How to Fix a Crack in a Roof Rafter How to Fix a Crack in a Roof Rafter

What You'll Need
Steel L channel
8 lag bolts
Reciprocating saw

A cracked roof rafter can create a sagging and unsightly roof. A cracked roof rafter needs to be repaired and can be done byf an experienced do-it-yourselfer. 

Step 1—Measure the Damaged Rafter

Before you can purchase the L channel, you need to know the size of the rafter. An L channel that is 1 ½ by 1 ½ and at least 2 feet long should be adequate for most rafters. However, you want to measure your rafters just to be sure. If you have an older home you should definitely check the dimensions. Homes more than 60 or 70 years old were sometimes built with strange components.

Step 2—Prepare the L Channel

Once you have an L channel that will fit your rafter, you will need to drill holes into it. You will drill a total of eight holes into the L channel; four on the bottom and four on the side. The holes should not be parallel with one another from the bottom to the side of the channel. They should alternate. The holes should measure 3/8 inch. 

Step 3—Prepare the Rafter

Depending on the damage to the rafter, you may have to remove large splinters or cut out damaged portions. You should only remove portions of the rafter that will inhibit you from laying it flat on itself. You can use your reciprocating saw for this work. If you don’t have one on hand, a chisel will work for this job as well.

Step 4—Secure the L Channel

You will attach the L channel to the rafter before you attempt to repair the rafter. Set the L channel on the rafter and drill four pilot holes. You should attach the L channel only in the four holes furthest away from the damage. You will drill two holes in the bottom and two holes in the side. To secure the L channel you will run 2 3/8 inch lag bolts into the bottom and the side. Tighten bolts with a wrench.

Step 5—Set Channel Flush with Rafter

Now that the L channel is secured to the rafter, you can begin the process of repairing the crack in the rafter. You’ll need to measure the distance between the rafter and the L channel. With one side of the L channel secured, there will be a space between the unsecured side of the L channel and the rafter. This is the space that has to be made up by drilling lag bolts into the rafter through the L channel. 

The lag bolts need to be about an inch and a half to 2 inches longer than the space between the L channel and the rafter. For example, if the space between the L channel and the rafter is 1 inch, the lag bolts need to be at least 2 ½ inches. 

 You will drill the lag bolts into the four remaining holes in an alternating fashion. You will screw into the two interior holes until the space between the L channel and the rafter is about ¼ inch. You will then switch to the next two holes. You will drill into those until the space is now ¼ from the rafter. You will continue in this manner until the L channel is flush with the rafter. 

You may want to add additional support to the rafters by inserting 2x4s from the floor to the ceiling.


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