If you have a single cracked or undersized joist that is otherwise in good shape, you may be able to complete a small structural repair with the sistering method. The main steps include: Slowly jacking up your floor frame from below, about one-eighth of an inch per month, and placing a beam across the damaged joist and any neighboring joists. Using construction adhesive to adhere a new, full-length joist flush alongside the damaged one with your jack still in place. Clamping and nailing both joists together with columns of three nails every 16 inches at the joist's top, middle, and bottom. Cutting the sister joist to match any cuts in the original joist; these typically accommodate wiring or plumbing. Then disconnecting pipe or wiring before feeding it through the cuts made.