I need to undercut my fireplace for an install. How deep should it be cut?

Thanks

Depending on the woods width and if it is a hearth I do different depths. Mostly I go an inch to an inch and a half if it is a solid block or stone fireplace.

The fireplace is constructed of common brick. The wood is red oak. It is coming in 3-4 and 5 inch widths.

Never heard why the width of the wood should matter on the depth of the cut ....maybe in tucson

Cut it deep enough so it's a clean look, allowing for proper expansion. I usually arrive at the depth I want, cutting in 2 or 3 passes. Cut the brick at the subfloor...then cut at the thickness of the wood. Carefully take a prybar and break the chunks out. Use a multifunction tool for inside corners. Be prepared for major dust, unless you have a vacume attachment.

Howard, I only said that because wider widths move more, solid vs engineered and he asked.

Stephen, Thank you for explaining your post. I was a little confused by the wording in conjunction with the OP

Thanks guys!