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Community and Q&A

Ventilating Stairways in Multifamily Buildings on the Cape

jklump | Posted in Mechanicals on

I am renovating a five building development in Orleans, MA that includes a new envelope (windows, added insulation on the exterior and new siding). I am also planning to add fresh air to the small (2 stories) stairwells in each building. Should I be concerned about humidity so much that I add a cooling system as part of the ventilation? There will be continuously running bath fans in each unit and existing through wall AC units. I don’t want to overdesign for a few days a year that I might generate condensation because I am not cooling the make-up air.

Thanks for any help.

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  1. GBA Editor
    Martin Holladay | | #1

    You are concerned about condensation. Where? If you introduce warm, humid ventilation air during the summer, the moisture in the air won't condense unless it hits a cold surface. Is there a cold surface in these stairways that you are worried about?

  2. jklump | | #2

    The doors have painted metal frames.

  3. GBA Editor
    Martin Holladay | | #3

    And if you aren't cooling the stairways, how will the door frames ever get cold enough during the summer to allow condensation?

  4. jklump | | #4

    The apartments will be cooled to maybe 72 at the lowest. I don't want to add cooling to the stairway, it seems like a waste. I just want to add fresh air to the stariways and pull it under the doors due to the continuosly running bath fan in the apartment. I have been told to add cooling to dehumidify the warm air I am bringing in the summer.

  5. GBA Editor
    Martin Holladay | | #5

    I seriously doubt that the metal jambs of interior doors will ever get cold enough to permit condensation under the conditions you describe.

    However, the tenants may prefer the stairway to be cooled during the summer for comfort.

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