How to Repair a Roof Joist

What You'll Need
Tape measure
Circular saw
3 inch nails
Construction adhesive

The roof joist is what makes up the ceiling of a home. The joists are horizontal pieces of lumber that span the distance from one side of the home to the other. They are used to support a ceiling above, or the floor below. A broken roof joist is a serious problem that must be taken care of immediately. When the roof joist is not taken care of quickly it can lead to other structural problems like sagging ceilings or buckling walls. Here are some steps to take to easily repair a broken roof joist. 

Step 1 - Locate Broken Roof Joist

In order to get at the broken roof joist you will need to either go into the attic, or remove the ceiling tiles on a floor above. Once you locate the broken joist, mark it with a light colored marker so you can find it easily again when you get the materials you need. 

Step 2 - Measure Roof Joist

To repair a roof joist you will need to either replace the entire joist or use a spliced in piece of wood. However, replacing the entire joist gives the home much better structural integrity. To replace the joist you need to measure the entire length. Keep in mind that the joist extends through the wall. You will need to add this into your measurement. 

Step 3 - Cut New Roof Joist

Use a circular saw and cut the new roof joist to the desired length. If there are any types of notches in the old joist that are used to go around trusses or other structural elements, these will need to be also cut into the new piece. 

Step 4 - Place the New Roof Joist Into Position

After the new roof joist is cut you need to carry it into the area where it is needed. Slide it into the attic near the broken floor joist, or into the room where the ceiling joist is broken. 

Step 5 - Add Glue to Old Joist

Removing the broken roof joist before you place the new one in is not a good idea. It can severely weaken the structural integrity of your home. The best thing to do is simply glue the broken piece to the new piece. This not only keeps the structural integrity of the home, but also gives a little more strength. Spread construction adhesive along the length of the broken joist. 

Step 6 - Install New Roof Joist

Lift up the new roof joist and press it into the construction adhesive on the broken piece. This alone will not hold the joist in place so you will need to nail them together. Use 3 inch 16d nails and secure the 2 joists together. These nails should be at 6 inch spacing on both the top and bottom of the board. Nail the new joist into the structure of the home also by toenailing them into the ledger board. 

Step 7 - Replace Ceiling Tiles

If you had to remove any ceiling tiles, drywall, or other coverings for the roof, you can replace them with new pieces or those you had already used.