Install a Joist Hanger So It Actually Carries the Load

The Problem

A joist hanger transfers load from a joist into the beam or ledger it hangs from, anywhere wood meets wood without bearing underneath. The common install mistake is seating the hanger snug on one side with a gap under the other — the load lands on one edge of the bracket instead of spreading across it, and on a deck that's a structural problem, not a cosmetic one.

The Technique

1. Set the joist in place first, before the hanger. To hold it on layout without a helper: drive a screw through a scrap block, leaving it about 1-1/4" to 1-1/2" proud, hook the block over the beam at your layout mark, and land the joist against it. Drive one more screw to lock the joist while your hands are free.
2. Pinch the hanger's sides together just slightly before you offer it up. Sprung a hair narrow, it grips the joist and stays put on its own instead of dropping.
3. Slide the hanger up until its bottom sits fully snug and flush under the joist — no gap on either side.
4. Nail one side, then look at the bottom again and confirm it's still sitting flush before nailing the second side.
5. Nail off the remaining holes.

The little bent tabs ("dog ears") on the hanger are for the opposite sequence — tacking the hanger to the beam face first, before the joist goes in. Hammer them in to hold the hanger while you nail.