In order to ensure a dry townhouse for years and decades, one has to properly detail roof connections so that there are at least 2 different systems in place directing running water away from the home. Here we examine the often overlooked townhouse gutter system which is typically slapped on the back of the house and glued in place.
To ensure there are no leaks, if your new copper gutter fails, one must clad the roof structure and part of the masonry beneath the gutter with rubber (or other) roofing membrane. This ensures if water dams up, or freezes, that any penetrating water will make its way back to the exterior of the building envelope. Further, the gutter itself is supported by copper flashing trim to help support the gutter so it does not sag in the future, thus preventing ponding, mosquitoes, rust or freezing. The trim also acts as a slope guide to ensure the gutter gently slopes towards the downspout, as noted in the elevation diagrams.
Once the gutter system is in place the rest of the roofing membrane can be installed, to create an overlap of membrane allowing water to flow downward without interruption by seams.
While installing a gutter properly will cost more, it will ensure a trouble free home for 40 or more years. Installed incorrectly expect to have issues within a few years, and leaks around 10 years, leaks that could run down inside the stud wall cavity for years before discovery, often the source for that mildew smell in the cellar.