On a sheeting deck, I have xray vision.
I know where the rotten decking is before i tear off your shingles.
On a board deck(1x6)- that xray vision is slightly impaired. But after the removal of the shingles,
all leaking is apparent.
Leaking causes a yellowish, whitish stain(and trail)
on the felt and is easy to see.
Any roofer that says different isn’t a roofer.
My entire career, me or any company in my city removed the existing felt paper. Nor did any of the roofers (previous roofers on the same structure) before me.
It always made me smile to know that the roof i was working on was getting a quality felt underlayment on top of the felt from the previous roofer and the roofer before him.
Not every sheeting/decking nail on a roof wants to stay put and flush. They do sometimes back out and try to poke through your roofing material.
I want the best protection for my shingles that i can give for my customers.
Two or three layers of protection is always better than just one. It is much harder for that sheeting nail to poke through my shingles when i have more than one layer of felt.
It is also much harder for your shingle leak to go inside the house when there is multiple layers of underlayment protection.
A 4th installation of felt? no! because now i can see the laps of felt under the shingles and the roof does not look good. All needs to come off.
All that said— Today, i do tear off all felt to the decking but only because the state of florida makes me. The law has been in effect for 15 months and it is horrible. Homeowners are now paying much more for their roof and they are getting a lesser product.
Homeowners could barely afford their roofs to begin with. Now they really cant afford it and all of them are in great shock. This hurts all of us.
It does give the government another way to spend our money.
Another agency to support and spend millions of dollars of our tax money on.
All for a "decking inspection"
for your protection of course… :roll: