Some of the water may flow over the front of the trough and some of it may flow behind the trough.
Why water gets behind gutter.
Gutters are supposed to direct water away from your roof and into the ground.
If water is dripping behind your gutter it s probably because it was installed without any flashing over the back of the gutter.
Water gets behind the gutter.
This can be frustrating and also creates a dangerous situation on porch steps during freez.
However a gutter apron is different from a drip edge because it hangs over the gutters and then angles back toward the house.
And it doesn t stop there.
Have rain water dripping out from between your facia and gutters.
The gutter apron will prevent the dripping.
A gutter apron is similar to a drip edge in that it fits under the shingles and protects the roof deck.
When the latter happens it can seep in between the back of the gutter and the roof or soffit and fascia.
When the roof shingles do not extend past the metal drip edge the water will suck back on the metal drip edge this is called capillary action and run behind your gutters.
The gutter apron prevents water from ever reaching the soffit by leading water straight into the gutters.
So instead of moving the water away from your home the gutter is actually contributing to water damage occurring to your roof.
Being a manufacturer of roof edgings and an installer of gutters i know first hand it s not always possible to get the gutter behind the drip.
If the gutter is clogged some of that water will back up on the roof soaking it.
For example most ranch style homes have a 3 12 or 4 12 pitch roof.
A gutter apron is a bent piece of flashing that tucks up under the shingles and over the gutter.
Capillary action is a water activity in which water adheres to a surface and follow the surface.
The other element is if the gutter is not installed behind the drip edge it creates an air gap between the top of the gutter and the bottom of the drip edge which allows a place for the water to go.