Rooftop Chimney Crowns – PART II

Here are all the rooftop chimney crown basics – part II

At the later part of this past week we talked about rooftop chimney spark arrestors. Crowns are another common element of rooftop chimneys.  They come in a couple different shapes and forms but the most common is a 9″ x 9″ or 9″ x14″ terracotta flue tile. We looked at some of the different types of alternatives and discussed their manner of function and principles behind reasoning and applicability of use. 

Deterioration, Upkeep, and Maintenance of Chimney Crowns

This week, we are taking a closer look at deterioration, upkeep, and maintenance of chimney crowns with a focus into the type of damage caused by lack of maintenance and upkeep.

In the picture below there is a short rooftop chimney, in a larger modified bitumen roof system.  The counterflashing between the modified bitumen single-ply roof membrane and the base of the chimney looks suspect and unprofessionally completed, but the chimney crown looks like it’s even more improperly installed.

short rooftop chimney crown basics

Crowns are intended to grade water away from the chimney flue and onto the adjacent roof system.  From the roof system itself, water will be conveyed or carried away from the chimney and into a proper drain system, commonly with an internal drain at large commercial roofs or a gutter at the rear termination of urban DC historic rowhomes.

In this particular case though, the low point at the top of the chimney is inside of the border of the chimney itself and therefore will allow water to puddle and eventually leak down into the chimney interior.

voids in the gun applied sealant

Not only are there low spots identified by the arrows in the picture above, but at those particular locations there are even visually observable voids in the gun applied sealant smeared onto the area of the low spot or imposed valley of the chimney top.

reason for water puddle on roof

In the final picture below, you can see the same chimney top from a lower vantage point, from this viewpoint, the angle of the metal vent base is more apparent. You can see that angle tuns from the center of the chimney out to the exterior most brick, on the inside of the chimney area. This exterior brick creates a dam and will not let water escape by gravity alone. Instead the water will build-up there and puddle.  Unfortunately from that point water will invariably leak into the chimney and into the building interior.

chimney crown errors

How To Maintain Low Slope Roof Systems

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

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