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Garage attic conversion

Eric_Indiana | Posted in General Questions on

I am looking to convert my garage attic space into livable conditioned space. My builder was very hesitant on doing that for me when we built the house, but I would like to do that in the future as the space is around 600 ft.² with a 10 foot ceiling at the peak. It appears that it was ran with 2 x 8, 16” spacing for the garage ceiling/the attic floor.  It is about 26 foot deep garage x 33’ wide with a large steel I-beam ran down the center. My question is will the current build support livable space?

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  1. user-2310254 | | #1

    Where are you located?

    1. Eric_Indiana | | #2

      Northwest Indiana

  2. user-2310254 | | #3


    Do you have mechanicals in the room or an egress in addition to the entry? It might help if you posted a couple of pictures.

  3. walta100 | | #4

    The first questions are structural.

    Is the 2x8 across the garage ceiling part of a truss supporting the roof above or was the roof stick built?

    Is the steel beam in the center sporting the 2x8, with 12 feet of span?

    If the roof /ceiling are a truss the best answer to your question would come from the engineer of the company that made the trusses. The next best answer for trusses is to pay an engineer to give you a stamped set of drawing telling you what need doing.

    If it is stick built you can measure the span and depth of the joist and look for a span chart on the internet. My gut says 2x8 spanning 12 feet will not meet code as a floor today.

    If you need a permit where you live you are likely to need stamped drawing to get it.

    In general the “bonus room” are not great living spaces with few if any windows and sloped ceilings. If you are lucky one wall will join a hallway if not you must add a staircase. The room is likely to need its own HVAC equipment. As there is general no good way to get large enough ducts into the space if the homes unit had enough excess capacity which it should not have.


    1. Eric_Indiana | | #5

      thanks for the responses.

      It is a full stick built home. The garage is 26x33 with the center beam in the middle of that span. So without measuring, I'd assume the 2x8 span is at least 12ft (maybe more?). The garage attic does have a static window, which would have to be swapped out to open, and there is at least 500-800 sq ft of useable space. The attic floor may level with the 2nd floor or a foot or two lower and the future door would either be within in a room, or the upstairs bathroom would have to be modified from a two vanity to a single vanity to install a door for the bonus room. I am just toying around with ideas as I wanted to add the bonus room when we built. The builder basically talked me out of it every way he could. Not exactly sure why..

      1. JC72 | | #6

        Rooms over garages are notorious for being drafty, cold floors, and suffer from noise/vibration intrusion due to the opening/closing of garage doors.

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