It means that the gutter will not be overfilled during periods of heavy rains as there is enough space inside the gutter.
Overall difference in water volume between 5 and 6 gutter.
In the past residential homes have 5 gutters and 2 x3 downspouts and commercial buildings have 6 gutters with 3 x4 downspouts.
If you want the best performance from your gutters and have a larger roof area then 6 gutters along with the larger 3 x 4 leaders downspouts are able to handle approximately 50 more water than a regular 5 gutter.
Able to handle carry more water.
In this round the 6 inch gutters.
For those torrential downpours 6 k style gutter can handle a larger volume of water than 5 k style gutter.
A larger gutter actually will hold more debris than a standard five inch gutter and is not self cleaning.
To find out that is better the weight of the dimensions considered should be compared when both gutters are filled with water.
Six inch troughs can hold twice as much water as 5 inch gutters.
The difference is about 50 of the amount of water treated by the 5 inch gutter.
Also the steeper the pitch of the roof the more wind driven rain it will take.
With these systems a large load of water can overwhelm 5 inch troughs with their swifter flow rates.
Currently we are seeing more residents expand their downspouts to 3 x4 and some even install the complete 6 gutter system.
Now pay attention to the weight of the gutters.
K style can handle more water than half round and a 5 k style can handle about much water as 6 half round.
This further decreases the chance for overflow of your gutter even during the hardest of windblown downpours.
But even among k style aluminum there is a wide range of choices mostly regarding thickness which ranges from 019 to 032 but also on finishes.
Half round is also a lot more expensive than k style.