Kinda like saying I own a car. What's it worth? lots of factors: age, condition, quality, location, accessibility, replacement cost, and many other factors all create various levels of demand(value) for an old tin ceiling. And what do you want to do with it? Remove and sell it? check with local renovators or arch. salvagers. check eBay or Old House Journal for a sense of the market. Or just want to know what value it adds to the home as it is? In place, its value is only to you, unless you are selling the house. Then it depends on the buyer. maybe ask a real estate agent. possible value can range from being a net liability to thousands of dollars, and there's no way to say from here.