"The key thing to remember is that you must not apply glue to the dominos (or biscuits). If you do this then movement across the grain (which will happen) can cause the joint to fail. This happens because the glue in the domino prevents free expansion and contraction along the region of the joints. The dominos do not expand and contract along their length and so will have to try and move relative to the wood that they are in. Better to let them do this by not having any glue there."
No offence, but this is not right. There's no way a loose tenon, biscuit or dowel will stop a board from moving seasonally.
No offence, but this is not right. There's no way a loose tenon, biscuit or dowel will stop a board from moving seasonally.