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Attic insulation question

Brian Ducharme | Posted in Energy Efficiency and Durability on

I am starting framing on a new house this week and I am still trying to work out a few details. The house is a cape-style design. I know this creates a less than desirable situation for insulating and installing mechanicals but I am trying to work through these issues. My current plan was to install closed cell insulation in the sloped ceilings. I recently decided to install the closed cell right to the ridge of the house as this would allow me to create a more efficient forced air system. I have a well-used layout which doesn’t leave much room for a duct chase. I was going to install one unit in the basement and one in the attic as well as the attic unit would be within the thermal envelope.

My newest concern for this method is with my radon system. By code I am required to install the piping for my radon system through the roof. I recently read Martin’s article stating you do not want the radon fan within the conditioned space of your home. This now makes my idea of insulating to the ridge unfeasible. Has anyone run into this issue before? Should I just try to find a location for the duct chase somewhere and forget the idea of insulating to the ridge/installing a second furnace up there? Is there another way to make this work?

Any thoughts would be greatly appreciated.

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  1. GBA Editor
    Martin Holladay | | #1

    Two points:

    1. I advise you to start with a passive radon system. In many homes, that's all you need. The fan used for an active radon mitigation system may not be necessary.

    2. If testing shows that you need a radon mitigation fan, it can be installed above the roof (see photos below). Plan ahead by talking to your electrician.


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