A common leaky area


Water come from both side seams and then sits in the water trough. The higher side of the sure-nail
Strip where the nails get halfway shot through
Breaking through their fiberous strip


If you install the roofing and or valley metal correctly the underlayment won’t matter, I have torn off many a old roofs with no underlayment at all under the shingle that never leaked, or even seeped through


I believe your roofing experience has been very limited then.


In theory you are correct but when you throw extreme thermal cycling, snow, & ice into the mix the eaves and the bottoms of valleys certainly need some type of underlayment.

It’s easy to shingle a roof to be watertight to rain, it’s easy to shingle a roof in the snow belt also but it is a bit different than places that see no snow & ice.


Underlayment IS part of the roof.
Read any shingle wrapper, it will show you.

The matter should be which of the underlayments actually works AFTER the roof is complete.

Not which underlayment or no underlayment to make the workers job easier…

Care about the homeowner more than you care about the labor and it will pay in more ways than you can count.


I have seen a ton of horrible workmanship,
Which is almost half of the roofs i replace.
Where the laborer didnt understand exactly where to put the seams or the nails on the shingles,
but the roof lasted a respectable time because of
1-2 layers of asphalt saturated felt.

This new generation of homeowners will not get this level of protection.

You’ll see.


You do know asphalt shingles over underlayment is a relitivly new concept. Most areas did it without felt unti the early to mid 80’s. I agree it’s needed, but it is indeed intended as a “back up”, for when a shingle blows of etc.


Underlayment is required for fire rating.