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Chimney Enclosure – Above Roofline

Jeremiah_Sommer | Posted in General Questions on

Hello GBA, looking for some advice on the exterior portion of a chimney enclosure. 

Project details 
-certified wood burning fireplace 
-insulated chimney pipe 
-all clearances have been met 

We recently conducted the above roof decorative portion of a chimney enclosure. The enclosure was framed with standard dimensional lumber, sheathed with plywood and detailed with a robust WRB.

At the ceiling level we will be paying extra attention to air sealing around the chimney support collar as we are targeting <1.0 ACH @50 for this building enclosure. 

Even though the pipe that extends through the roof will be insulated, I imagine that there will still be some, albeit minimal heat that comes off the pipe. Which makes me wonder about the potential for condensation to form on the inside of our plywood sheathing. We will be using a rainscreen system before installing our cladding which will permit drying to the exterior. Another option would be to install insulation on the outside of the enclosure prior to the rainscreen however I’m debating how necessary this is. 


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  1. Expert Member


    It's fine. Any heat the chimney throws off is a good thing. It will help dry out the chimney enclosure. It isn't heat that causes condensation.

    1. Jeremiah_Sommer | | #2

      Thank you Malcolm, that’s totally logical. My priority is making sure the exterior is properly detailed to manage bulk water and that air leakage from interior is cut off.

      1. Expert Member
        MALCOLM TAYLOR | | #3


        Good plan. My experience with those chimney enclosures is they usually fail because they were thrown together. If you spend a bit of time on them, they should last quite a while.

        1. Jeremiah_Sommer | | #4

          Agreed, we rarely build these enclosures. Typically we recommend simply exposed SS chimney pipe. Simple to install and maintain with minimal detailing beyond the storm collar.

  2. Uiloco | | #5

    Consider adding exterior insulation before the rainscreen to prevent condensation and improve thermal performance. It's worth it for colder climates. Follow the manufacturer's recommendations for safety and efficiency.

    1. Expert Member
      MALCOLM TAYLOR | | #6


      I don't know if this is spam or just poor advice.

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