"Can solid wood treads be installed over existing concrete steps?" - It's rare that a day goes by and we're not asked this question, and the answer is more a choice of words... "can" they, or "should" they, and if I'm going to do it anyway, what's the "best" way?"

We don't recommend installing the treads over concrete and our warranty expressly excludes any failures relating from concrete moisture. The treads  are solid wood and may [read - definitely will] warp or cup because of moisture migration issues related to concrete.

Having said that, we have had people let us know they've installed them over concrete successfully. At an absolute minimum, there needs to be a high quality moisture barrier installed (either roll on or stick on) and also 3/4" plywood as decking between the concrete and the new treads. That will help with moisture transmission but it's not a sure solution.