A little over 5 years ago I had my roof replaced . The roofer salesman upsold me an ice and wind shield on the entire roof deck . When they were installing it I think the office never told the installers that roof was suppose to get the IWS so the entire roof was word with regular synthetic underlayment . Then they found out I was supposed to get the ice and windshield, and they placed it over the synthetic underlayment without removing it . I have original pictures from the installation, showing a large amount of wrinkling in the ice and windshield during the installation process.

Now it’s five years later, I’m selling the home. I had a home inspection point out that my shingles were buckling in some areas. The buyers roofer came over and said the underlayment wasn’t installed properly, and that I need an entire new roof . of course, the roofer that did the work a warranty claim with GAF, but I don’t think it’s a claim with a product failure. I think it’s a claim with a product being installed in properly from the beginning

my question is, can you even install ice and windshield over synthetic underlayment because if you cannot, it is definitely a case of being installed incorrectly