I need to remove a piece of tongue and groove OSB subflooring panel to get some wiring through to my attic. What’s the best way of doing this?
If the T&G OSB subflooring panel has been screwed in place, you will easily be able to remove a piece of the OSB subflooring panel. If the subflooring has been glued and nailed into place, it will be more difficult to remove a piece. In this instance, you may want to consider making holes through the ceiling below and though the subflooring to feed the cables through.
If removing a piece of the OSB subflooring is the only option, use a circular saw to make a cut down the long edge of the T&G between the sheets of subflooring. Make the cut 1/8 inch less than the thickness of the OSB subflooring to prevent cutting the attic floor joist or truss bottom cord as this will damage the wood framing.
Cut the T&G on the two long edges and carefully remove the fasteners and gently pry the OSB subfloor panel from the floor joists using a pry bar. Do this carefully so that if you have missed a nail, it won’t damage the panel.
If glue has been utilized, you may need to cut out each rectangle of the OSB panel between the floor joists rather than removing the whole piece.
Complete your wiring, then cut and nail pieces of wood blocking under the longest edge of the subflooring to replace the tongue you cut when removing the panel.
You can also take this opportunity to beef up your insulation in the flooring while you have the panel removed.