I had a roof where we replaced 6 shingles and because they had not laid down and adhered to the layers below the inspector determined the roof needed to be replaced.  

Get them to remove the old shingles-all of them. 

.* We have wholesale accounts with several large cabinet companies, and granite companies and can get huge discount on these supplies, along with flooring, roofing shingles, and carpeting and other supplies.* My personal credit score is 700 and I have personal rehab capitol, but not enough to cover the home purchase and rehab costs. 

Curling of the edges of the shingles is a clear sign the roof has seen better days and needs to be replaced.  

The ridge shingles are starting to lift; seems premature for a 1 yr old roof.

Standard home being: 8’ ceilings, avg $4/sf tile and flooring materials, RTA China imported cabinets, asphalt shingles, vinyl windows, basic hardscape and landscape, no pool.

I don’t know if the amount of people or slamming down the shingles caused it break a support and then it just slowly started getting worse.

Of course, upgrading to higher end materials/shingles will throw that component out of balance. 

Most comp shingle manufacturers provide warranties on their products.

I actually ran across a few insurance companies that wouldn't ensure my first house simply because it had asbestos shingles on the outside which were original.