Debate: Should you caulk gaps in trim or leave them for expansion?

I got into it with a finish carpenter named Dave on a job site in Nashville last year. He swore up and down that caulking every seam between baseboard and floor is asking for trouble in humid months. Said the wood will move and crack the caulk, making you redo it every season. But my argument is that leaving gaps looks sloppy and collects dust like crazy. I've seen houses six years old with no caulk and the gaps are big enough to drop a dime through. Dave said he'd rather have a clean gap that stays the same than a messy caulk line that fails. Who's right here? Anyone else dealt with this call on a finished house?

2 comments

2 Comments

the_lucas12d ago

Good point about the shoe molding, Gavin. My uncle built houses in Charleston for thirty years and he swore by quarter round for exactly that reason - it lets the baseboard sit still while the floor moves underneath. He'd say caulk is for hiding a mistake, not fixing one. I've seen those caulk jobs fail too, especially in houses with hardwood that swells in spring. The caulk gets this crusty look like old toothpaste. If you're gonna skip shoe molding, I'd rather see a consistent 1/8 inch gap than a caulk line that's cracking after one humid summer.

carr.gavin12d ago

Dave's got a point about wood movement, but it depends a lot on the gap you're talking about. Baseboard to floor? That should have shoe molding or quarter round, not caulk, unless you're dealing with a floating floor that needs that gap to breathe. Caulking baseboard to floor is just asking for trouble because the floor and the baseboard move in different directions. I've seen caulk hold up fine for years in trim corners where it's wood to wood, but floor to base is a different animal. The real trick is knowing when to caulk and when to let it be, not just covering everything up.