The simple answer is the power of water to damage your home. If there are no gutters to prevent it, the roof of a house collects the rainfall and creates a river of water that flows down the slopes and tumbles over the roof edges as a waterfall. On an average house one inch of rain causes 500 gallons of roof water. This concentrated water flow will seep into every nook, crack or small hole in the exterior house walls and around the window casings as the water flows down the exterior walls.
This dampness behind the exterior wall can rot out the inner elements of the house and create mold and mildew. As an example, my brother-in-law of all people owned a house with a gutter on the front but not on the rear. When the contractor he hired to do some interior remodeling hit an inner wall with a hammer it went right through the inner wall and outer exterior wall into the backyard. So instead of just the interior, he also had to rebuild a very large section of exterior wall. An expense he did not expect.
Gutters protect your house's foundation. The expansion and contraction of the soil around your house is the number one reason for foundation failure. The drip line that is created on the ground becomes a pooling area. After periods of rainy weather the soil around your foundation becomes saturated and expands. Hot, dry weather then causes the soil around the foundation to contract and pull away. This repeated cycle can compromise the support around your foundation and result in cracked masonry and/or undermine the foundation. In addition many houses (including mine) can keep water out of the basement by simply having extensions on their downspouts to direct the large volume of roof water an extra 6-10 feet away from the foundation.
Rainwater cascading off an un-guttered roof will hit the ground with enough force to cause splash-back of dirt, grass and minerals on the exterior walls. Over a short period of time stains appear that are difficult to remove or hide. Plants, flowers and mulch under the drip line of an un-guttered roof will be damaged and this over watering condition can permit harmful fungus to develop as well as attracting ants, roaches and termites.
Protect yourself from unforeseen expensive repairs, protect your investment in your home and keep your home looking good with the reasonable cost of new gutters.
Contractors: please feel free to duplicate this for use with your customers.
Eagle Seamless Gutter, Inc.
Wakefield, MA 01880 (781) 334-4444 EagleSeamless@aol.com