Bonus room over garage

[JenMenden]

I'm trying to put a room over a garage on a one story house. I don't want a full second story and am ok with the pony walls that the roof will create. I cannot figure out how to do this. Any assistance?

[garyohmer]

build a second story over the garage then lower the ceiling down to what ever you want - built the roof -

[JenMenden]

do I derive from the 1st floor?

[garyohmer]

yes then lower the ceiling and add roof

[Bradley Boltz]

I'm trying to put a room over a garage on a one story house. I don't want a full second story and am ok with the pony walls that the roof will create. I cannot figure out how to do this. Any assistance?

How you do it depends on whether you will be framing the bonus room floor and roof system with Attic Trusses or via stick framed with rafters and floor joists. I believe that if you want to do it with attic trusses you may want to build the roof prior to creating the second floor.
You will have to raise your truss heel height to accommodate the 2x10 bottom chord, typical with attic trusses. You will then have to use raised heel trusses for the other parts of the house roof so that your eves align.
Once you've created your roof and second floor, you can adjust your ceiling height to 7'6" or 8' (can't be less than 7' by code-except can be lowered to 6'8" at beams (verify with whatever IRC code version for your jurisdiction).

If stick framing, then build your second floor and set your ceiling hgt to 1.5"(rafter plate that sits directly on top of 2nd floor joists) and build your roof planes. Once built you can re-set your ceiling height for proper head room and establish the bottom of your ceiling collar ties.-Brad

[perryh]

I raise up all my 2nd floor additions over top of the existing ceiling joists leaving a duct space of 7.25" by blocking up the new floor joists with a 4x8. Been doing it that way for 40 years now. I also allows you to put large beams in the floor system Also the existing ceiling is retained and people are not as disturbed by the building process. You also don't have to relocate electrical and gas lines with this method. It does add a couple of extra risers to the stairs. Framers love it. You can also do it with existing trusses. Set your floor joists along side of an existing truss nail the f.j. to the truss and cut off everything above it. Floor joists should be at 12" or 24" to align whit the trusses. When cutting trusses there are some patching to the truss needed to keep the integrity of it.