A new interior hollow-core door is too large to fit in the existing opening, so it must be shortened by about an inch. Earlier, the bottom was trimmed using a circular saw. What often happens is that this cuts away the solid wood at the door bottom, making the bottom of the door weak. To restore the wood, the wooden area from the sawed off portion must be reinserted into the door bottom, then glued. At this point, clamps are used to hold the recovered door wood to the outer door frame. It took a few hours for the glue to harden.