Roof underlayment required?

Inspected a home today – 12 years old. About 3’ sq. patch of asphalt shingles was missing. No underlayment was visible. Picked up the shingles at the edge and no underlayment was visible.

A veteran general contractor on the jobsite said it was not required then or now, saying “think about it, the underlayment is full of holes too”. Guess he’s got a point there. He said even today, when a roofer gives him a price on a roof installation, the price differs depending on whether underlayment is included.

I believe underlayment is required in IRC R905.3.3. How long has it been required? Thanks.

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I thought it has always been required by the shingle manuf’s.
Many roofers etc. wrongly believe it is only to keep the house dry before the shingles are installed.

The main reason for underlayment is to allow sheathing movement without cracking the shingles. The shingles will adhere to the sheathing. It is not just expansion and contraction either, roof structures move during windy conditions. I also believe it is good to prevent or greatly reduce any leaks that will likely occur during the lifespan of the roof.

I would say it has been required since common sense has been in existence also.

Good points Bruce.

The contractor told me the history of underlayment is this: “to get a draw on a construction loan, you have to have the building in the dry…the underlayment qualifies as having it in the dry and that’s why it it done.”

I like your logic better.

I’ve seen 2 in the past two weeks (both less than 15 years old) without underlayment. Be on the lookout!

I had a 4 unit two story building once that had an acceptable roof looking from the front. The rear was not visible due to height, low slope and lack of room in the rear. I put the ladder up and could not believe it, shingles barely overlapping with hundreds of nail heads showing. They had to make the bundles stretch until the job was done…

Most roofing shingle manufacturer’s will void the warranty on the roof if the underlayment is ommitted.

Underlayment is required, according to most shingle applications.

Here’s Owens Corning installation requiremernts…

]( See 1a and 1b (top right)

A roof without underlayment is a roof that will leak much more quickly than a roof with underlayment.
Shoddy workmanship, usually dictated by trying to save money buy cutting corners.
And in this case, no one will ever know that the underlayment is missing because who is going to remove shingles to see if it’s there?
Mother and Father Nature, that’s who.
Builder lawsuit waiting to happen.

From the pic it appears as though there is felt paper.


I require it to meet my common sense theory…when I roofed (rooved?) houses back in the 80’s with dear old dad…that was my favorite part of the job…slamming the staples into the underlayment…but dragging those rolls of paper up the ladder sucked…I was a Jr in HS and weighed 117 pounds and was 5’1"…the felt paper weighed more than I did almost!

Those must have been some supersized rolls of felt!:wink:

Undersized kid.

I know how that works to!
I started doing stucco when I was 17 and about 120#
The first year I gained 60#! I thiught my father inlaw was trying to kill me for what I did to his daughter!:mrgreen:

Bare wood.

I see bare wood. Looks like plywood. Good grade plywood, too.
I think that might even been a knothole there in the lower right of the wood.

If there is felt there, then someone got up there with their Exacto knive and cut it all out where the shingles are missing. Did a real nice, purty job, too.

Of course, Joe was there, and he says there wasn’t any.
I trust Joe.
Well, pretty much, anyway. :smiley:

Well I’ll just have to take your word on it. I thought I saw a cap nail near the top left corner of the opening. The shading in the pic looked like waves in a paper, it could be wood grain as well. Knot holes? I don’t know, my picture must knot be as crisp as yours. They skimped on the nails too, looks like two per shingle. That will help the shingles fly away every time.

Ralph, i think what your seeing is actualy the first layer of ply that has gotten wet and swelled, dried and wrinkled, as all plywood does when it’s been wet. i thought it was paper too at first.:wink:

Bruce ,

You are absolutely correct. The tar paper acts as a slip sheet which allows the movement between the roof shingle and the sheathing, otherwise cracking and stress will occur.

Louis Agudo

I guess Ralph and I have the same eyes, from that pic it sure does look like tar paper to me