Can the H1Z (diamond shaped) hurricane clips be installed on the inside of a wall's plate or do they have to be on the outside?
H1Z clips, per the manufacturer, belong on the outside with the "ears" facing outward (not resting on the top plate).
The purpose of having the clips on the outside are twofold:
- So the clip is attached to the rafter tail rather than the ceiling joist
- The rafter board and the ceiling joist could become separated in high winds
- If the rafter board is held down, it will hold the ceiling joist down as well
- So the upward force on the roof does not cause the top plate to pull away from the walls.
- If the clip is on the inside the, only thing holding the top plate on securely would be drywall (or often nothing in the case of an unfinished garage). The wind could "bend" the sheathing and easily break it due to the angle of force.
- However, if the clip is on the outside, the sheathing will keep the top plate from separating because the sheathing would hold it down where the clip is. Any upward force would be fighting against the sheathing whereas on the inside, it would have just been fighting against drywall or some nails.
With that said, if you put the clips on the outside of the wall (under the sheathing and above the soffit), an inspector may not be able to see that they are installed. Some inspectors might prefer them on the inside for that reason.