When preparing to install luxury vinyl plank (LVP) flooring over existing glue-down engineered hardwood, addressing hollow spots is crucial. These hollow areas can cause unevenness and compromise the durability and appearance of your new floor. From personal experience, the best approach is to first identify all hollow spots by tapping or walking over the floor to locate any weak or hollow sounds. Once identified, these spots can be fixed using a combination of floor-leveling compounds, adhesives, or even strategically placed shims to stabilize the subfloor. One helpful method I've used involves injecting a high-quality floor patching compound underneath the hollow spots and pressing them back down to create a solid surface. Allowing the compound to cure fully before proceeding prevents any future shifting or squeaking. Additionally, ensuring that the old glue-down hardwood floor is clean and free of debris helps the LVP adhesive bond properly. Skipping this step might lead to longer-term issues such as plank lifting or cracking under foot traffic. Taking the extra time to fix these imperfections not only prolongs the life of the LVP flooring but also makes the entire installation process smoother and more satisfying. Whether you're a professional flooring installer or a DIY enthusiast, meticulous preparation will always yield better results and help you avoid costly repairs down the road.