There are several types of rain gutter systems available for the homeowner. K-style gutters are very common and are used on the vast majority of homes today because contractors use a special machine to form the gutter on site to the length needed, so that there are no seams. The gutter is bent into the recognizable shape (similar to crown molding) of the K-style from aluminum coil stock. Other types include half round gutters which come only in factory made lengths, usually no more than 32 feet.
The biggest plus for the K-style gutter is the fact that there are no seams or joints which can leak. Another advantage is that the aluminum coil stock comes in a wide variety of colors to match your house. Because the gutter is one piece, however, means that it can’t be done by a do-it-yourselfer to save money. So it is usually installed by contractors, which adds to the cost.
Since the coil stock is bent on the job, the gauge of the metal can’t be too thick. That means the gutter is easily dented by falling branches and such. Copper can also be purchased in coil, but it also is a lighter gauge than sheet copper.