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Roofing paper exposure time


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I've been inspecting homes (construction phase inspections), in a particular subdivision, that is progressing at a snail's pace.

Some homes have been dried in and loaded with tile, but not roofed, for more than three months. I have been trying to determine what the maximum exposure time is for the roofing paper. I've got my own suspicion, and several opinions, but no concrete documentation. Here are the specs of the roofing paper:

30Lb Asphalt Saturated Organic Felt

The # is: ASTM D-226-97 Type II

Manufacturer is: GMC Roofing & Building Paper Products Inc.id="blue">

I've "Googled" my butt off, sent several emails and left messages to the company, and no results.

Got documentation?

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Hi Chris,

I'm sorry. Somehow I missed this post previously.

The answer is in the ASTM standard but to get it you have to purchase it with a credit card off their site.

I was taught by my Dad and in the Army that felt cannot be left exposed to weather and UV for more than 30 days without losing most of it's water shedding properties. However, I remember that I was looking at the WR Grace site a couple of months ago and studying some of their products and I remember that their best underlayment is rated for a maximum of 60 days while their Basik® was rated for 30 day exposure.

Instead of googling for felt, google for "roofing underlayment" and then search within the results for "UV exposure" or "Maximum exposure".

Does that help?



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Originally posted by Darren

Try this link:

http://www.na.graceconstruction.com/und ... _18506.pdf

Thanks for trying, but the product you're linking to is Grace Ice & Water Shield. I'm looking at 30LB felt.


I googled every combo I could think of and nothing addresses it. I'm amazed that a product that is so widely used (and misused) has so little public information!

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I have seen 30 days to 6 months, just depends on the product.

Here is from Grace. Installation of the roof covering can proceed immediately following underlayment application. Grace Tri-Flex 30 cannot be used as a primary roof covering. The product is not designed for permanent outdoor exposure. The installation of the final roof covering should take place within 6 months.

Mike link also has 6 months.


Take a look at the back side of the label and it most likely will tell you the exposure time for that product.

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Mike, Monte, et al,

I appreciate the help, but I still can't find a specific reference for exposure time. The link Mike offered said most felts are 60-90 days, but I really can't quote that, it's more anecdotal than specific.

Monte- I've gone as far as finding new rolls and peeling off the label, but there's no reference to exposure time. I will likely have to buy something from ASTM, but I'm not sure what.

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  • 8 months later...

Prior to semi-retiring to Arizona, I was in the Construction industry for 42 years, the last 25 as estimator/project manager for several roofing companies in the San Francisco Bay Area. The "rule of thumb" for 30 lb. exposure to the ultra violet rays of the sum was ALWAYS 30 days. Our companies were larger commercial/industrial so we did few, if any residential projects but I know general contractors always want to get the weight on the building first.

Down here in Bullhead City, Arizona we have summer heat averaging 105 to 120 degrees and one sub-division in particular has left tile loaded on felted and batted homes for over 5 months. Just because I always did everything by the book, I would like to cause trouble for this contractor but can't, like the rest of you, find anything in writing.

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  • 7 years later...

Presently, I have been dealing with this very same issue. Due to delays (i.e., weather, stucco application, etc.) in adding the top material (Spanish Tile) to our Mediterranean house build, we have noticed our 30 lb. felt exposed since Oct. '13. It is now March 2014. Much of what I am about to say has been purely from self-education and persistence in uncovering the truth.

The original plan was to apply Ice & Water Shield (Guard). This product does contain a published exposure rating of approx. 3-6 months. However, the reason why felt does not is because it isn't meant to be exposed, period. There is supposedly both installed, but why the felt was not delayed in being laid is beyond me, as this was the plan.

I was curious what was used on my roof. This roofer it had been expressed by our Architectural Consultant who works for a premiere tile company representing not only them, but others, of being reputable & in business for eons. He went on to say do not think that their bid being the lowest is short changing either you nor them. They were confirmed, as being top-notch. They only do hard roofing.

Having picked up debris, trash, etc. along the way given we have poured our heart and soul into the build on a farm I searched for something to identify what felt was used. It was Tamko 30 lb. from a torn wrapping found near the property. Holding this up to what is shown on-line confirmed the product.

The roofer had mentioned to me, that they usually like to have the felt covered within 30 days, yet what was discussed with the builder was different. Both GAF and Tamko (mostly Tamko) confirmed your question. GAF suggested it, but they did not state for certain, as they do not deal in the product as much as others.

After having called Tamko's Technical Division I asked, "Is the reason why felt doesn't list an exposure time is because it isn't meant to be exposed and covered in approx. 30 days." His reply was as follows. "Your answer is partially correct. It isn't given an exposure time because it isn't meant to be exposed, however, it's top finishing material should be placed immediately."

As far as the blogger who's client did not budget for roofing as being a priority is just poor planning. As far as, the blogger who mentioned he would not leave the felt exposed at all stands to be the only individual with correct thinking. I hope this helps, though is far beyond the time the original post was made. Sorry so tardy....better late, than never. Perhaps Custom Home Building could be referred to as a Cold War. Because even Ronald Reagan said,

"Trust, but Verify", Ronald Reagan

As and aside, for those who borrow the funding choose a reputable lender, as those involved with your project will sit more straight in their chairs when it is reminded, that the client doesn't technically own the house, the Bank (Granddad) does. Ciao!

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