A Leak At A Rooftop Chimney – Part III


Last week and the week before, we took a look at a rooftop leak that was actually emanating from the location where the roof membrane terminated or bonded to the chimney. The connection point between the rooftop (roof membrane) and the chimney is usually terminated in a counterflashing or termination bar, but this leak was not actually related to the counterflashing, nor the roof membrane itself.

A link to those articles from the last two weeks follow below for reference.



Overall, our website and blog are focused on the principles of loose flat roofing and in some cases slate roofing and even shingle roofing as related to roofing principles, as is common in residential construction. Flat roofing, by comparison, is generally a commercial type product used on many historic rowhomes in Washington DC because of the configuration of original  construction.  Pitch roofs in close proximity, adjoined, or attached are required to share a demising wall that continues into the attic space and therein becomes less usable and harder to access in a rowhome type layout.

a leak at a rooftop chimney

Roofing contractors however are generally the only people up on a rooftop doing the type of routine maintenance needed to keep the overall roof system in good shape and working properly without causing new damage to the roof. Mechanical contractors are also often on rooftops because many rooftops in Washington DC have mechanical equipment installed on the rooftop, but they’re generally not charged with the responsibility or duty to conduct thorough care of the overall roof system.   In fact they often largely ignore the roof itself and just focus on nothing but the mechanical installation which happens to be installed on top of the rooftop. Often their work causes new damage to the roof membrane.

roof membrane damage

In the recent article, part two of this series, we showed a closer look at the mortar joints before removal of the defunct and deteriorated mortar at a nearby chimney in the same rooftop system, but in the picture below you can see the chimney at the same roof at the rear ell.   This chimney had also been scam pointed by another masonry contractor in recent years, but the work was completely ineffective and in fact the damage to the chimney was so extension from slow deterioration over time, that the bricks had actually be removed because they were loose to the touch. It was lucky that chimney was still standing.

scam pointed chimney

Once those loose bricks were removed, in order to be cleaned and have old mortar removed before being reset into the rooftop chimney, you can see the chimney flue exposed. Normally the chimney flue is completely enshrouded and encased with brick and not even visible below the chimney crown.

chimeny flue

Our company rebuilt the chimneys by reinstalling the bricks back in place in order to keep water out, not just at the chimney itself, but in the adjacent rooftop as well.

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, contact us or fill out the webform below and drop us a line.  We will be in touch if we can help.

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