If we have to summarize it in a single rule, gutters need a downspout about every 30 to 40 feet. For most homes, this means installing pipes at each end of a gutter section. In general, you should have one downspout for every 40 linear feet of gutter. This location allows for adequate drainage and will prevent the gutter system from overflowing during heavy rains.
When rainwater overflows the gutter system, it completely avoids downspouts and falls to the ground right next to the foundation. This can cause leaks and even cracks in the base, which are much more expensive to repair than installing the right number of downspouts. The downspouts in a gutter system play an important role because they ensure that water drains efficiently. The general rule about placing downspouts is that one is needed for every 25 to 35 linear feet of gutter.
The maximum length of the gutter between the downspouts is 40 feet. If you are in a high capacity situation due to roof slope or rainfall levels, adding additional downspouts can increase the drainage capacity of the gutter. Reduce the required size of your gutters by installing more downspouts than the standard spacing of one every 40 feet. The number of additional downspouts needed to increase the capacity of the gutters will depend on the size of the downspout.
If you live in an area with a high maximum rainfall intensity, you'll need larger gutters to prevent your system from being overwhelmed by sudden, heavy rains. However, if you want to install a completely new gutter system, you'll need to take some roof measurements to find out which gutter size is best. You can also use traditional-sized gutters if you have a professional increase the inclination of the gutters during installation to increase capacity. The Thompson Creek replacement gutter system even reduces the need for regular maintenance because it includes gutter hoods that filter out a large amount of common waste.
If the roof of your house has a steeper slope, there is a high risk of wind-blown rain accumulating in gutters. Clogged gutters are worse than not having gutters because they channel water directly into the ceiling, where it can cause serious rot. While semicircular gutters offer aesthetic benefits, they generally don't move water as efficiently as type K gutters. I would remove the fascia that was added and then add semicircular gutters that still show the tails of the beam a little unlike K-style gutters.
To determine the size of gutters you need, you will first need to calculate the square feet of the drainage area of the gutter. If you already have gutters installed and need to replace all or part of the system, you can measure existing gutters to determine their width. Downspouts are the part of a gutter system that forms the connection between the roof and the ground, allowing rain or melted snow to pass from the roof to the ground. If you're choosing K-type gutters for a roof area of less than 5,500 square feet, a standard 5-inch gutter size is the recommendation.
In general, larger gutters require a custom order with a professional gutter installation due to the additional weight. The answer to this question varies slightly depending on the type of gutter system you install and, of course, the size of the roof you are going to install.