In addition to the drip flashing you should check that the gutters are properly affixed.
Rain running behind gutters.
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.
The gutter apron will prevent the dripping.
Is the water running down the roof not going into the gutter and instead flowing behind the gutter.
The reason water flows behind gutters is a combination of a few things.
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.
If the gutters look clear run a hose and fill the gutters with water.
If this is the case this tutorial will help you clean your gutters.
Water should run out the downspout and away from the house without filling the gutter.
Capillary action is a water activity in which water adheres to a surface and follow the surface around.
If so then there is a problem with the gutter and or flashing installation.
When it rolls over the edge it follows the contour of the edging and makes its way behind the gutter.
One main cause is simply not having enough overhang on the roof edging or the roof covering itself.
If the gutter isn t clogged then you need a gutter apron.
The first cause is when the roofing material is installed many roofers will not extend the roofing material past the roof edging or drip edge.
Some of the water may leak behind the gutters down towards the soffit and the fascia.
And it doesn t stop there.
When gutters become clogged with debris such as leaves twigs and pine needles then water is no longer effectively channeled into the downspouts and away from your home.
This does not allow the water to be carried far enough out.
If the water fills the inside of the gutter this means the gutters are clogged.
A gutter apron is a bent piece of flashing that tucks up under the shingles and over the gutter.
There are a few elements that come into play that cause water to run behind the gutter.
If the gutter is clogged some of that water will back up on the roof soaking it.