I bought a house with a 24x24' attached garage. The rafters above the garage has a cape cod style. There's already a door in the attic space leading to the outside (2 stories up with no staircase....) The previous owner told me he was planning to build an apartment space up there, complete with mini kitchen and bathroom. Seemed like a fun project for me to finish. However, looking at the garage ceiling it appears the joists are only 2x6s spanning 24' running parallel with the garage door opening, and I don't see how there's any center support. I can't fathom how the ceiling isn't sagging or how someone planned to build a whole apartment on top of that. Does this sound right to anyone?

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  • what sounds right? ... do you have a question about the structure? – jsotola Oct 31 '20 at 2:19
  • Can that span support a finished studio apartment? My understanding was you can't run a 2x6 over 11' max without some kind of additional support – Phaelax z Oct 31 '20 at 2:49
  • no, the 2x6 is just enough to support itself – jsotola Oct 31 '20 at 4:30
  • @jsotola How do you know the 2x6’s are not the bottom chord of the trusses? The op calls the 2x6’s “joists”, but obviously doesn’t know much about construction. When you said the 2x6’s are “barely enough to support itself”, what spacing, species and grade did you use? – Lee Sam Oct 31 '20 at 8:35
  • I call it joist, you call it the bottom chord, some call it a rafter tie. Doesn't mean I'm obviously ignorant about construction, but I'm no expert either. I just don't know much about trusses without some kind of support under it. I added some photos to the post and can tell you the "chords" are 24" OC. As far as type of wood and grade, I can't say for sure but looks like typical SPF lumber. Looking at it further, I suppose the floor is supported by suspending it from the rafters, but I don't know if that's good or not. – Phaelax z Oct 31 '20 at 12:59

My recommendation would be to consult a structural engineer or building engineer. They can tell you everything you need to know and also draw up plans for the addition so you can apply for a building permit if necessary.

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