I just pulled up some old carpet and I'm gearing up to install LVP (luxury vinyl plank) flooring soon. I need about 15/32" of underlayment to match the existing LVP in my hallway. The current subfloor consists of ~1" planks from the 80s, and the underlayment is made of particle board, which is now half covered in dog pee, so it's definitely time for a replacement.
The only underlayment plywood I've found is only 1/4". I'm wondering if I can just lay down two layers of that and be good to go. I've also seen 7/16" OSB sheathing available, but I'm concerned that may be a rougher surface for installing LVP on top of. Any advice from flooring experts would be appreciated! I think I might be overthinking this, but I just want to avoid any issues down the line.
2 Answers
I’d say go with plywood instead of OSB. Plywood tends to be more moisture resistant, which is a big plus, especially with your previous underlayment situation. It’ll create a better environment for your LVP.
Have you considered using 1/2" plywood instead? It’s actually quite common for underlayment, and I think it might be a better option than trying to stack two layers of 1/4”. Plus, it will give you a flatter surface which is ideal for avoiding any issues with the LVP installation down the road.
I haven't seen any underlayment plywood that is 1/2”. My main concern is achieving a flat surface since the current LVP was laid down poorly and has soft spots. I want to make sure this new installation doesn’t have the same issues.

Good point, thanks for the input!