How long has tar paper been standard underlayment?

Old 04-07-11, 01:25 PM
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How long has tar paper been standard underlayment?

Like the topic says how long has at least tar paper been standard for underlay on an asphalt roof?

I'm having my 20 yr old roof replaced and to my surprise there is no underlay at all. On the back side where all the stacks/vents come up I had water damage and mold so I'm having to re-sheet that half. Was this just an ultra cheap/lazy roofing job?

Also I'm having rolls of bitumen membrane installed 6 ft up on the back around all the venting then tar paper for the rest.

Old 04-07-11, 02:08 PM
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We have (had?) a Pro roofer from up north....and he said it's still common not to use an underlayment (I think...maybe he said until the last few years it was common)? This was a year or so back...but most people were very surprised.

True...a properly installed shingle roof doesn't need it...but it there are errors in install or damage it gives an extra layer of protection and is required by local authorities, I believe. One of the problems it seems to have is that it dries out quite a bit over time, gets brittle, etc. It kind of loses some of its good properties. There are other (more expensive) materials that are better. I had a friend back in VA who redid the roof on his small house and used ice and water shield over the whole thing.
Old 04-07-11, 02:43 PM
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I remember in a previous thread where someone said you don't need the tar paper/felt if the roof is at least a certain pitch [maybe 4/12 or steeper] but I agree with Vic, I wouldn't think of installing shingles over bare plywood. I always though tar paper was SOP but I'm a painter not a roofer.
Old 04-07-11, 02:45 PM
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Hmm interesting I'm surprised by that too. On the portion I've seen so far that was taken off there was no water damage at all to the osb so obviously the shingles did their job. The back side where all the vents etc come up is a very different story...

Old 04-07-11, 04:47 PM
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I have never priced out tar paper, but I would think it is fairly cheap as an extra layer of protection from the unexpected.
Old 04-07-11, 06:20 PM
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Around here felt has gone up w/ the price of oil. Right now it's about $5 sq, or $20 a roll for #15 felt. Synthetic felt is more reasonable, at about $1 sq, for Grace synthetic underlayment. Yeah, it's cheap protection. I think a lot of roofing companies suggest it as underlayment, so skipping it may just void a warranty- kind of like how most siding mfg's now require housewrap behind siding.

I've also read a few posts here where this was debated (its been a while) but IMO felt should ALWAYS be used. I tore off a roof this past fall that was 35 yrs old. The shingles were about like potato chips and they came off in pieces about the same size. Tabs (masterslabs) were missing and the roof was clearly leaking. The only thing that saved it was the felt paper- and it was in almost pristine condition. You could clearly see on the felt where the dusty water leakage areas were. But the plywood underneath was fine.

Chalk up another one for ALWAYS using felt paper!!!! IMO it doesn't matter if the shingles will be laid the same day, the point is what's going to protect the roof sometime down the road if a shingle flies off that goes unnoticed, or there's a minor leak or some sort. Or how about ice dams???

Guys who don't use roofing underlayment should be shot. (not literally... just figuratively.) lol
Old 04-08-11, 12:52 PM
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If it makes any difference, here is what the 2009 IRC (Current Code required here) has to say about Underlayments:

"R905.2.7 Underlayment application. For roof slopes from
two units vertical in 12 units horizontal (17-percent slope), up
to four units vertical in 12 units horizontal (33-percent slope),
underlayment shall be two layers applied in the following
manner. Apply a 19-inch (483 mm) strip of underlayment felt
parallel to and starting at the eaves, fastened sufficiently to
hold in place. Starting at the eave, apply 36-inch-wide (914
mm) sheets of underlayment, overlapping successive sheets
19 inches (483 mm), and fastened sufficiently to hold in
place. Distortions in the underlayment shall not interfere with
the ability of the shingles to seal. For roof slopes of four units
vertical in 12 units horizontal (33-percent slope) or greater,
underlayment shall be one layer applied in the following
manner. Underlayment shall be applied shingle fashion, parallel
to and starting from the eave and lapped 2 inches (51
mm), fastened sufficiently to hold in place. Distortions in the
underlayment shall not interfere with the ability of the shingles
to seal. End laps shall be offset by 6 feet (1829 mm).
R905.2.7.1 Ice barrier. In areas where there has been a history
of ice forming along the eaves causing a backup ofwater
as designated in Table R301.2(1), an ice barrier that consists
of a least two layers of underlayment cemented together or of
a self-adhering polymer modified bitumen sheet, shall be
used in lieu of normal underlayment and extend from the
lowest edges of all roof surfaces to a point at least 24 inches
(610 mm) inside the exterior wall line of the building.

Exception: Detached accessory structures that contain
no conditioned floor area,"

Now that I have that out of my system, check the manufacturer's warranty before you accept the word of a roofer. Most mfr's have exclusions for improper installation, i.e., not per instructions. Going beyond mere installation, mfr's are now excluding failures caused by "inadequate attic ventilation."

For example here is an excerpt from the GAF "Golden Pledge" warranty:

"What Is Not Covered. GAF will NOT be liable for and this
warranty does NOT apply to:
(1) Damage to your GAF Weather StopperŪ Products
resulting from anything other than an inherent
manufacturing defect in the GAF Weather StopperŪ
products on your roof, their misapplication or the misapplication
of Covered Flashings, such as:
(a) settlement, movement or defects in the building,
walls, foundation or the roof base over which your
roof system was applied.
(b) inadequate attic ventilation."

Your state's Residential Building Code should have the information about what is required for proper installation of roof coverings/systems. The manufacturers' instructions and warranties are logically available on their web sites. Don't guess and don't take the word of someone who cannot or will not cite chapter and verse to back up their statements. That is, unless you're independently wealthy and don't care about costs, which begs the question: Why are you hanging out here?

Last edited by tldoug; 04-08-11 at 01:29 PM.
Old 04-08-11, 01:50 PM
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Big difference between building paper and felt, use the correct one (not for walls);

A little history;

Old 04-11-11, 05:49 AM
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The vents may have leaked because the rubber seal failed or someone layed the shingles over the whole roof boot. The bottom part of the boot should be exposed so it can sit on top of the course of shingles below it, not on top of it.

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