what the guy used as adhesive under the rubber, but that ain't doing the trick, either.

It was my dad or his wife's idea to follow suit a couple years ago and "seal" the two square (leaky) skylights with the same tape.

The first two photos are from 2008, last three a couple months ago.

Some examples of what we are seeing.

The temperatures are taken at 78 degrees ambiant on east, west and south sides.

Remember that the east and west have the greatest solar gain in the summer, not the south.

Hi Edward,
I have been doing home inspections in the Denver Metro area for years. I have only seen this issue a few times, but I have never seen evidence of water penetration or problems from this, other than the obvious cosmetic ones. What are the problems that you see associated with this condition?

The main issue will be long term durability of the flashing systems is compromised at loss of adhesion. Even though leak is not occurring today, it will in the future as the membrane loses its function.

In areas of roofing, this may damage horizontal TPO or EPDM membranes.

Changes the characteristic of the building papers vapor control

Aesthetic issues as well.

Any idea why this isn't seen more often? The product has been around for years and used widely. Do you think it's happening a lot more than we can see? I wonder if it's a problem particularly when the flashing has been exposed to sun for a while before siding, and allowed to degrade. Or is it an issue with incompatible materials?

What a nightmare! I've used ProtectoWrap. I hope that doesn't happen.

In areas of roofing, this may damage horizontal TPO or EPDM membranes.


Do you have any photos representing the kind of problems you have seen with TPO and EPDM roofing?

Post #11 shows an example of damage to EPDM.

I see this fairly often with parapet flashing, basically the same stuff. Eventually there is not going to be any membrane left.
[ATTACH]P2240019.JPG[/ATTACH]

I wasn't sure whether Edward was referring to seams connecting sections of the material failing or something else, but the photos that you guys have are good ones. On those skylight photos, I have never seen a skylight flashed in like that. That looked like "doomed to fail" from the beginning, as you told your dad.

On the roof edging photos, that looks like it could just be excess pitch that has softened in the sun and run down rather than the adhesive bond failing. I have tugged on similar flashings in the past to see if they were tight and all were, but after this discussion, I think the real question is how secure these flashings and joints are when they have a hot sun beating down on them.

ProtectoWrap and ProtectoSeal 45 technical data sheets say their "operating temperature" is 240 F. Given the patchiness of this phenomenon, I wonder if it's a problem of people applying it around solvent based materials. Dad's silly handyman apparently caulked all around the tape edges with roofing caulk. Maybe people are using the flashing with the wrong kind of caulk, and heat then causes problems. Just an idea.

It's kind of crazy what the tape did to the edge of my dad's EPDM. It must have somehow caused it to expand. That's the only way those ripples could have been created.

Originally Posted by Kristi Silber

ProtectoWrap and ProtectoSeal 45 technical data sheets say their "operating temperature" is 240 F. Given the patchiness of this phenomenon, I wonder if it's a problem of people applying it around solvent based materials. Dad's silly handyman apparently caulked all around the tape edges with roofing caulk. Maybe people are using the flashing with the wrong kind of caulk, and heat then causes problems. Just an idea.

It's kind of crazy what the tape did to the edge of my dad's EPDM. It must have somehow caused it to expand. That's the only way those ripples could have been created.

That's why the proper sealants and adhesives are required to be used in conjunction with the material.

Put regular plastic roof cement on EPDM and other roofing material not compatible with regular plastic roof cement and one will deteriorate the other (usually the plastic roof cement will deteriorate the roofing material it is applied to or in contact with).

I suspect that the adhesive compound on the flashing tape is incompatible with the EPDM base materials.

The chemicals in the flashing tape probably migrated into the EPDM, swelling/expanding the EPDM, which caused the edge of the EPDM to wrinkle like that.

I suspect that the adhesive compound on the flashing tape is incompatible with the EPDM base materials.

The chemicals in the flashing tape probably migrated into the EPDM, swelling/expanding the EPDM, which caused the edge of the EPDM to wrinkle like that.

I'm not sure the tape itself is the problem. I'm pretty sure it's Protecto Seal 45, a butyl hybrid. There's nothing in the specs saying it's incompatible with rubber roof, but they are both incompatible with asphalt-based products, with which the tape was thoroughly caulked. Who knows what exactly happens chemically once they all interact?

Looking closely, it does appear that the remains of the tape on my dad's roof look quite similar to some of the older encrusted drips on the siding.

(Sorry, this is off-topic, but is anybody familiar with the greenish adhesive under the rubber, where I've pulled the corner up? Another photo of it below, when it was newly applied.)

Originally Posted by Kristi Silber

I'm not sure the tape itself is the problem. I'm pretty sure it's Protecto Seal 45, a butyl hybrid. There's nothing in the specs saying it's incompatible with rubber roof,

Which is a compatibility problem between the tape and the roof material. By the way, just to clarify "the tape" includes the 'top layer, the intermediate layer, and the adhesive layer' of materials which make up "the tape".

Thus, if "the tape" was not applied on the EPDM, there would not be a compatibility problem ... right?

Which means, in that application, "the tape" itself is the problem ... the EPDM by itself is not a problem ... right?

Originally Posted by Jerry Peck

Which is a compatibility problem between the tape and the roof material. Which roof material? The roll roofing or the rubber? By the way, just to clarify "the tape" includes the 'top layer, the intermediate layer, and the adhesive layer' of materials which make up "the tape". How does that clarify anything?

Thus, if "the tape" was not applied on the EPDM, there would not be a compatibility problem ... right? Well duh! Not between the tape and rubber anyway. But if you remove the tape and keep the solvent-based caulk, you could still have trouble.
Which means, in that application, "the tape" itself is the problem ... the EPDM by itself is not a problem ... right?

No! If my hypothesis is correct, it's the caulk, not the tape, that's the problem. People are using solvent-based caulks with flashing tape, and they are reacting chemically, especially when heated.

Originally Posted by Kristi Silber

No! If my hypothesis is correct, it's the caulk, not the tape, that's the problem. People are using solvent-based caulks with flashing tape, and they are reacting chemically, especially when heated.

Ahh... ¿Comprende? for your photo, but it is the tape on the others, correct?

In both of Edward's photos in post #12 you can see caulk squeezing out from under the bottom nailing flange, and on one of them you can see caulk at the bottom of the taped area. I'm saying that may have is part of the problem. It's like the caulk is "activating" the stuff in the tape, allowing it to melt. Or perhaps dissolving the matrix holding everything in place even when heated.

Another possible issue with both is the nailing flange itself, since the tape isn't supposed to be used with PVC-based nailing flanges. But that wouldn't be the issue with Benjamin's parapet flashing, and I don't think that's part of the dripping problem. (Not that I've studied it in great detail, or really know jack about any of this chemical compatibility stuff...I'm just putting together the evidence.)

Originally Posted by Kristi Silber

In both of Edward's photos in post #12 you can see caulk squeezing out from under the bottom nailing flange,

That's on the cover side, that should not do any harm there.

and on one of them you can see caulk at the bottom of the taped area.

I believe those areas are actually where the adhesive was chipped off, leaving that discolored area.

I'm saying that may have is part of the problem. It's like the caulk is "activating" the stuff in the tape, allowing it to melt. Or perhaps dissolving the matrix holding everything in place even when heated.

Not disagreeing with that IF the caulk is in contact with the adhesive, but I think it was not, at least in those photos.

Quote:

Originally Posted by Kristi Silber
In both of Edward's photos in post #12 you can see caulk squeezing out from under the bottom nailing flange,

That's on the cover side, that should not do any harm there. The part you can see is, anyway...under the flange it could contact the edge. But maybe it isn't a problem there.

Quote:

and on one of them you can see caulk at the bottom of the taped area.

I believe those areas are actually where the adhesive was chipped off, leaving that discolored area. Well, adhesive or caulk, it could be just as problematic. Or what adhesive are you talking about?


Quote:

I'm saying that may have is part of the problem. It's like the caulk is "activating" the stuff in the tape, allowing it to melt. Or perhaps dissolving the matrix holding everything in place even when heated.

Not disagreeing with that IF the caulk is in contact with the adhesive, but I think it was not, at least in those photos.

OK. You can't tell where there was caulk/adhesive/whatever under the tape. You don't know what they do when they are in contact. All I'm doing is positing a hypothesis, and based on the information we have there is no way for you to disprove it. I could very well be wrong, but I haven't heard you offering a better explanation. This sort of tape has probably been used to flash windows and doors in 10s of thousands of homes, yet the dripping is an uncommon problem...so there must be some third factor besides heat and tape. Doesn't that make sense? My dad's roof was caulked around the tape (not under it) with solvent-based caulk, and the tape ended up dissolving weirdly, so there's some evidence that the solvent-based stuff is an issue.

I stumbled on some information about this phenomenon. See page 7, here.

"Most sealants on the market contain plasticizers. Certain plasticizers commonly found in caulk and sealant have the effect of liquefying the asphalt portion of asphalt self-adhering flashings and film/asphalt/film laminated flashing. These plasticizers can also be present in other flexible membranes such as EPDM and flexible plasticized PVC (sheet vinyl), as well as a variety of other building materials."

The green substance looks like contact cement, that is made for EPDM. EPDM manufactures have their own pallet of accesories that have been aproved for use with their product, no need to experiment with using unaproved materials.

Originally Posted by Kristi Silber

That was an interesting thread, I wonder if they ever found out what it was.

And your comment is intriguing, Edward. Welcome to the forum! I see it's your first post. 170 degrees? Wow. What kind of sidings get that hot? I imagine they must vary. Temps would vary geographically a lot, too, and by color. Hmmm.

This is sort of a tangent. But it's about flashing tape.

My dad had a guy install a skylight who'd never installed a skylight before. And he put new rubber roof down. He used Protectowrap (or a product from the same company, can't remember, something that was supposed to withstand exposure) around the edges of both, didn't bother to cover it with anything or even make sure the materials were compatible.

I said at the time, this is a really bad idea. Dad, you have to get someone to do this right.

The plastic has come loose and the tape disintegrated, but perhaps worst is its effect on the rubber, which it has caused to get all wavy, so water can easily get under it. I don't know what the guy used as adhesive under the rubber, but that ain't doing the trick, either.

It was my dad or his wife's idea to follow suit a couple years ago and "seal" the two square (leaky) skylights with the same tape.

The first two photos are from 2008, last three a couple months ago.

IS that a ballasted cable wire or heat tape with railroad spikes ????????????????

The common denominators in the two photos in post #12 are the Weathermate Brand product which has been inappropriately been put in environmental contact with asphaltic based flashing tapes. Dow's product requires use of buytl rubber not asphaltic or bitumen.

Mixing and matching incompatible materials incompatible with proprietary system componants, products or approved, compatable substitutions.

Incompatible materials.

Chemistry, environment and gravity evidences the rest.

I revived this thread to address the dripping problem, but I'm plenty happy to talk about my dad's roof!

Originally Posted by Phil Brody

The green substance looks like contact cement, that is made for EPDM. EPDM manufactures have their own pallet of accesories that have been aproved for use with their product, no need to experiment with using unaproved materials.

I wonder why it's not sticking well. I got up there yesterday and realized it looks like the handy man that did the work apparently put the new layer of EPDM over the old, which is a bit of a relief just to know there's a protecting layer under there. Now I understand why it's not leaking as badly as I would expect.

Originally Posted by Phil Brody

IS that a ballasted cable wire or heat tape with railroad spikes ????????????????

It is for heat to deal with ice dams. The RR spikes holding it down always bothered me, though I don't really know why. Was wondering if someone here would notice that and comment...so please do.

Found out yesterday the tape around the edges of the rubber is Jeld-Wen, but haven't been able to find out much about it, like whether it is made to withstand exposure (which I doubt) or what it's made of, and whether it's compatible with EPDM.

Originally Posted by H.G. Watson, Sr.

The common denominators in the two photos in post #12 are the Weathermate Brand product which has been inappropriately been put in environmental contact with asphaltic based flashing tapes. Dow's product requires use of buytl rubber not asphaltic or bitumen.

Mixing and matching incompatible materials incompatible with proprietary system componants, products or approved, compatable substitutions.

Incompatible materials.

Chemistry, environment and gravity evidences the rest.

Couldn't find support for the Weathermate incompatibility; do you have a link? But yes, mixing incompatible materials seems to be the problem behind the drips.

I saw a similar, but not as goopey, situation on a stucco house with newer windows. Black tar-like substance dripped down from the windows onto the stucco. I told them I did not know what it is, but suspected the window installation/flashing as a likely culprit. Contact window installer for further evaluation. This may occur regularly after rains. The staining is aesthetically unappealing.