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Finishing an unfinished attic space

Hello all,
Just starting to get ideas to finish our attic space. There are no ducts run and we have forced air in the finished portion of the house. We live on the west side of Michigan and do get pretty cold winters but also quite hot summers.

Right now it's separated from the main living space by a sealed door and could remain that way if we wanted to go with a different heating system up there. I'm not at all opposed to being able to shut that area up when not in use. Nothing is finished including floors or walls or insulation so all of that could be tailored to the heating system. I'm wondering if it makes sense to wait until we need to replace the main furnace and then have ducts run to the upstairs as well as purchasing a larger furnace to service both spaces or if using an alternate method for the upstairs would make sense. Note the joists run across the width and not down the length of the house so you couldn't run a duct all the way down the length in the floor.

Also cooling is it consideration but again the air conditioner would be underpowered for both spaces together as it stands. I guess I'm just hoping for any thoughts on alternate ways to do it or whether or not those ways are just not worth messing with.

Thanks for your consideration


  • Jamie Hall
    Jamie Hall Member Posts: 19,401
    Got a handy dandy gable end wall in there? Go with a mini-split heat pump/air conditioner. Mount the interior head on that gable end wall, and put the compressor etc. outside somewhere.

    Insulate the dickens out of it all...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 9,906
    Two floors.....2 separate systems.
    Every attempt at using a basement furnace to heat and cool the second floor is a halfa$$ compromise. I have tried it, seen it and tried to fix what others have done.

    In the end it is just barely tolerable.
    Often see a window AC added on the second floor after these attempts have been tried.

    The idea of the Minisplit as suggested by Jamie is my thought.
    Although, because of where you are located, you might need supplemental heat.
    Such as electric baseboard heaters. The Minisplit heat pump will claim to provide all the heat needed. It might, depending upon your insulation and air tightness for your room. But IIWM, I would make provisions for the electric heaters. Just get the wire there, you can add them later if needed.
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,629
    Hi @Dorcaszmeatbone , I agree with the above. Also, I suggest having a look here:https://www.buildingscience.com/document-search and searching for "attic conversion". See what ideas come up.

    Yours, Larry