How Thick Should Wood Floor Underlayment Be?

An underlayment is the “meat” in the wood flooring sandwich. Top is the finish flooring; that is, the wood flooring that you see and walk on. Very bottom is the subfloor (okay, well the floor joists are at the very very bottom…). Between the subfloor and finish floor is the underlayment.

How thick should the underlayment be?  What kind of materials should be used for underlayment?

Underlayment Thickness and Material

It all depends on the condition of your subfloor.  If you’ve got a nice, perfectly smooth subfloor, you may not need any underlayment.

But if you have a problematic subfloor, your underlayment will be anywhere from 1/4″ to 1/2″.  You can even install up to 3/4″ thick underlayment…or thicker…depending on your needs.  Really, the sky is the limit.

Problem with installing thicker and thicker underlayment is that you shoot yourself in the foot–you’ll have problems with making transitions from one floor to another.

Plan on installing the flooring everywhere (i.e., no transition problems)?  Then you’re still dealing with transitions to the outside.

The most common material for underlayment is good old plywood.  Or you can install what is called Oriented-Strand Board, or OSB.

Oriented Strand Board - OSB
Oriented Strand Board - OSB

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