Trent-Lion wrote:

The 13x15x9 ft. GH that I am restoring in North FL had a hard dirt
floor which drained reasonably well when open to the weather (GH glass
panes broken out)...

... I think I would like to cover
the entire floor with pavers....




You might consider leaving the walkways just a bit higher than the rest
of the greenhouse. The walkways tend to get compacted with use (and
therefore resist drainage), so starting with them higher will force
water to run to the uncompacted areas. Otherwise, the walkways will sink
a bit over time and water will collect there. You don't want to leave a
step up to the walkways, just tilt the pavers on the side so they slope
away. How much higher depends on the soil underneath and how much it is
likely to compact. My first greenhouse with a loam floor compacted
around 3". However, this was with just a woven poly weed block, so the
compaction was basically caused by foot traffic. The pavers will spread
the load out over a larger area, so the compaction should be smaller.

Two other possibilities: (1) you can take up the pavers and add more
sand under them if you do get compaction, thereby raising the walkways,
or (2) you can add a fairly thick layer of coarse sand for drainage
under the pavers when you install them initially. I would recommend 6"
for good flow. Of course that means you have to take out some of the
underlying soil (unless it's really sandy) or else you may have to step
up to get into the greenhouse.