How to Replace Joist Hangers
Joist hangers support the weight of your floor, as well as that attach your joists with nails. Through accidents or simple wear and tear, your joists or joist hangers may become damaged. Unfortunately, the replacement involves removing floorboards to access the damage. If you are willing to do this, you can replace your own damaged joist hangers. The steps below will explain the repair process.
Step 1 - Access the Damage
In order to replace your damaged joist hangers, you will need to access them. In order to do this, you have no choice but to remove the boards that cover them.
You will need a crowbar and a hammer. Get them out and insert the crowbar between the floorboards. Use the hammer to tap the crowbar and slowly pry the boards apart. This method will probably damage them.
You can minimize the damage by only removing a few floorboards. If you know your joist hangers are damaged, you have probably already noticed visible damage on the surface of your floor or deck. You can use the visible damage to narrow your area of concentration and thereby minimize the number of boards you must remove.
Step 2 - Remove the Damaged Pieces
In order to remove the damaged joist hangers, you'll have to get rid of the joists as well. Once you expose the damaged pieces, use your saw to make two cuts in them. Cut as close to the edge as you can conveniently do. Then you should be able to slowly twist most of the joist—that is now disconnected from everything—out from its place and remove it completely. Do this for every damaged joist hanger.
You can now remove any damaged joist hangers with your hammer. Tap them out until they are loose enough to remove.
Step 3 - Replace the Removed Pieces
First place your new joist hanger at the correct location. Joist hangers are usually spaced 16 inches apart but sometimes 24. It should be easy to tell how your floor or deck is set up. Once you have figured out where on the ledger board your joist hanger goes, line the top of it up with the top of the ledger board. Hammer in the speed prongs; then use 16d nails (galvanized for outdoors, common for indoors) to attach it to the ledger board. Once you do this on both sides, you can insert your new joist and nail it into place.
Finally replace the floorboards, as long as they are undamaged. If they are damaged, you will have to get new ones.