Actuated Rooftop Chimney Caps

The basics of actuated rooftop chimney caps

In previous blogs we’ve discussed chimney crowns, particularly above and associated with low-slope or flat roofs in Washington DC.  We’ve even briefly touched on the concept of actuated caps to work and function as rooftop chimney dampers. Most commonly, the dampers at fireplaces in chimneys are installed down at the fireplace itself at the top of the fireplace or firebox, but there are alternative methods of installation and one of those methods is to install the damper integral or connected to the cap, above the roof or rooftop of the building, so that it can be controlled and actuated with a cable down at the firebox location or in proximity to the fireplace itself.

Why Are Actuated Rooftop Chimney Caps Installed?

This alternative and slightly less common type of installation may actually perform slightly better in some ways.  An actuated cap above the rooftop basically seals the length of the chimney off from animals and the exterior elements.    Even when an actuated cap is not installed, a spark arrester should keep animals out of the chimney. However, A chimney can be very cold in the Winter at times when it’s not in use. If that chimney is as old as a historic building, it may have significant air leaks which allow air to enter from the outside in through the chimney and into the building.

actuated rooftop chimney caps

Like a typical chimney, this historic chimney’s main purpose is to convey and vent air and fumes from the fireplace to the rooftop termination.  As this portion of the chimney is above the roof line, the crown, cap flaunching, exposed brick, and roof counter flashing are required to keep out weather and elements. In the case of a typical cap and spark arrestor, these parts also needed to keep out rodents. Unlike a typical spark arrestor though, this particular style of cap lacks an integral spark arrestor and the spring frame used to articulate or open the actuated damper is large enough to allow rodents to enter. 

Dangers of Improperly Installed Rooftop Caps

rooftop caps dangersAlso, this particular cap, as it is surrounded with large openings between the spring frame, has openings that are too large to keep sparks from blowing into other parts of the building from the rooftop chimney or other adjacent buildings where combustible materials may catch fire.

length of rooftop cap

The chimney itself isn’t a direct part of the roof but the roof, especially in this case adjacent to a single ply modified bitumen roof membrane, is important and integral as the chimney ties into the roof and requires proper flashing. If the chimney were to leak, these elements deteriorate and become integral with the roof itself.

How To Maintain Your Roof

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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