The main purpose of an eavestrough is to collect rainwater from the roof and drain it off away from the building’s foundations.

Modern eavestroughs are generally made of aluminum, zinc, copper, galvanized steel, or vinyl. Today, the most popular eavestroughs are seamless. They are profiled directly on a truckmount using a flat roll of metal, like aluminum for example. These eavestroughs can be as long as necessary in order to be seamless.

An eavestrough that does not work properly can cause a number of building problems. By following a few basic rules, you can make sure an eavestrough works properly and helps preserve the value of the building:

1. The eavestrough should have a slope of approximately 1 in. (2.5 cm) per 40 feet (12 m) in length. Standing water in an eavestrough may indicate that the slope is not steep enough or is inverted in certain areas.
   
   
2. The eavestrough should be 5 in. (12.7 cm) wide for residential applications and 6 in. (15.2 cm) wide for commercial applications if K-style (Ogee) eavestroughs are used.
   
   
3. If half-round eavestroughs are used, they should typically be 1 in. (2.5 cm) wider than the corresponding K-type eavestrough for the same application in order to deliver the same rainwater drainage capacity.
   
   
4. The eavestrough must be securely fastened to the fascia board under the flashing (if applicable) so the rain falls into the eavestrough and not behind it.
   
   
5. The eavestrough must have vertical downspout every 30 or 40 linear feet (9 or 12 m). A 2 in. x 3 in. (5 cm x 7.5 cm) downspout can drain rainwater from roofs under 600 sq. ft. (56 m²); a 3 in. x 4 in. (7.5 cm x 10 cm) downspout can drain rainfall from 1,000 sq. ft. (93 m²) roofs.