Very nice looking project, Russell.
Next time, though (if you don't mind a little criticism)-- I would not use the "standard" beech Dominos, but instead use the sipo ones made for exterior use. The Sapele you used can handle outdoor exposure, but I've seen many pieces of outdoor furniture fail at the joints when an inappropriate specie was used there.
Moisture has a way of finding its way into the joints and allowing fungus to grow and rot out the wood inside the joint. Hope your piece does not suffer this fate!
I don't disagree that Beech will not suffer moisture damage more greatly than a Sipo...We are on the same page with that observation for sure...
With the "toggle tenon" (aka Domino) being encapsulated within aliphatic resin (which will not stop moisture from getting into the joint)...but more importantly!!!
...will greatly slow the joint from drying out between wet weather events...this may even be more of an issue...in some cases, but not necessarily this one?
I suspect that Russell knows all this already, and made a logistical/fiscal decision based on budget and durable life span?
Out door (aka exposed) furniture has a life span...It's that simple. With the species he selected, and the finishing method as described, along with the recommendation to the client on proper maintenance annual maintenance, I still believe (from my experience) that they will get a life time of service from what he built...perhaps even longer...???
I make this observation, from building similar with species like White Pine, and other much less durable wood. If well built, and seasonally "oiled" (I use Heritage Finishes and have for 30 years...which is similar to Watco but with more traditional elements in it) getting a life times service from such projects is more than achievable.
Where we differ...
1. I do not use adhesives...at all...(or extremely rarely?) with outdoor furniture and/or structures like my timber frames that are exposed. They trap moisture and promote decay...even in woods like Sipo and other "rot resistant" species.
2. Joinery should be designed and made to "drain water" wherever possible. This is usually not that difficult to do.
3. Tension joinery whenever possible (aka wedges, gravity joints, draw boring, etc.)
4. Traditional treatment elements for the joinery...e.g. copper shrouding, "salting pockets", etc.
5. Seasonal or bi seasonal (depending on location) with a good broad spectrum tradtional Oil, Resin and Wax finish that also has UV and mold inhibitors added...
Those five will keep a piece even made in a conifer wood species lasting much longer than just one generation and or very easy to service if it does need to be...