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Air-Sealing Between Second Floor and Attic

iainb | Posted in Energy Efficiency and Durability on

I’m working on doing some air sealing in my home to get better comfort and efficiency. There are more (an bigger) difficulties than this one, but I have to start somewhere.

I want to air seal between the second floor and the attic. There are a total of 7 fixtures, two bathroom fans, and one pull-down stairs hatch. The attic itself has a floor over most of it. with insulation between the floor and the ceiling. It goes from gable end to gable end, but is a couple inches out where it goes under the rafters.

Here’s my question: should I air seal the lights from the ceiling side or is it worth taking up the floor to air seal from the attic side? I had to tear up part of the floor already to repair an electrical problem, so there’s already work to be done.

To complicate it the ceiling joists are perpendicular to the rafters. I *think* the floor is acting as the brace to stop the walls from spreading, but I haven’t had a chance to dig in around the edge to really determine the exact framing method they used.

Any advice is appreciated.



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  1. GBA Editor
    Kiley Jacques | | #1

    Martin Holladay gives a solid overview of how to approach it in his article Air-Sealing an Attic. The hatch is the biggest leak and trickiest to detail. Here’s one of a couple articles we have on the topic: How to Insulate and Air-Seal Pull-Down Attic Stairs.

    1. iainb | | #2

      Thanks. The pictures in the air sealing article *imply* that the author preferred to take up the floor. So I guess I'll take that approach.

      I was anticipating the attic hatch being a pain because it's not closing perfectly and it's a pull down stair case not folding so I can't just build a box on top of it. I have to air seal the hatch or replace the stairs.

  2. Andrew_C | | #3

    If you can pare down your belongings such that you don't have to store anything in the attic, air sealing the hatch is relatively easy: just caulk it shut. If you only go up there every couple of years for (?), you can just cut the caulk with a utility knife and re-caulk it when you're done. You'll still need to insulate the attic hatch.
    And thinking about it, if you don't need to use it regularly, you could remove the pull-down stairs and just have a plain hatch, which would be much easier to insulate.

    1. Expert Member
      MALCOLM TAYLOR | | #4


      Agreed. The ideal solution is to remove the hatch altogether and access the attic from a gable end.

    2. iainb | | #5

      Well, it's a 7.5' ceiling so getting up there when I have to wouldn't be too bad with a ladder I guess. I don't use it for storage now, but I'd like the option of making it conditioned storage space at some point, and having it available for ducting for an AC install. But that's not immediate.

      Does a window in the gable end count as access (I joke...mostly).

      1. Andrew_C | | #6

        Emergency and escape rescue openings shall have a net clear opening of not less than 5.7 sq. ft. The net clear opening dimensions required by this section shall be obtained by the normal operation of the emergency escape and rescue opening from the inside. The net clear height opening shall be not less than 24" and the net clear width shall be not less than 20".

        But, filed under do as I say, not as I do...if you don't need the storage at this point, the goal is to never expand because you need to store more (stuff). Especially conditioned space, as both your short and long term costs go up. I'm sure you've heard this before, but I just finished moving my parents so it's fresh in my mind. Too many things. I spent time this past week starting to go thru my own detritus. Again.

  3. walta100 | | #7

    Would I be wrong in guessing your house is 1 and a half stories?

    If so, air sealing your home from the attic is next to impossible.
    I hate spray foam and conditioned attics but if you will not sell this hateful type of building and insist on spending money to improve it seems to me it is your only real option.


    1. rondeaunotrondo | | #8

      Jeez Walta, calling my home hateful! :) It is a real PITA. No way around it but if we are attempting to reach carbon neutrality we will need to retrofit 1.5 level homes too.

  4. walta100 | | #9

    Sorry Will.

    Yes I lived in a old story and a half house once. The experience left me with strong feeling about that style home.

    Consider by the time you have retrofitted an old 1.5 story home to modern air leakage, insulation, plumbing and electrical standards there will not be any original surfaces in the building and your costs will be above new construction.

    From a dollars and cents point of view selling the house as is now without spending tons of money trying to make the house be high performance and mostly failing seems like the smart move.


  5. iainb | | #10

    Thankfully it's a full two story colonial revival, 1938. So I have plenty of room in the attic to work with. There are some other ugly problems I have to deal with, but one at a time.

    I'm aiming for comfort here. I don't think high performance is in the cards without spending 6 figures. I'll settle for comfortable and efficient enough to run off an air source heat pump at some point. Which I think is doable without breaking the bank.

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