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Roof drip edge flashing installation details (C) Daniel Friedman Roof Drip Edge Flashing Requirements

  • DRIP EDGE FLASHING for ROOFS - CONTENTS: what are the requirements for roof drip edge flashing? Where should it be installed, in what position, and what is the relationship between the placement of drip edge flashing and roofing underlayment or ice and water shields & shingles or other roof coverings?
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Roof drip edge flashing installation requirements:

Is drip edge flashing needed? How & where should it be installed on roof eaves & gable ends? This article discusses the requirements for roof drip edge flashing. We explain where drip edge flashing should be installed, in what position, and we describe the placement of drip edge flashing beneath roofing underlayment or ice and water shields & shingles or other roof coverings.

This article series discusses roofing installation, including roof sheathing, roof underlayment, roof coverings such as shingles, slates or membranes, and roof flashing.



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Roof Drip Edge Flashing at Roof Eaves & Gable Ends

Close-up of the profile of roof drip edge flashing (C) InspectApedia.com

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Roof drip edge flashing serves multiple functions on a building, the foremost of which is to assist water in leaving the roof edge with minimum damage to other building components by directing the water off of the roof and into the gutter. Without this detail water leaving the roof edge wants to run down building fascias, soffits, and walls, sometimes even entering and damaging the structure. The drip edge also gives us a nice straight edge with which to align roof shingles, slates or other roofing material. Drip edge varies in dimensions but typically the flange that nails to the roof surface is about 2.5" wide and the vertical edge that directs roof runoff down and away is about 1.5" in depth. Lengths of drip vary but typically it's sold in ten foot lengths (120").

The sketch above illustrates the end-profile of roof drip edge flashing and shows its placement on the roof. Usually you won't see much of drip edge as it's under the roof shingles, under the underlayment, and behind the roof gutter. But where no gutters are installed you might get a peek.

Drip edge on a metal roof showing water being directed off-roof (C) Daniel Friedman

Our photo above shows what we ask of roof edges: if there is no gutter, water leaves the edge and zooms out into space away from the building. If there is a gutter, water leaving the lower roof edge is directed into the gutter, not behind it, not down building walls, not where we don't want it to go. The brown drip edge is properly installed and is doing its job. Most of the roof runoff is going off the roof not down the fascia board.

Where Should Roof Drip Edge Flashing Be Placed ?

Roof drip edge flashing installation details (C) Daniel Friedman

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Our illustration above shows proper placement of the roof drip edge atop the roof sheathing - before installation of roofing felt or ice and water shield and spaced a bit away from the fascia board to improve its drainage. Thanks to my carpentry teacher Bernie Campbalik for this tip.

What Happens if Roof Drip Edge is Improperly Placed or if Omitted Entirely?

The photo below at left illustrates use of a site-built "drip edge" nailed tight against the fascia board, leaving a gap that in turn sends roof runoff behind the gutter. At below right you see the stains on the aluminum-wrapped fascia board confirming that a lot of water is being sent behind rather than into the gutter on this roof.

Gutter and Downspout Details (C) Daniel Friedman Gutter and Downspout Details (C) Daniel Friedman

As we discuss at BACKFLOWING GUTTERS, in the photo below I'm pointing to the trouble (on another home). The roofer installed the drip edge tight against the fascia. There was no way that the gutter installe was going to get the upper edge of the gutter behind the drip edge. Some rain runoff, by capillary action runs up under the shingle drip edge and down the fascia behind the gutter. ,

Drip edge improperly installed or gutter poorly installed - water runs behind gutter (C) Daniel Friedman

Installing Drip Edge on a New Roof or Re-Roofing Job

Details of roof drip edge flashing, felt underlayment, starter shingle course on an asphalt shingle roof (C) Daniel Friedman

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Our photo above illustrates several details of roof drip edge, eaves flashing, and gable end flashing at an asphalt-shingle re-roof job we documented in Dutchess County, New York. From left to right:

Shown below: roofing white drip edge on a re-roof job.

White roof drip edge along the eaves and gable end during a re-roof job. (C) Daniel Friedman

Roof Drip Edge Flashing Mistakes & Leaks

Below we illustrate an effort to add a second drip edge (white) below the original roof drip edge (brown) to correct a problem with water running behind the gutter rather than into-it. If the gutter is not secured snugly against the fascia or if the gutter was installed atop rather than under the drip edge you'll get this problem.

Gutter Clogs (C) Daniel Friedman

On roofs with no eaves overhang or soffit, proper installation of drip edge proud of the fascia board at the wall top is very important to avoid water damage to the building walls below. Look at the worn and lost wood siding shingles pointed-to by our client who is indicating damage and missing shingles on the wall below the roof edge. The presence of more wear on siding shingles at the top of the wall than lower-down confirms a history of roof runoff streaming down the building walls.

Photo of a home with no roof eaves

As we discuss
at ROOF VENT if NO SOFFIT, the roof shown above is difficult but not impossible to vent - a step in avoiding ice dam leaks and attic moisture trouble.

The photos below illustrate how easily water will run off the roof and behind a gutter when no drip edge is present.

Loose gutter (C) Daniel Friedman Loose gutter clue (C) Daniel Friedman

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