Q: How do I fix the 1/4-inch joint that keeps opening up between my laminate countertop and backsplash?
The laminate countertop in my kitchen has a separate 4-inch laminate backsplash attached to an exterior wall. There's a 1/4-inch joint between the two surfaces, which I've caulked a couple of times, but unsightly cracks still open up. How can I fix this?
—Patricia Smith, Hartville, OHIO
Tom Silva replies: What's happening is that the backsplash is moving independently of the countertop, not uncommon when a backsplash is attached to an exterior wall. A 1/4-inch gap is a little too big for caulk to hold. Here's a way to make it smaller.
First, cut every bit of old caulk out of the joint with a utility knife and scrub both sides clean with an abrasive pad and dish soap. Wipe the surfaces dry and run a strip of painter's tape along each side of the gap to prevent new caulk from smearing on the laminate. Now look inside your cabinets. At the back, just under the countertop, you'll find a mounting rail or corner brackets with screws that hold the countertop in place. Back them out temporarily.
Stuff a foam backer rod into the joint between the countertop and the backsplash, then cover the rod with an acrylic caulk. If you want, use a colored caulk to match the laminate.
Next, push some wood shims between the the underside of the countertop and the mounting rail or the top edge of the cabinet. When you've reduced the gap to about 1/8 inch, re-attach the screws, but don't tighten them all the way-they just need to be snug. Finally, wipe off the excess caulk and remove the tape.