With box gutters, we’re after a modern, concealed, and seamless look. The aesthetic advantage is that they blend in rather than protrude out from the roofline like other styles.
From a functionality standpoint, box gutters have a larger aperture, meaning the larger style allows them to move water efficiently. They’re actually installed and built into the roof, a tremendous benefit to flat-roof commercial structures, modern homes, and historic homes.
Moving water more efficiently extends the lifespan of the gutters themselves, but also better protects the home/structure from water damage.