One possibility is the gutter is filled with trash. This could prevent rain water to move or flow from the gutter to the downspout properly and efficiently. Water will over-flow the gutter, falling from both the front and the back of the gutter. The simple solution is to monitor the gutters for trash on a regular basis.
However, our problem is not related to trash. It is related to a roofing or shingle problem. Specifically, it is related the length of the roof shingles. We have found that many fascia and soffit problems are due to shingles being improperly installed at the eave. Simply put, the shingles are "short-laid", meaning they do not extend past the fascia board far enough to allow the rain water to fall harmlessly into the gutter below. In some instances, the shingles extend only 1/2" past the fascia board.
Unfortunately, this photo demonstrates about 3/8" overhang. Since rain water subscribes to surface tension, the water does not fall directly off the edge of the shingle. It falls behind the back wall of the gutter or even into the soffit and begins the rotting process, as you can see below.
What is the solution? We can remove and replace the entire slope of the roof. That would be a profitable solution for the contractor, it is not economically feasible for the homeowner. The solution is to install a "custom" aluminum drip edge.
The two photos to the left show the drip edge prior to installation and fastening to the fascia board. Once properly installed, the rain water falling off the shingles has no choice but to drop harmlessly into the gutter below efficiently solving the problem.
The cost of installing the "custom" drip edge is miniscule by comparison to replacing a roof slope. Also, it is virtually unseen from the ground.
The keys here are to have your gutters maintained as well as inspect the performance of the gutters during a shower to determine if there is a problem. You can potentially save hundreds of dollars in fascia and soffit replacement costs by acting proactively.
