Learning how to replace a steel floor joist may look daunting at first, but all it takes is a bit of patience and a lot of elbow grease.
Inspect the problem
The first order of business is to determine what the source of the problem is. The old joist can be cracked, twisted, or have some problem at the rim-joist connection. If your floor is sagging, it might be that you just need to replace the joists. If the old joists are made of wood, you might want to replace them with steel joists. If the joists are already made of steel, bracing will strengthen them for the demands of your floor. Before starting actual work, do consult with a structural engineer to see if the finished construction will be within the building code standards of your area.
Step 2-Get the correct joists
Ensuring you have the correct load-bearing joists will save you time, money and future headaches. A joist is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a section of your house’s floor. It may be made of wood, steel, or concrete. Be sure to consult with a trusted steel joist manufacturer when purchasing your joists. They supply you with load tables so you can calculate for, and determine, the correct size of the joists you will need.
Step 3-Reinforcing and Replacing a Joist
Before you can take out the old joist, you have to install a new one beside the old one in order to bear the weight of the floor above it. Use the same length of joist and place it beside the old one. You may want to use rafter ties to tie them together first before taking out the old joist. Attach the new joist to the frames of the floor or structure firmly on both ends using bolts in an X-pattern.
Step 4-Bracing the Floor
Allow the new joist a bit of time to adjust to the weight before you slowly remove the old joist. This can be done by bracing the floor with a hydraulic jack. Connect the 4x6 inch beam across the underside of the old and new steel floor joists in order for it to run perpendicular to the joists. Utilize screws and rafter ties to hold the beam in place. Use 1-inch thick steel panels in between the jack and the beams to ensure equal weight distribution. Once the jack is secure, you may untie the old joist from the new one and dismantle from end to end slowly.
You may want to use a spirit level to ensure your progress is not wasted by having new joists but uneven floorboards.