Guaranteed for life. Great Lakes Window believes so strongly in the durability of its products that it offers a lifetime limited warranty on the entire window unit - and it's transferable. In addition, Great Lakes Window "windows" are backed by an unprecedented lifetime, non-prorated seal failure and glass breakage warranty. This warranty covers your windows for as long as you live in your home... and because it's transferable, it protects your home's resale value if you decide to move.