回複：非常感謝。zillow上是30年，但銀行評估房價時說是50年。

You should read this first:

http://www.schumanteam.com/Blog/Is-Zillow-Really-Accurate-Check-This-Out

After reading this, whether you should trusts Zillow is a decision for you to make. For your information, your county recording office does have a title on the house. The county tax assessor office does maintain tax records for the property.