Flashing From a Shingle Roof Into a Rain Gutter

How Flashing From A Shingle Roof Into A Rain Gutter Works

Last week we talked about the problems we often see with residential roof boots installed on low-slope or flat roofs, also known as commercial roofs.  That type of problem is almost guaranteed to leak, in time, so it’s kind of a big problem and we see it so often that we know it’s something that amounts to a significant cost the average building owner has to deal with.     Even though this issue is prolific and very expensive, it can actually be completely avoided, that’s why we feel compelled to educate people on the right way to do things related to proper building practices. Another significant issue that we see again and again is flashing missing between the drip edge at the low end of a roof or rear termination of a roof and the gutter. This type of issue can occur on true residential single roofs and also on flat roofs.

The picture below shows a pitch roof in Washington DC at a porch area.

This is a three-tab ceramic granulated asphalt shingle roof. The gutter at this roof carries the rainwater collected from the roof itself and also conveys the rainwater from the larger roof above which is run into this roof from a small downspout above.  Our pictures and discussion on this topic are related to our initial site consultation.   We later corrected some of these issues.

three-tab ceramic granulated asphalt shingle roof

The next picture below is at the bottom edge of the shingle roof from a lower angle so you can see that the top edge where the gutter terminates with a gap between the gutter and the lowest shingles. That open space is problematic for several reasons.   There should be an aluminum or similar impermeable material flashing between the shingles and the gutter. There should be no open space as shown in the photo below. Another issue, at this location is that the shingles themselves should be terminated at a metal drip edge instead of just having past been installed to pass beyond the edge of the roof sheathing. Sheathing and decking are basically the same thing, the words can be used as synonyms or interchangeably in many cases. Roof sheathing and roof decking are generally made from wood and are the boards or surface that the roof is installed on top of, as a proper substrate.

gap between the gutter and the lowest shingles

The next picture below shows the same location but with the shingles slightly lifted up so that you can see that the drip edge is completely omitted.

In other parts of our website, we talk about the phenomenon of capillary action and wind driven rain. All of these factors will cause water entry and or damage which leads to rot of building materials when items such as drip edges and flashing are omitted.

drip edge is completely omitted


Smart proactive replacement, construction, upkeep and maintenance of low slope roof systems requires an enthusiastic interest and understanding of waterproofing principles and building science.   Here in Washington DC, historic and modern residential and commercial buildings are extremely expensive and the roof and related systems provide the shield that preserves the building.

We encourage all of our clients, and all readers of this article and to our blog in general, to prioritize the value of quality construction and building maintenance, and develop a relationship with our company.  You can learn a lot more on our blog.  Feel free to check it out.  If you have questions about the roof and related systems of your building in Washington DC, visit our contact page https://dupontroofingdc.com/contact-us/ and drop us a line.  We will be in touch if we can help.

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