In the 60‘s a 2.5 car garage was added to my house, consisting of a flat roof that also serves as a deck. The original owner wanted to keep the garage free of any columns or posts, so the ceiling consists of 3x10’s, 12 inches on center.
That’s right, these joists are over 2.5’ thick, and, as it turns out, are about the same thickness as some engineered wood I-joists I’ve seen. The clear span of these 3x10’s is about 20’, more or less. One side is up on the sill plate atop one of the concrete walls, while the other ends are notched to accept a 1” thick ledger. Together, the joist and ledger are butted up against triple 3x10’s.
The joists themselves are not flexing at all. However, it seems that the ledger is beginning to pull out of its intended placement, causing each joist at that end to drop down. I would like to correct this, but are unsure how. I have found that hangers for those wood I-joist would probably fit, but they seem somewhat light duty. For one thing, we are thinking of enclosing the area above this garage as a room. I would prefer not adding any columns in the middle of the garage, but I am unsure on the modern code requirements for clear spans for room floors.