Drawing parallel rectanges

I am trying to design the framing for a shed floor.

Assume a unit is 1"

I am trying to draw parallel 96"x3.5" rectangles that are 16" on center.
I have tried snap to distance,  but the copied rectangle does not snap 16" to the right of the original rectangle.
It snaps everywhere else (above, to the left).

What is the best way to achieve this?

Thanks in advance

What does "that are 16" on center" mean, distance on axis?
If you want to use "Snap Distance", you need to draw a baseline first. It doesn't snap into nothing, only on an entity.
Better use Modify - Move/Copy and the command line. Specify reference point: select a corner of the rectangle with mouse.  -  Specify target point: @16,0   Enter.
You can even make multiple copies then.