I saw one of your other blogs on this interesting picnic table Ian and so I’m starting from the beginning. From a construction point of view this a pretty smart design which eliminates a lot of the cross bracing found in the usual designs.
I built a ‘regular’ picnic table for one of my sons 16 years ago out of Douglas fir. I didn’t use treated wood and it still looks almost like new to this day. It has been maintained well though with regular applications of outdoor oil finish and I think yours should do well too. Your main concern might be the laminated legs, but that might not be an issue with the right glue.
Mike, an American living in Norway