Thread: Bubbles in EPDM

I don't see much EPDM - I assume that being EPDM small sections of membrane are easily replaced, but why the bubbling? Also, is the attachment method at the metal penetration correct?

Thanks

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Anyone?

Normally I'd say the bubbles are generally due to moisture underneath the membrane but your third photo has me stumped. I was waiting for someone else to step to the plate.

The rake shot is from pushing sealant into the Epdm after a call back or a final inspection once the roof was completed.

The bubbles could be from either too much adhesive or they used RTR (Rubber to rubber)instead of a bonding adhesive.

Another issue that could be added is regardless of the type or method or adhesive used the flashing should have been cleaned/replaced or treated.

That rust is spreading across the flashing and is breaking down the adhesive.Nothing sticks to rust and if it does it won't for long once the rust starts to spread over the flashing.

Water/moisture/even air will do that if trapped in when it is sealed down.

The water/moisture/air expands when it gets hot, and as the sealant gets hot it allows the expanding water/moisture/air to rise and migrate toward the area with least resistance trying to keep it down, i.e., toward the edges. At the edges it is kind of like blowing a bubble with bubble gum, it will grow and grown until it pops a hole in it and then the expanding water/moisture/air escapes out.

Had it on a townhouse development years ago in Miami-Dade county, the roofer who replaced the roofs kept working through a light rain, and a year or so later there were those bubbles being blown all around the built up roofs. Roofer ended up replacing all those roofs a second time - at his cost.

Pic 1 - can't tell squat, looks generally Ok
Pic 2 - poor detailing, either didn't heat enough, underside had junk/dirt underneath that prevented good adhesion, or guy didn't go over the joint with a detail torch
Pic 3 - over torching, I did it a few times as a rookie, then got tired of getting yelled at
Hope that helps

I only seen bubbles around the flashing.,is there bubbles on the entire roof ?

The rest of the roof is fine, the bubbles are all over flashing.

Originally Posted by Michael Thomas

The rest of the roof is fine, the bubbles are all over flashing.

Then IMO its a rust issue.The rust is breaking down the adhesive as it spreads across the metal creating the pockets.Not that it matters but I think those bubbles lower considerably at night or in the cooler months.

Originally Posted by Markus Keller

over torching,

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Epdm ?

Originally Posted by Roofmaster 417

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Epdm ?

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ERA - EPDM Roofing Association Home
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Originally Posted by Billy Stephens

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ERA - EPDM Roofing Association Home
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I was not questioning what Epdm was.Hahahahahaha.,Geez.,hopefully if I were posting advice and information about Epdm on a post specifically for Epdm then.,well never mind.

I quoted another posters reply related to a torch.I finished a massive Epdm roof a couple days ago and more installations than I can remember and unless the installation procedure has changed dramatically since that time then a torch is the last thing you would want near Epdm.I was just trying to be subtle.

Originally Posted by Roofmaster 417

I was not questioning what Epdm was.Hahahahahaha.,Geez.,hopefully if I were posting advice and information about Epdm on a post specifically for Epdm then.,well never mind.

I quoted another posters reply related to a torch.I finished a massive Epdm roof a couple days ago and more installations than I can remember and unless the installation procedure has changed dramatically since that time then a torch is the last thing you would want near Epdm.I was just trying to be subtle.

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Sorry,

Just just passing through.
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Is that bituminous tape at the seam, and underneath the edge? Perhaps that's the problem.

Originally Posted by Billy Stephens

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Sorry,

Just just passing through.
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No worries Billy.,I apologize if I seemed arrogant or rude.

From the pics, especially Pic 2 and 3 doesn't look like a straight stick down roof to me. Could be wrong of course but looks like somebody had a torch up there.

Originally Posted by Markus Keller

Pic 3 - over torching, I did it a few times as a rookie, then got tired of getting yelled at

Over-torching! Hadn't considered that one. Give the man a cigar!

Originally Posted by Eric Barker

Over-torching! Hadn't considered that one. Give the man a cigar!

You cannot use a torch on Epdm.,NO FIRE !!!!!.,Maybe torching the entire building,,,Epdm CANNOT BE TORCHED !!!!!

to me it looks like the wrong product was used to flash in around that vent. with EPDM you must use their products in cluding the glue. mix of materials can cause this kind of bubbling. we had to repair a roof that had this same issue, turns out some one used rubber pool liner and EDPM glue
and the regular rubber reacted to the glue. then they called us to repair.

Mike

Originally Posted by Michael Thomas

I don't see much EPDM - I assume that being EPDM small sections of membrane are easily replaced, but why the bubbling? Also, is the attachment method at the metal penetration correct?

Thanks

Originally Posted by Roofmaster 417

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Then IMO its a rust issue.The rust is breaking down the adhesive as it spreads across the metal creating the pockets.Not that it matters but I think those bubbles lower considerably at night or in the cooler months.

.*see attached lightened photo showing Rust on Flashing.
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Michael, can you clarify what the flashing material is? I can see the bit of rust around the vent, but the rest of the flashing looks more like an adhesive tape. Is there metal under it?

In order for something to rust, it usually has to have oxygen and water. As far as I know, the reaction doesn't release any gasses, so where would the bubbles come from?

Seems like this could be a situation similar to the one about "melting" flashing in this thread.

Originally Posted by Roofmaster 417

You cannot use a torch on Epdm.,NO FIRE !!!!!.,Maybe torching the entire building,,,Epdm CANNOT BE TORCHED !!!!!

Sorry to be exacting but you can torch EPDM and I'll wager that is what was done. I agree with your indirect point that you should not torch it.

I'm still sticking with air/moisture/water blisters.

Not jagged enough to be rust, to 'expanding bubble' shaped for that.

I'm not buying the torch at all.

I think it is old fashioned sun generated heat acting on trapped air/moisture/water blisters.

Originally Posted by Eric Barker

Sorry to be exacting but you can torch EPDM and I'll wager that is what was done. I agree with your indirect point that you should not torch it.

There are 4 ways to install Epdm and a torch is not included in the installation.I have been installing Epdm roofs for 12 years and have been involed with the application even longer.

Fully adhered,ballasted,mechanically anchored or battened in the seam.

The picture tells the tale.The flashing has rust around the back and pretty sure it is around the entire flashing.Before the new roof was installed the flashing should have been replaced.Even though the material is sealed with an adhesive to the flashing if the rust was there prior to the reroof it will continue to spread.

The adhesive has no rust control additives so of course the rust will continue to spread.Even though the metal has no direct airflow does not mean it will stop rusting.

It is not a scientific phenomenon.The Epdm was attached to an unsuitable surface.,unsuitable meaning solid and defect free surface for adhesive to adhere to.

It maybe a combined error of not using the correct adhesive.,It is possible that the installer used RTR to try to bond the Epdm to a rusty furnace flashing.But that would not have held up for very long.

It is also a good possibility that the material was not brushed/rolled out after the adhesive was applied eliminating any bubbles under the material.

I don't understand why you think there's metal flashing under all the bubbly parts. In the third photo there's the metal pipe flashing, but that's on top of the rubber on the near side. The second photo shows drip edge, but you can see where a seam is in the upper right; it's under the rubber but on top of the drip edge. Why would there be strips of metal flashing in all the bubbly spots shown? Adhesive tape, on the other hand, would make perfect sense (if that were the product meant for the job!), and that's what it looks like.

Originally Posted by Roofmaster 417

It is also a good possibility that the material was not brushed/rolled out after the adhesive was applied eliminating any bubbles under the material.

And that air expands when it gets hot, stretches the EPDM out, allowing more air in the bubble, and allowing condensation, and the next heating cycle makes the bubble worse, and the next heating cycle ... Ad infinitum.

Originally Posted by Jerry Peck

And that air expands when it gets hot, stretches the EPDM out, allowing more air in the bubble, and allowing condensation, and the next heating cycle makes the bubble worse, and the next heating cycle ... Ad infinitum.

Hot air in a bubble, stretching it out, is under pressure and if anything will leave the bubble rather than let air in. How would it get in, anyway?

I agree moisture may be the problem. It's possible that water droplets turning to steam could cause bubbles, but the roof would have to get to 212 F.

Originally Posted by Kristi Silber

Hot air in a bubble, stretching it out, is under pressure and if anything will leave the bubble rather than let air in. How would it get in, anyway?

It starts with air in, from bubbles not rolled out, and sometimes more air gets in through a seam that seam tape is covering.

Heat the air and it expands, leaving the bubble stretched. Heat the air again and the bubble expands more. Repeat for each heating cycle.

When the bubble gets large enough, condensation can collect inside the bubble, so the next time the heating cycle is heating and expanding both air and moisture.

I agree moisture may be the problem. It's possible that water droplets turning to steam could cause bubbles, but the roof would have to get to 212 F.

Doesn't have to turn to steam, just heat water and it expands, heat air with moisture in it and it expands, heat dry air and it still expands.

After I zoomed and zoomed and zoomed again I think I am seeing what you are seeing now Kristi.,

That is a super small non existent flashing around the pipe.The flashing should extend as far out to the edge of the bubbled area.

That is what was misleading me I have never seen a pipe flashing that had material under it rather than over the flashing closing the seam.

My fault.Other than an incorrect flashing the problem is most definately from not rolling out the material.

The flashing around the pipe should extend to the red line.

There should be 6"-10" strips over the flashing creating a secondary flashing.

I'm guessing what we're seeing is the "downslope" edge of the vent flashing (I know, it's a fairly flat roof, but I'm trying to think what the installer was thinking). There's the EPDM at the bottom, then a bib around the pipe above your red line, then the vent. The upper main section of rubber we're seeing lapped down the sides, over everything. Pretty much like you'd do on a shingled roof.

I agree, the metal flashing is way too short.

I don't know about the rolling out theory. The bubbles are all associated with the tape (what I think Michael is calling the flashing). The tape shouldn't really get all gooey like that, should it?

Using the wrong products together could result in a gas-producing chemical reaction. The heat could have something to do with it, too. It's just an idea. There could be moisture or bitty air pockets, who knows? but why that alone would cause problems only where the tape is, I don't know.

Jerry, what you are saying simply doesn't make sense in terms of physics. Yes, water expands when heated, but not much - certainly not enough to make a large bubble. Air expands, but a given volume of air will exert the same pressure at the same temperature no matter how many times it's heated, and if air can get in, it can get out. If each cycle of expansion and contraction makes the membrane weaker, that's different since the pressure needed to expand it would be less, but still the air will expand only so much as it heats.

When the bubble gets large enough, condensation can collect inside the bubble, so the next time the heating cycle is heating and expanding both air and moisture.

Why would the bubble size have anything to do with moisture getting in, and how would that happen?

Originally Posted by Kristi Silber

Jerry, what you are saying simply doesn't make sense in terms of physics. Yes, water expands when heated, but not much - certainly not enough to make a large bubble. Air expands, but a given volume of air will exert the same pressure at the same temperature no matter how many times it's heated, and if air can get in, it can get out. If each cycle of expansion and contraction makes the membrane weaker, that's different since the pressure needed to expand it would be less, but still the air will expand only so much as it heats.

Those bubbles, like me, may not have paid much attention in physics, I've paid more attention to what really happens.

Why would the bubble size have anything to do with moisture getting in, and how would that happen?

More physical space to allow for condensation of the moisture in the air - small bubbles and there is no room for condensation to develop, more room and more air allows for more condensation.

I'm not even trying to explain it, just state what I have seen over the decades and relate that information.

At one time it was physically impossible to combine, or split, atoms ... it is done every day now. Things may actually not be 'impossible' or 'against the rules of physics', just 'no current knowledge to explain what is happening'.

Heck, I can't even get my time machine to bring me back to where I started, I just keep drifting from worm hole to worm hole.

Physicists used to say that there was nothing faster than the speed of light, now they say that going faster than the speed of light may be possible.

Black holes are no longer science fiction. Yada-yada-yada.

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OK Jerry,

Your Not Helping ! Watch this woman fail to solve world's easiest math problem - msnNOW
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Aaaahhh, so now you're saying, Jerry, that what we're seeing in the photo is beyond the knowledge of man?

I'm not even trying to explain it, just state what I have seen over the decades and relate that information.

But what were you actually seeing? You were seeing a bubble grow and shrink. You weren't watching the water condense on the inner surface, or seeing more air.

What you think you're "seeing" may just be assumptions on your part to explain what's going on, no? How can you know what's happening without understanding the physics behind it?

More physical space to allow for condensation of the moisture in the air - small bubbles and there is no room for condensation to develop, more room and more air allows for more condensation.

Sorry, this doesn't make sense. If anything it would be the reverse: smaller bubbles mean higher relative humidity and greater likelihood of condensation. Water vapor condensing means a decrease in the volume of that water, so why would there need to be more space for it to happen?

As the size of the bubble increases due to expansion, it's a higher volume of air, but the amount doesn't change.

Say at the beginning you have a drop of water and a little air under the EPDM. Temperature rises, air expands, water evaporates and now the bubble is filled with water vapor. Ordinarily when the air cools back to the initial temperature, it will fill the same starting volume and the water droplet will reappear. The difference is that the rubber has deformed. It is no longer as elastic, so less pressure is needed to inflate it. Over a series of hot/cool cycles I can imagine a bubble growing through the gradual loss of elasticity of the EPDM.

Or perhaps the water droplet is a little acidic, gradually reacting with the glue and causing off-gassing. Who knows?

Jerry, how do you explain the bubbles only occurring in the taped areas?



I've found my college physics courses extremely valuable when it comes to understanding all kinds of situations in construction.