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How to ventilate a “room in the attic” truss system

Carl Mirabile | Posted in General Questions on

Hi. Building a two story small house – 28′ x 26′ in zone 4A, TN. Using a “room in the attic” truss system.

The trusses will be the 3rd story. The room in the middle will be 12′ wide and the length of the house, with a window at each end. The knee walls will be 5′.

I’m not sure how to ventilate or if it’s necessary. The 7′ on each side that will be behind the finished room. This will be the webbed part of the trusses.

Installing a metal roof, so do not want a ridge vent. Thought of soffit vents plus a gable vent at each end of the 7′ section, plus blown-in floor insulation. Other thought is seal it tight and don’t ventilate, it’s a small area and perhaps doesn’t need ventilation(?).

Any ideas would be appreciated.

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  1. Aj Builder, Upstate NY Zone 6a | | #1

    No contractor, no architect, no engineer, no codes? Winging it with internet questions?

  2. GBA Editor
    Martin Holladay | | #2

    First of all, metal roofs can include a ridge vent if you want one or need one.

    Second of all, your room in the attic will have sections of insulated sloped roof. These sloped sections of insulated roof can be either vented or unvented; your choice. To learn about all the different ways to insulate your sloped roof, read How to Build an Insulated Cathedral Ceiling.

    Once you have decided how you will be insulating the sloped section of your roof, we can discuss how to insulate the attic behind the kneewalls, and whether this attic needs ventilation.

  3. Stephen Edge | | #3

    There are many ways to do this. Need to know your ceiling height because and rafter depth. Also are you getting raised heels? I just did the same thing. Ended up making vents out of 1in polyiso from sofet to attic with roxul batts under that. Now I may fill the attic with cellulose. And put some xps or eps across the rafters on the sloped ceiling till I meet code. I will also put roxul batts above the plates filling the void to the rafters. I have a steel roof with a ridge vent and cottage cap. Be careful in your choices and keep asking questions.

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