Framing in a storage loft in my garage

[Cdshakes]

I have a 1950's cape with an attached garage (not original to the house).  
I have my shop in the garage and desperately need some storage.  I am thinking about adding a loft over the dead space above the garage door.
The walls in there are pretty high-- about 10 feet or more.  The width of the garage is about 11 feet.  I was thinking about putting rafters side to side about half way back and then some flooring on top.  Is standing up some 2x8's on top of the double plate and nailing to the adjacent stud sufficient?  I was looking at some where they nailed onto the outside of the plates, and some where they used joist hangers.  Is any of this needed when it's just storage (not a live load)

Colin

[K. L. McReynolds]

Use joist hangers and 1/2" OSB for flooring. The 2x8's will stand proud of the hangers.

If you make the loft deep enough, you will need to get up there to arrange the storage.

[Cdshakes]

where should i attach the hangers?  right to the double plate?  or should i put up a  2x8 to the wall to hang them on?

[Splinter Puller]

either will work.  A ledger will let you have the joist lower then if you use the plate.

[crokett™]

If you have access above the top plate, I'd run the joists to rest on the top plate if you can afford to lose the 7.5" of headroom.  If you don't I wouldn't hang joist hangers for 2x8s directly to the top plate. a doubled top plate is only 3" high, a joist hanger for a 2x8 is taller than that. The bottom sets of nails won't be nailed into anything. I'd bolt band joists to both the top plate and wall studs, then put the joist hangers on that.

[Lynden]

If you have access above the top plate, I'd run the joists to rest on the top plate if you can afford to lose the 7.5" of headroom.  If you don't I wouldn't hang joist hangers for 2x8s directly to the top plate. a doubled top plate is only 3" high, a joist hanger for a 2x8 is taller than that.  The bottom sets of nails won't be nailed into anything. 

Simpson makes a top-flange joist hanger (LB28) which doesn't require nailing below the double top plate. Wouldn't this type of hanger work? 

https://www.strongtie.com/topflangehange...z.ba.b.hhb (scroll down for tables)

http://www.homedepot.com/p/Simpson-Stron...mpson+lb28

[Splinter Puller]

I'd also consider a ledger installed on the walls supporting the bottom of the new joist.  This will save the cost of pricey hangers.   I'd follow up with blocking between the joist to keep them from racking as they sit on the ledger.

[Pirate]

I would put in a ledger board (2x4) on each wall with a jack stud under it at each point that supports the joists.
Ledger board to wall studs with long lag bolts.

[crokett™]

Simpson makes a top-flange joist hanger (LB28) which doesn't require nailing below the double top plate. Wouldn't this type of hanger work? 

https://www.strongtie.com/topflangehange...z.ba.b.hhb (scroll down for tables)

http://www.homedepot.com/p/Simpson-Stron...mpson+lb28

Yeah that would work fine.  I actually added "if they make a hanger with a top flange I'd use that" then removed it.  

[geek2me]

 I am thinking about adding a loft over the dead space above the garage door.

...
 I was looking at some where they nailed onto the outside of the plates, and some where they used joist hangers.  Is any of this needed when it's just storage (not a live load)

First thing to determine is whether the walls and support are rated for any additional load - usually they are not.  You are proposing to add a significant dead load.  If the building does not have the structure to support that, you risk collapsing the building, a much more expensive repair.

Best to have a PE look at it - and you will probably need stamped drawings for the building permit anyway.