What Changes
The top coat has to be UV stable or it ambers, and clear epoxy outdoors goes yellow reliably, so outdoor work is polyaspartic-topped as standard. The surface has to be non-slip while wet, because wet is what a patio is for a good part of the year, so aggregate goes through the top coat.
The build also has to move. An outdoor slab expands and contracts far further than a heated indoor one, and the system has to flex with it rather than crack. And the water has to leave: a slab that ponds will fail at the puddle first, so we check the falls before quoting anything.
Where It Works
Covered patios and porches are the best candidates by a distance, simply because they are protected from the worst of it. Beyond those it goes down well on front porch slabs and steps, three season rooms and enclosed porches, pool surrounds where the grip specification matters most, and carport slabs and walkways. Fully exposed open patios can be done, and we will be straight with you about the trade-off before you spend the money.
The Season
Outdoor work here runs roughly late spring to early autumn. That is not a scheduling preference. The concrete has to be dry the whole way through and warm enough to cure, and it has to hold both of those for the length of the cure, which a single warm afternoon in March does not deliver. Polyaspartic widens that window at both ends. It does not open it in January.