How to Straighten Sagging Roof Rafters

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What You'll Need
Hydraulic jack
1/2-inch thick angle iron
Metal drill bit
Carriage bolts

Sagging rafters can lead to serious problems with the entire roofing system. If you notice that there is a visible dip in your roof, chances are you have a problem with one, or several, rafters and you may soon be facing more issues like water leaks, bowed out walls, or your roof caving in on you. Repairing a roof rafter in this condition is not a hard project, but it can be difficult if there is not easy access. Read on to find out what you can do!

Determine the Extent of Damage

The first step is to find out how many rafters are sagging and if anything else is damaged. You may find that several are in need of straightening and that some of the sheathing must be replaced. However, it is important to fix the rafters before doing any other work to the roof.

Set up Jack

The easiest way to straighten rafters is to jack them into position. However, the trick to this process is to do it very slowly, so it may take a few weeks before you get the rafter into a position where it is straight again. Move the jack in increments of one inch to allow for the roof to be able to move with it without cracking.

Drill Holes in Angle Iron

To keep the rafter from buckling again, you will need to secure it with a piece of 1/2-inch angle iron. Each side of the iron should be four inches wide with the entire piece being at least two feet long. This will give some added strength and take care of any cracks in the wood itself.

Start by drilling at least four or five holes on either side of the iron using a metal bit.

Install Angle Iron

With the joist back in its original position, place one section of the angle iron on the uppermost section of the rafter, just before the area where it is sagging or broken. Attach it to the beam with carriage bolts, but do not tighten completely.

Reposition Jack

Once the iron is attached to the beam, you will need to work fast to make sure that it does not sag again as you reposition the jack. Remove the jack quickly and set the iron onto the entire beam. Place the jack back underneath the beam, but this time under the iron piece. Drive the remaining carriage bolts into the two by six rafter and tighten them all up. Then, lower the jack down a little at a time so that the metal can take the weight of the roof.

If there are other rafters that need to be repaired, follow the same procedure for each one of them.