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Community and Q&A

Insulating and Air-Sealing Ballon-Framed Brick Duplex

DarwinS | Posted in Energy Efficiency and Durability on

1910 Detroit Duplex

I am renovating a 1910 Detroit duplex.

It is an up/down duplex built in brick and I am told “Ballon framed,” on the interior 2”x4” walls. The framed walls don’t contact the exterior brick walls and are sheeted diagonally with 1”x8” boards. On the exterior of the exterior sheeting is black tarpaper. Between the tarpaper and the brick is about a 1”gap. 

I want to insulate the home and make it as airtight as possible. My plan is to spray foam the rim joists in the basement, spray foam and air seal the attic floor. What I don’t know is: 

  1. Should I spray foam between the studs 2” and fill the rest with bat insulation? (I am afraid this will make the 1”x8” sheeting condense water in the summer and it will not be able to dry to the interior because of the spray foam.)
  2. Should I fill the stud cavities with dense packed blown in insulation, drywall over, air seal and paint? (Will the insulation just suck up the moisture and cause other problem?)
  3. Another plan I have not thought of? 

The brick is in great shape and the house has large overhangs with new gutters keeping water off the brick. Further I ran all the downspouts into 4” pipes and released the water at the street. 

Any guidance will be very appreciated! 

Darwin Spaysky

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  1. Walter Ahlgrim | | #1

    Is the plaster/drywall all been or going to be removed?


    1. DarwinS | | #3

      Everything has been removed (plaster,) and I am at the stage of insulating.
      Thanks for the reply!

  2. Expert Member
    Akos | | #2

    I own a similar place and did SPF for the rim joists in the basement, installed blocking at each floor, the end of each floor joist and at the top of the balloon framing bays in the attic. The walls were than dense packed with cellulose. The dense packing does a good job of limiting air flow, the place went from [email protected] to 5.

    SPF in the walls also works, it won't create issues with your sheathing as the boards can dry towards the exterior through air gap behind the brick.

    When insulating these old houses, it is also important to fix your window/door flashing details. These tend to be non-existent and bulk water leaks there will turn your insulation into a moldy mess in no time.

    Insulating any brick house is always a bit risky as the bricks will now be significantly colder, I would check around the neighborhood with similar vintage brick houses. If you see a lot of spalled brick, you might want to limit the amount of insulation you add or stick to air sealing only.

    1. DarwinS | | #4

      Great information; thanks for the reply!

      All the houses around that have been kept in good repair the brick are looking good. I think I will flash and batt the walls.

      You did a great job of reducing the air flow on your project. I imagine the house was noticeably less drafty and comparable. Again thanks for the reply!

      Also, how did you insulate the attic?


    2. Deleted | | #5


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