How high above the floor of the garage to the new floor height?
It is chancy to support anything off the garage slab because it can move You could look at TGI floor joist that might span the 20 ft then you could figure out how to support that where there is a foundation. Assuming there is a foundation around the outside?the top of floor needs to be at 25 inches to be even with the existing structure.
16 ft is pushing you luck with 2x10sProbably easier and more economical to do the knee walls on each side and one in the middle, then you can use smaller joists and rim boards, which you don't have to worry about attaching adequately to the existing walls. According to these span tables, even select structural 2x10's at 12" spacing won't quite get you to a 20' span. However, grade #2 doug fir 2x8s (which are readily available and far less expensive) at 16" spacing (or even 24") will span 10'.
If you don't want to build the knee walls, a 16" TJI joist gets you very close to your desired height with the 2x8 joists (24.25" with 3/4" subfloor).
16 ft is pushing you luck with 2x10s
So you would put the whole floor on a garage floor?
...span 2x10s 12 feet to the center.
Have you got any experience with 20 or 24 ft 2x10s. I do and I can tell you, not a chance in hell.According to the span tables I posted, you can span over 12' with #2 Grade 2x8's at 16" spacing using any of the common species used for lumber of that size. 2x10's at 24" spacing would also work, but an 1 1/8" subfloor is typically recommended for a 24" joist spacing.
I haven't tried handling something that size, but I know I wouldn't want to. I certainly wasn't suggesting that he use them, either, if that's what you're getting at. My suggestion was to use 10' 2x8's (at 16" spacing) with blocking at the center support. The OP suggested he would rather span the other direction in the room, so I suggested (or meant to suggest) 12' 2x8's (still works at 16" spacing). Since he seems to be partial to 2x10's, I mentioned the option of using 2x10's (presumed he'd be use 12' lengths, again with blocking at the center) at up to 24" spacing.Have you got any experience with 20 or 24 ft 2x10s. I do and I can tell you, not a chance in hell.
nice adviceProbably easier and more economical to do the knee walls on each side and one in the middle, then you can use smaller joists and rim boards, which you don't have to worry about attaching adequately to the existing walls. According to these span tables, even select structural 2x10's at 12" spacing won't quite get you to a 20' span. However, grade #2 doug fir 2x8s (which are readily available and far less expensive) at 16" spacing (or even 24") will span 10'.
If you don't want to build the knee walls, a 16" TJI joist gets you very close to your desired height with the 2x8 joists (24.25" with 3/4" subfloor).
So here is the rough sketch of what is going to be happening. The garage is currently on a slab that has footings where it conects to the house and the rest is foam wall frost protected as i live in Wisconsin. Im just looking to do the garage remodel framing to save some money as some of the early bids push our budget way to much. However why i have framed walls in the past for garages i havnt done floors.