[costseg1]

I have one layer of 3 tab on roof - some are curling. Some contractors say OK to put architectural over. Some mention cutting or nailing curls - any ideas? Slyfox mentioned proper steps for layovers - what would those be.
Thinking of Tamko Heritage or Owens Oakridge shingles.

 

[Slyfox]

If there's a few here an there you can cut the tab portion of the shingle off.
I have also done 'three times' full tab cuts, meaning the majority of the tabs had begun curling thus we cut every single tab on the roof off before laying over with the new.

Nailing curled tabs down seems like a bad idea to me,
(don't know this for fact because I have never done it)
the curled portion will most likely crack as you nail into it and end up leaving pieces "Small" but pieces just the same of loose shingles laying between the existing and the new and when the shingles move 'natural course of expanding/contracting' those loose pieces are going to move also and very well may cause issues.

 

[Leftyho]

Hi,

I would be leary of anyone that said they were going to nail down a shingle that was curling.

Sounds like someone with little long term experience with roofing.

Shingles are dried out when they are curling.

 

[MJW]

Tear em off. You'll be glad you did.

I don't think anyone would recommend not tearing them off and starting over.

 

[Ed the Roofer]

It is hard for me to conceive that the majority of contractors you have contacted are not recommending a tear-off.

The new roof over brittle and curled shingles will not last as long as it should, nor look as smooth as it could with a tear-off.

Call some more contractors until you have one that wants to do your project the right way. Your time for a re-roof is well past it's limits.

Photos would help to be more accurate with that conclusion, so I am just going by what it sounds like from the description.

Ed