Only use 100% urethane-based adhesives when installing stair treads made of solid wood! Water-based adhesives will cause the wood to warp if too much is used. We strongly advise you to read the recommended adhesives followed by nailing to ensure thorough grip and durability. An adhesive with a high moisture content will ruin a set of RetroFit stair treads and is not covered by our war... https://www.stair-treads.com/instructions-how-to/installation-video.html