My roof was damaged during a storm. What can I do to reduce the chance of this happening again?
This is a good question. Anytime we are repairing our homes we can make them more hazard-resistant. Damage to roofs is the most common damage resulting from wind storms, and we can take actions to minimize future damage.
The damage you have can vary widely. It could be the replacement of just a few shingles or the whole roof -- rafters, sheathing and all -- was damaged. We will take the worse-case situation and start with the rafters. Let’s assume we have to replace several pieces of sheathing, several rafters were broken and all the shingles need to be replaced.
Rafter repair has to be the first step. Remove the sheathing that was damaged and evaluate the rafter damage. In some cases the rafter may be only cracked or split, and a scab rafter can be attached to the side of the old rafter. Use lumber the same size as the old rafter and nail or screw the new member to the old. If you can get to the location where the rafters attache to the wall top plates, attach tie hurricane straps. This is a very vulnerable location. Take time to add as much strength as possible. Several types of straps are available.
If possible, go ahead and install these brackets connecting all the old rafters you can reach. Even if you can only connect a few, you have helped the overall strength of the roof resist uplift forces that might be caused by high winds.
Once the rafters have been repaired or replaced, the damaged sheathing will need to be replaced. Here again, even if you are replacing only a few sheets, do it right. If the entire roof is going to have the shingles replaced, remove the old shingles and the underlayment so you can see the bare sheathing. New codes and prescriptive designs describe nailing patterns and spacing for attaching the sheathing to the rafters. It is suggested that you follow these recommendations adding enough nails to comply.
Now let’s look at new ways to weatherproof the structure. With the materials that have been used in the past, when the shingles blew off or the tabs were damaged, wind-borne water would often find its way through the old underlayment (felt paper) and into the structure. Often this water would cause major damage. New products and methods of installation should reduce or eliminate water from entering the home. Recommendations call for the joints of the sheathing to be taped with self-adhering bitumen tape designed for that purpose and then a layer of self-adhering modified bitumen underlayment (complying with ASTM D 1970) placed over the sheathing. Taking these steps minimizes the chance of leakage.