After 12 months it's your decision. I've provided warranty work three years after installation. You never know when someone will hand you a $20,000 job. However, if someone were rude and demanding about it, I may tell them that they're 12 months out of warranty.
We send a letter to every customer right around their 12 month anniversary for the work we performed. We encourage them to renew their annual service agreement with us, which extends their warranty along with all the other benefits . No renewed service agreement- no replacey breaker.
Is a great idea, but your state laws first, here in Jersey, we have to give a 2 year warranty, by law, and if we offer a service agreement, the state laws are such that additional bonding may be required, and the service agreement must contain all the state rules and exceptions, some states have no limits or rules to service agreements.
I make a specific point of handing all customers a printed sheet with my contact numbers and business information. I also have on there that all materials and workmanship are warranteed for 12 months. I also ALWAYS verbally explain our warranty coverage to the customer.
Since all the GC's have the same policy I'm not inviting thier wrath by limiting my coverage to the same as thiers.
That being said, I am a softie and often "eat" out of warranty repairs or at least a substantial amount of the hours involved, especially if I feel we were at all involved with the problem because of the original install.
You have to cut free service of somewhere and since I know myself to be a bit soft on chargeing customers....well...at least this cuts down on the requests for free service...;)