I've raised the main area of my basement by using a cement mix and topping it with 3/4" plywood, and I'm happy with how it turned out, even though it took a lot of effort. Now, I need to raise additional rooms and am considering a quicker method. I'm thinking about leveling out low areas in those rooms and then stacking 2 or 3 sheets of plywood - starting with standard 3/4" plywood with a vapor barrier and adding one or two layers of 1/2" plywood staggered on top. The goal is to save time since cutting and laying plywood is much easier than mixing and pouring concrete. Plus, I've got some excess 1/2" plywood I'd like to use. I'm just wondering if there are any potential issues with this approach, especially since I'm planning to install an engineered hardwood floor on top that needs a flat surface.
2 Answers
Using stacked plywood like you're planning can lead to a very sturdy floor. Just make sure you're not doing this below grade unless you have a solid waterproofing system in place. Better safe than sorry!
It's pretty common to stack plywood floors, especially in rental situations. I've seen some places with up to seven layers! Just remember to account for the height added when installing your flooring on top, and everything should be good to go!

Yeah, I've had my basement pretty dry for years now, so I'm not too worried about that.