Methods to Strengthen a Floor

Sister the Floor Joists

• The joists underlying a floor give it support and keep it from caving in. A process known as "sistering" involves reinforcing the joists by fixing additional material to the side of the joist. Sistering can be achieved in several ways: securing a new joist alongside the original joist, attaching supporting lumber on one side or creating a new support on both sides of the joist for extra reinforcement. The new material can be screwed or nailed in place and usually takes the form of engineered lumber, framing lumber, steel or sheet metal.

Attach Wood Shims

• A quicker and easier but less reliable way of strengthening a floor involves attaching wood shims to the joists. Wood shims are reinforcing pieces of lumber that can serve as a temporary fix for a weak floor. The method involves inserting the shims between the joists and the floorboards

Install Trusses

• Installing trusses, which are triangularly structured units of reinforcement, can effectively prop up a floor in need of strengthening. Trusses are cut according to their fit with existing joists and nailed in accordingly. Cut only the end blocks of the truss, as altering their chords and webs could render them structurally unsound. The truss' diagonal web should point downward after installation.

Install Supporting Clips

• Clincher clips, or hurricane clips, are metal brackets that add structural support to a floor or roof. Made of galvanized steel, these clips are nailed or screwed into the intersection of the floor and the wall. More specifically, they link the top plate, wall and joist and the beam-to-post connections for extra floor support.