Best fix for failing built-in storage cabinet base?
I would say the best solution is one that gets the particle board monstrosities out of the house, but you probably want a best that's less extreme.
If this is just a trim board preventing stuff from rolling under the cabinet, replacing it with a trim board less subject to falling apart at any hint of moisture would be better. Vinyl trim boards would be arguably &quot;most durable&quot; in that sense, but painted solid wood (not particle board) will likely be fine if the water exposure is not extreme, and will be less expensive than vinyl trim (mostly intended for outdoor use) in my experience.