A sagging roof isn’t just an aesthetic concern. Whether it’s your home or your garage, a sagging roof could indicate a serious problem. Bowing rafters, serious ventilation issues, or hidden leaks are potential causes. While not all sagging roofs signal an impending collapse, some do. It’s important to get a roofer in to look at such a roof right away. But, while you wait, you might want to learn about the potential causes of a sagging roof and how to fix them.

Is the Problem the Rafters or the Roof?

The first thing your roofer will need to do is determine what kind of sagging your roof is experiencing. Either the rafters are sagging in, or the decking is sagging. The decking is made of thin wooden panels. They span the distance between the rafters and support the shingles. If they are exposed to water, they can begin to cave in, which will look like sagging from the outside.

Fixing the Rafters

If the rafters are sagging, the only fix is to replace them. Unfortunately, this is a very involved repair that may even require the help of a structural engineer or architect if your roofer suspects the home has suffered structural damage. Rafters connect to the other structural elements of the home, and if they are damaged, the rest could be too.

Typically, rafters need to be exposed to an unusually heavyweight to start to sag. If you placed heavy objects on the roof (such as sandbags to secure blow-up ornaments), you might have caused the damage. Or, if your home had a significant build-up of snow or ice over the winter, that could have exceeded its load limits.

Either way, the rafters will need to be replaced, along with the entire roof above the damaged rafters.

Fixing Swollen Decking

If the problem is just swollen decking, the fix is much simpler. The decking, and the roof materials above it, will need to be replaced. The chances are that a hidden leak in this area caused the sagging. However, if your roof cannot find evidence of a leak, the problem could be condensation instead. Typically, this is caused by poor ventilation or insulation, which needs to be fixed or the new decking will be damaged too.

Fixing Ventilation or Insulation Problems

Condensation is happening in your home all the time, where hot air meets warm air. Typically, condensation generated in your home is vented through the attic’s ventilation and other vents in your home. However, if your roof doesn’t have adequate venting, the condensation can’t escape and could begin to soak into your decking.

Another possibility is that your roofing is generating the condensation. When a roof is not properly insulated, hot air from home moves through it, meeting colder conditions outside. Or, in summer, the reverse happens. Either way, the two different temperatures create condensation, right inside the layers of your roof. It has nowhere to go but into the decking, eventually causing it to sag.

The solution is simply to install proper ventilation or insulation in your roof.

Fixing a Sagging Roof Requires Professional Help

Fixing a sagging roof is more dangerous than typical roofing work, as there is always the chance that part of the roof will cave in. Don’t try these repairs yourself!