In almost every instance gutter installers take the path of least resistance and shove the gutter right underneath the roof shingles instead.
Overhang roof to gutter.
How far into the gutter should roof tiles project.
Here phil explains how much overhang a roof should have at the gutter.
Metal is usually installed on rafters or strip sheathing rather than the solid decking used under other materials.
Some slight overhang is recommended in conjunction with a drip edge flashing to prevent water from getting under the roofing and onto underlying wood.
Once free slide the drip edge out and discard.
Gently lift up the shingles on the edge of the roof and locate the nails holding the existing drip edge onto.
Greater overhang becomes a point of leverage for gusts of wind to rip off your roofing.
A typical metal roof overhang may be 2 to 4 inches or even less.
In this video we demonstrate how to install a gutter for a shed metal roof or house.
Many installers deliberately bend down the overhang into the gutter to assure no wind blown rain goes between the overhang and the gutter effectively preventing water incursion behind the gutter.
It can be done.
The bottom tile or slate of the roof covering should project at least half way into the gutter the ideal distance is between half way and two thirds of the way over.