Installing carpet and padding? A new wood floor? And, as result, you've got to trim off an interior door? Here's how to refill hollow doors after they're cut way up for clearing new floors. Solid doors are easy to cut off to any height, but the bottom wood edge of a hollow door only extends up a few inches. If it must be trimmed off higher than this edge, the hollow inside is left open and exposed. Here's the solution to that problem: From deep with the Carey Brothers' vault of "Don't be annoyed, just fill the void," we bring these words of wisdom. Indeed, says here to refill the open hollow core, rip a 2 X 4 to the proper width, then cut to length so it fits snugly and replaces the missing bottom edge. If any inner-core material is in the way, apply some wood glue inside the door and tap the refill into place. It will be as good as new. And that's the On The House tip for today.