Double paper

So we shingled two buildings, 70sq a piece. Tear off old, leave paper, (as is the norm down here), apply 30lb felt, install GAF 30yr Timberlines, cap and leave. Then the brew, hah hah starts when some twat from the building who used to be a GC pics up the shingle wrapper and claims that under a 4/12 TWO layers of 30lb should be applied. Faced with the prospect of tearing it all off and re-doing it I get all hot and bothered, read the wrapper, call Bradco, call GAF, sure enough he's right. Now, the point becomes Mute because the roof was a 4/12 dead on so we are ok, but here's the rub. I call GAF tech support,I tell the girl that we left five layers of 15lb on the roof and felted over it. She said GAF would be comfortable with that, it may be a problem codewise but not for GAF. Then I ask why do you want two layers of paper, she says added protection. I say if you have seven layes down and wind driven rain gets in then it will still find the nail hole and leak no matter how many layers she says yeah but not if the shingles are sealed properly.....well then I says if the roof is sealed then the paper becomes redundant with regard to protection. She laughs and agrees and that's that. GAF states that if you shingle a 4/12 or under, then you need two layers of 15 or 30 or synthetic but cannot come up with a valid reason......no?>>>

that`s been policy forever,They tell you to do that down to a 2 on 12 pitch in place of ice + water shield-would rather total ice shield on 2 on 12 myself,if I can`t talk them into a flat system>>>

Though I'm fully in agreement with you Jed, I have to say.

This thread has been Officially Hijacked! :side:>>>

When using BUR cant strips on the rakes, make sure your shingles are really soft before bending them up and over. Don't forget to make a piece of rake metal to cover the outside edge of the cant that comes down over the shingle mould. Otherwise, the BUR cant strip will absorb water.>>>

A few minor comments and then I'll let it go. In my opinion: Three-ply 15# definitely would be better than two-ply 15#. Two-ply 15# is better than one-ply 30#. Under tile, two-ply 30# is better than one ply 30#. We all probably agree shingling below 2/12 is insane, regardless of underlayment. Dual-80 was not better than 4-ply perforated rag. Comp shingles are two-ply. Double-coverage comp is four-ply. Laying 'shingle-fashion' eliminates berms. Laying 'shingle-fashion' allows water a chance to work back up within the system sequence. Laying shingle-fashion distracts water at dead-leak tears or penetrations. Multiple layers reduce the consequences of surface wear. Multiple layers entail heightened consciousness during installation. Anybody wanna talk about BUR cant strips?>>>

Whew!!!!Thanks for confriming Tinner.....I was worried I had lost my mind.

Expanding a bit.....I recall getting into an argument with either an inspector or a fellow contractor and going to a current code book, only to get egg on my face; There it was in black n' white...specifically referrencing the underlayment rather than the shingles....I said, "when did this happen?"..."and why/how?".....Oh me, oh my.....The sheeples/kool-ade drinkers at it again....>>>

"asphalt shingle roof assemblies between, pitches less than 4/12 to 2/12 were allowed, provided the shingles were installed "double-coverage"." Ever do something so naturally, you can't even remember to mention it?? You're right Tom. 3-1/2 to 4" exposure for shingles. I did one with Elks at 4". No ponding.No leaks. Still there. 4" to 6" laps.

My brother and I took awater hose to one. A directed spray at a 1/2" lap could let some water in. It then trickled, unobstructed, from the 1/8" gap created by the lap, straight onto the roof, on the back of the underlying shingle. The only way we could make it leak was a hard stream directed up the roof at the joints. The roof has sat under 14" of snow and ice for days.

Thanks for mentioning which double layer was called for Tom.

Ciak. How many of the blown off roofs had wood decks? I haven't seen any in the news pictures of hurricane damage. APA tests show OSB have about 1/4 the holding power of wood. I repaired one Thursday with blown off shingles. House 8 years old. Some nails were still there and I could almost pull them with my fingers. (OSB)>>>

I understand, as well as agree with you Jed.....

This is a prime example of "thinking" ourselves stupid....."Perception is reality", etc....

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Ridiculing the concept was not my intention, understanding it is. That and pointing out that GAF could not give, what I believe, a valid explanation for two ply underlayment.>>>

I'm going to start reccommending three layers of #15.....It's gotta be an improvement over two!>>>

No matter what our opinions . What is the strongest position. Judge my argument is .. I have all these professional experts with more years in the business dealing directly with this particular issue than I could possibly live or everyone , anyone on the jury ....Judge my argument ..........the manufacture who stands behind the product preforms thousands of hours static ( sitting on a board under bright lights and sprinkler systems ) testing and guarantees the performance. People of the jury you decide. Thank you for allowing me my arguments. Another reason I'm on the fence in this once great profession>>>

egg; I get your "surface tension" hint, and it makes perfect sense....However, I too have formulated my opinions over the past 30 years based on real-life experiences; Thousands of asphalt composition roofs installed under my supervision, as well as many experiences correcting inferior work of others. I'm not a proponent of the two-layer, (dry-laid, shingle fashion or not), underlayments for asphalt shingles.

I could be all wet here, (no pun intended); I recall, years ago, (couldn't tell you if it was the UBC, local bldg. dept., or a standard manufacture reccomendation), asphalt shingle roof assemblies between, pitches less than 4/12 to 2/12 were allowed, provided the shingles were installed "double-coverage". Most everyone interpeted this as double underlayment, when it actually was referreing to the shingles themselves.....This made perfect sense...Later the "code" or reccomendation wording evolved/was changed to specify the underlayment.....A valid technique was pushed aside via hearsay/public "opinion".......Can anyone validify this?...Or was I dreaming?

I remember working for a small roofing contractor, (aprx. 1980), who religiously installed two layers of felt under asphalt comp. shingles on these nearly-flat, (1/12), patio roofs attached to 4/12 main-house roof. A fairly typical design at that time. I recall getting reprimanded once for cutting all the buckles out of the felt so as to provide a smooth/flat shingle install. I wanted so much to tell the guy how stupid I felt sitting there installing shingles on this flat roof. How ludicruos the entire event was. In the following years, as a contractor, I rellished in replacing those roofs w/BUR or APP.......>>>

Hate to be a troublemaker, but this is how I see it. Two layers of 30# would be silly, mainly because it's so thick and moisture sensitive that when it buckles the shingles will heave. Two layers of 15# on pitches below 4/12 are a good idea because they work. Been there and seen it. Same for synthetic. A two-ply system offers leak-proofing benefits that a single layer will never offer. Not one on one. Two plies laid shingle fashion. As Jet would say, "believe me." We all have our rights to our opinions of course. Nobody is going to change my mind on this one. I have seen the difference too often to count. Been right down there with my own eyes and tools and scratched my own head and thought about it long and hard. Again and again. It's a great code, no matter what anybody at GAF says. I am unimpressed with GAF staff for any number of reasons. This is just another one to add to the list. Water has surface tension galore. That is the only hint I'm going to give. You guys are too smart and too experienced in too many ways to belabor the point. I believe in this case, anyone ridiculing the concept of a two-ply underlayment is just plain wrong. So there.>>>

That's STOOOPID!! What's next? Seal every nail head and the laps of the felt? At least it would serve a REAL purpose! lol By the way #15 felt should be outlawed! lol>>>

If I am using the term right...I "dutchlapped" a repair on a school before. There was a dip in a beam and the right and left beam was 8 inches higher. The dip was about 8 ft wide...created a river just about...overlapped several inches to prevent water moving horizontally under the next shinle. The center shingles, we sealed each side of the key way. THE DISTRICT WASN'T READY TO PAY TO ADUST A 40 FT BEAM.

DID I JUST "DUTCHLAPPED"? I DIDN'T FEEL LIKE A GOOD ROOFER AFTER THAT! ITS HOW THE CO. WANTED IT THOUGH!>>>

I believe you and I are on the same page. :)>>>