Non high temp underlayment used under metal roof

Roofing/Construction Questions
#1

Hello - Thanks in advance for any feedback on this. I just found out that the underlayment used under my new metal roof is not the high temp version. My home is south facing, and I get 300 + days of intense sun a year. Looking for feedback – how big of deal is this? What will likely happen? Is the roofing company that I used going to be on the hook for redoing the entire roof, if so, can the metal be reused?

Additional info:

Roof- Decra shake XD

Underlayment- Certainteed Ice and Water (on entire roof)

#2

Your best bet is to contact a deca rep and ask them. They may not require hi temp underlayment as I believe some of them are laid on a batten system. However, I’m not very familiar with any of those style roofs. Honestly, I doubt it would ever cause an issue.

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#3

https://www.decra.com/understanding-roof-underlayments

This is the only article i can find about decra roof underlayment requirements. Granted i just gave it a real quick look over, I didn’t see anything stating their products require hi temp ice and water. Did you contractor tell you he was gonna use it?

#4

Which Certainteed Ice & water shield did they use, they have a hi temp version.

#5

The first Decra roof we did, a manufacturers rep cam out and he was fine with the regular synthetic underlay the framers had installed.

#6

OK, thanks for the input.

#7

They used the Granular model. https://www.certainteed.com/resources/2020Underlayment_Warranty_CTR20-20-3796_LR_2001_E.pdf on the first page, you can see a chart that shows that granular is not approved for metal roofing. I called Certainteed and they said if granular is used under metal the warranty is voided. Is the underlayment warranty being voided a big deal?

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#8

Yes, my contractor told me he was using ice and water shield on the entire roof. It wasn’t until I received info on the materials after the job had been completed that I noticed that the ice and water shield that was used is not approved or warrantied for under metal roofs. This style of Decra does not use the batten system. What are the practical implications of having the Certainteed warrantied being void?

#9

Call decra,the underlayment warranty means nothing.

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#10

Pg 5 of the Decra install manual:

06/20 | DECRA.com5Installation Direct to Deck - XD®Underlayment One layer of Underlayment is required before installing ALL DECRA products in both New Construction and Reroofing applications .Underlayment shall comply with ASTM D 226, Type I or Type II, ASTM D 4869, Type I or II or ASTM D 1970 . Check local code requirements as ice and water shield and additional requirements may apply.

I would not worry about it, it is not required to be high temp.

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#11

I wouldn’t worry about it. Even if it’s not hi temp you have better underlayment than regular felt (all that appears to be required from decra). Unless they specifically said they were gonna use hi temp somewhere this doesn’t justify a reroof.

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#12

It’s a big problem. In hot areas of the country the “ice and water” can literally run out from under the metal. I’ve seen it happen in Phoenix and a few other hot areas.

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#13

Sorry i guess i should have read your follow up post. Decra may have an issue with the direct to deck application over a granulated surface. If the back of the XD gets scratched from the granulated I&W that can rust the back of the panel when condensation forms. They don’t require high temp underlayment, but they may not like the granulated surface in contact with the back of the panel which is coated, just not in granules.

They could have run a layer of synthetic or Versashield over the granulated to protect the back side of the panel. I would never install metal (Standing Seam or Any stone coated steel) directly over cap sheet or any other granulated surface product without a layer of synthetic or Versasheild.

Looking through the Decra XD SHake install manual, it does show a roof over comp but it has pink ish paper… most likely Versashield. No specific note saying it is required, but i suspect Decra would want a separation layer. The Versa Shield is also required by Decra for a class A assembly so you get your separation layer and Class A.

Donl - i have yet to see it with I&W here in so cal, but we do get some tobacco juicing from modbit on occasion… maybe a call a year.

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#14

Thank you everyone for all the great input!