Your gutters and downspouts have a very important job to do, so choosing the right gutter size is important for maximizing the effectiveness of the system. In the US, there are two main gutter size standards, which are by far the most common in normal modern homes. Firstly, there are the K-style gutters, which feature troughs that are five inches wide. The second option features a rounded design with gutters that are six inches wide. Either size is suitable for homes in most of the country, and wider downspouts or more of them can usually be installed to overcome any limitations to the system.
To calculate the drainage requirements of your roof, you’ll need to determine its total square footage and its pitch. For a typical gabled roof, you only need to calculate for each slope. For more complicated roofs, you’ll need to calculate the size of each additional surface and add it all together. The next step concerns determining the pitch of your roof, also known as its steepness. Roofs with higher pitches tend to collect more rain. You can measure the pitch off your roof using suitable tools, such as a two-foot level and a measuring tape.
It’s important that your gutter system will be able to handle the maximum amount of rainfall that your area of the country can be subject to. To be on the safe side, you’ll want to know the maximum rainfall intensity, which you can find from the US Weather Bureau. This measurement is the maximum amount of rainfall in that region over one hour, and it’s measured in inches. For example, the maximum rainfall intensity in Michigan is 6.4 inches in an hour. Higher rainfall amounts and areas that are subject to large storms should have a gutter overflow system installed for maximum effectiveness.
K-style gutters, which started becoming popular in the 1950’s, tend to be the most suitable option for standard slate or shingled roofs that don’t have a lot of overhang. However, the more traditional half-round design is the only suitable option for any period buildings, but they’re also recommended for roofs with high pitches and/or overhangs. Fortunately, any specialist should be able to provide you with an appropriate recommendation based on the specifications of your roof and the local weather conditions. They will also be able to advise you as to whether or not you need a backup drainage system.