Discussion Starter · #1 ·
I'm installing new hardwood in an older house with 5/16" subfloor. The house was built in 1954 and 5/16" is too thin of a subfloor to install hardwood over. So I want to put an extra layer of 1/2" OSB over the 5/16". My question is, should the additional layer of 1/2" OSB be tongue and groove? Or is that not necessary since there is already an existing subfloor already there?