Dirt Touching Siding = Rot.
Dirt is not only dirty, it also contains billions of little microbes that need to eat something organic to survive. Dirt also holds in water like a sponge. Obviously there’s a lot of nutrients in dirt but there are even better nutrients in the wood that your home is probably built of. With a little bit of dampness laid up against almost any wood that has not been fully pressure treated propagate rot first will invade your house and have a good meal. Dirt builds up around the foundations of homes because people mulch over mulch over mulch and over time, on sloped sites the dirt around your house literally slumps to a lower level and ends up building up above the line where your siding stops. Even if your home is made of stucco or brick, it is really a good idea to find where the foundation ends and that hard surface begins because in the stucco, brick, or stone in most homes is a veneer set over wood and if dirt builds up against that material, water will find its way in and begin the process of eating your house. Fortunately, the solution is simple and can be done by anyone with the strength of a 14 year old to simply shovel or rake away the material that’s building up until it’s at least 6 inches (most experts say a foot) lower than wherever the wood part of your house begins – siding or structure.