A sagging roof is one of the most alarming things a homeowner can notice. Unlike a missing shingle or a small leak, a visible sag signals potential structural failure — and in Savannah's humid climate, the causes are often moisture-related and progressive.
What Causes a Roof to Sag
1. Water Damage and Wood Rot (Most Common in Savannah)
Prolonged moisture exposure causes plywood decking and rafters to rot and weaken. In our high-humidity environment, even small leaks can saturate wood over time. Once structural wood loses integrity, it can no longer support the roof's weight, causing visible sagging.
2. Inadequate Structural Design
Some older Savannah homes were built with undersized rafters or insufficient bracing. Over decades, the cumulative weight of roofing materials (especially if multiple layers were added) causes gradual deflection.
3. Too Many Roofing Layers
Georgia code allows a maximum of 2 layers of shingles. Some older homes have had 3 or even 4 layers added over the years without a tear-off. Each layer adds 200-300 lbs per square (100 sq ft) — that is a lot of extra weight on aging framing.
4. Termite or Pest Damage
Subterranean termites are extremely common in Savannah. They can hollow out rafters and structural members from the inside, leaving the exterior looking normal while the interior is compromised.
5. Storm Damage
A fallen tree limb or extreme wind event can crack or displace rafters, causing localized sagging that may not be immediately obvious from the ground.
Severity Assessment
| Sign | Severity | Action |
|---|---|---|
| Slight dip visible on close inspection | Moderate | Schedule inspection within 1-2 weeks |
| Visible sag from the street | Serious | Call a roofer this week |
| Sag with cracking drywall inside | Critical | Do not occupy — call immediately |
| Sag with bouncy/soft feeling underfoot | Emergency | Evacuate and call a structural engineer |
Repair vs. Replacement
A small localized sag due to a few rotted decking sheets can often be repaired during a roof replacement for $500-$2,000. A structural sag involving compromised rafters or trusses is a major repair requiring a structural engineer and potentially $5,000-$20,000+ in structural work before the new roof can go on.
Notice a sag in your roof? Do not ignore it. Contact us for a free assessment — we will evaluate whether it is a cosmetic issue, a decking problem, or a structural concern that needs engineering attention.
