I've used beech dominos for outdoor projects and had no problems, simply because the beech domino is surrounded by the timber to which it is inserted into and a D4 type waterproof glue is used. imho I don't see a problem here and as you mention if the joint is well made, a decent glue and well protected by the finish.....................srp":2l2e9lq6 said:A frame will (99% of the time) fail because of water ingress at the joints first. Beech is not a durable wood by any means, so the standard doms will rot out in no time once they are wet, long before the surrounding timber. It's not difficult to make your own from redwood or iroko, though they do need to be accurate. I made some for a bit of marine work from iroko - it doesn't take long to plane up some strips and snip them off on the bandsaw.