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Community and Q&A

A few questions on plenum trusses

Richard Riso | Posted in Energy Efficiency and Durability on

Some general info
20 x 35 house
Zone 4B
9 foot ceilings
Intello Plus Air Vapor Barrier.
Knauf Eco Fill Insulation blown into the attic space.
Truss length 20 feet, 12 inch raised heel. 7/12 pitch
Specific truss configuration
24 inch on center.
The 20 foot truss breaks down like this
6 foot then 8 foot plenum going up 15 inches then going back down 15 inches to the remaining 6 foot lenght on the other end, a total of 20 feet.

Purpose
To run ERV ducting and electrical in conditioned air space.
And Possible use within the plenum area the addition of insulation.

Questions
1) can I use plywood on the bottom side of the plenum to be part of the air barrier? That is 15 inches up inside the truss.
2) after running ERV Ducting and electrical can I do two things
First: Feel the plenum cavity with insulation.
Secondly: run a second air barrier at ceiling plane level to blow in the the insulation within the plenum cavity.

Your thoughts are appreciated.

Hope. these questions make sense.
Thanks Richard

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Replies

  1. User avatar GBA Editor
    Martin Holladay | | #1

    Richard,
    Q. "Can I use plywood on the bottom side of the plenum to be part of the air barrier?"

    A. Yes, as long as you tape the seams with a high-quality tape.

    Q. "After running ERV ducting and electrical, can I fill the plenum cavity with insulation?"

    A. Yes.

    Q. "After running ERV ducting and electrical, can I run a second air barrier at the ceiling plane level to blow in the the insulation within the plenum cavity?"

    A. Yes.

  2. Richard Riso | | #2

    Thanks Martin
    It is really great to have a source for some of our questions.
    Thanks again

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