Rooftop Air Exhaust Systems – PART II

In our last article, we started a discussion on Air Exhaust or vent and intake systems on roof tops.  Today we look at different examples and alternative types of installations of these systems.

This topic is part of a larger collection of articles on ferrous metals and associated problems in flat roofs.  

The outline of this series of articles follows:

    • Common types of non-roof components found or flat roofs
      • Access Systems 
      • Historic Brick chimneys
  • Air Exhaust systems
    • HVAC systems
    • Electrical power distribution
    • Low Volt and communication wiring and satellite / antennas
    • PV Panels and mounting structures
    • Guardrails and fall protection systems
  • Roofing problems caused by oxidation of ferrous metals
    • Delamination 
    • Staining and bondability
    • Structural component failure
    • Leakage through metals
  • Methods of Repair and sustainability 
    • Standard Coatings
    • Substrate preparation
    • Advanced re-coatings
    • Special roofing provisions

The picture below shows a solar powered exhaust fan used to bring hot air out of the attic and create cross-ventilation. This cross-ventilation and exhaust air helps in two very important ways. First, it can significantly reduce the hot building temperatures in the summer months. In this particular case we installed a new TPO or thermopolyolefin roof on top of this building. This roof has extremely high reflectivity and will reflect the majority of the sun’s ultraviolet and thermal rays which significantly increase the heat of a house in the summer. This exhaust fan also works to reduce moisture buildup and the potential for humidity in condensation within the attic. This is important because it reduces the moisture in the Attic which can lead to deterioration of susceptible materials, part of the building construction.

rooftop exhaust curb and fan

These pictures show the work in process of installation of the curb and fan. The solar panel on top of the fan provides all of the electricity required for the fan to operate. Interestingly, when the fan is needed most, during the summer months, the fan will run at a much higher rate. At that time, in the summer months, the solar power from the Sun is much higher. In the winter, that solar energy is much lower but coincidentally, the winter months require much less exhaust from an attic space. Also, these fans can work passively, whether or not they are actually spinning and operating, hot air can still exhaust through the openings underneath the protective rain cover.

installation of curb and fan

In our next article in the series we will look at different rooftop HVAC systems and how they interface with the roof membrane.

Smart and proactive replacement, construction, upkeep and maintenance of low slope roof and mansard roof systems requires an enthusiastic interest and understanding of historical methodologies, 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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