So water, rot and excessive stress? You must mean earthquakes, biblical floods and plagues of wood eating insects? It used to be so easy to just glue a few boards together........
If they are 4 inches wide and fairly flat even at 30% contact that's a lot of glue contact.
You could also drill right through the width of the assembled top a foot from each end and in the middle & install threaded steel rod with countersunk washers & bolts to stop it from even thinking of coming apart. I believe 24" drill bits are fairly common and sometimes they go straight. Now you only have to worry about the plagues of wood boring beetles; that's what I did .
Back to glue area, if you plane the boards flat before ripping, then rip, then glue, you get more glue area contact. Why? Because you just halved the irregularities before glue up.
Last edited by William Fretwell; 02-27-2018 at 10:29 PM.
You can do a lot with very little! You can do a little more with a lot!