A sagging roof usually comes from one of four things: water-damaged decking or framing from a long-running leak, undersized or failing structure that was never strong enough, too much weight on the roof (layers of old roofing, or heavy tile on framing not built for it), or simply age. A visible sag is a structural issue, not just a surface one, so it should be looked at rather than ignored. It rarely fixes itself and usually points to something wet or overloaded underneath.
The most common cause we see is water. A leak that has run for a long time soaks the decking and the framing beneath it, and wet wood softens and loses its strength, so the roof begins to dip where the wood gave way. That ties a sag directly to an old, unaddressed leak. The next cause is structure that was undersized or has failed over time, where rafters or trusses were not strong enough, or have weakened, for the load they carry. Excess weight is another, from too many layers of old roofing left in place, or heavy tile set on framing that was never designed for it. And age plays in, since decades of load and weather take their toll.
Because a sag is structural, it needs a proper look, not a guess. Our roof inspection examines the decking and framing, and if water is the cause, leak detection and roof repair stop the source before more wood is lost.
| Cause | What is going on |
|---|---|
| Water-damaged decking or framing | Long leak has softened the wood |
| Undersized or failing structure | Framing not strong enough, or weakened |
| Too much weight | Extra roofing layers or heavy tile |
| Age | Decades of load and weather |
A sag tends to grow, because whatever caused it, wet wood or overload, keeps acting on the roof. If it is water, the leak is still soaking more decking every rain, as our page on delaying a repair explains. The fix depends on the cause and can range from replacing a section of decking during a repair to a full roof replacement if the damage is widespread, sometimes with a structural engineer involved for framing work. The first step is always to have someone qualified look at what is underneath, since a sag is the roof telling you the structure needs attention.
A sag is structural and worth a proper look. Call (310) 806-5959 or request an inspection below.
Tell us what you are seeing and we will inspect the structure and give you a written price for any work, with no obligation.