Caulking should have been used. Home Depot just subcontracts local guys.

Any time you have a change in planes, grout caulk should be used.

Home Depot subs out; no guarantees their subcontractors follow best practices.

Thank you both for the quick reply. I will reach out to Home Depot to see if they can send someone out to remove the grout and apply grout caulk instead (hopefully this is still covered under warranty). Is there anything I need to look for when purchasing grout caulk? Are there different types?

You'll want kitchen/bath caulk that is waterproof. Comes in colors or clear.

Michelle misses Sophie is right. That's what I meant.

Thank you all! Is this the correct product? https://www.homedepot.com/p/Custom-Building-Products-Polyblend-381-Bright-White-10-5-oz-Sanded-Ceramic-Tile-Caulk-PC38110S/202520295

That's the stuff, but probably unsanded for that tiny joint.

I believe the grout they used was sanded-- does that matter if I go w/unsanded for the grout caulk? I found unsanded by the same brand in the same color. Thanks again; this community is so helpful. :)

No one gives more than a 1 year warranty. This is your DIY project, not HD’s.

Scrape out the old grout with a 5n1 paint scraper. Get a caulking gun. A good one. One that releases pressure when you stop squeezing. Tape it off with blue tape. Squeeze out a thin bead. Spray with windex. Run your finger along the bead. Remove the tape. Done.

Even when one uses the correct product, the movement between planes can cause that area to crack over time. It is my DIY project soon too, and I used the right product the first time:) I am waiting till winter when the crack is at it widest.

100% Silicone Caulk period. GE Silicone II is a solid choice.

Live_Wire_Oak - I am thinking of doing a similar project, but mine is for 12-or-so-year-old caulk that is just needing a refresh due to age. Why Windex? I thought you spray with water at that point.

Windex is a bit slipperier. You’re less likely to have a finger go through the liquid film and catch the caulk. Soapy water will do the same thing. But most people already have a Windex bottle under the sink.

following

You place a continuous shim the thickness of the grout lines on the leveled countertop and tile on top of it. Grout the splash, pull the shim, and pump the gap full of 100% silicone color matched to the grout. Spray it with Windex, spit on your finger, and tool it to perfection. Wipe off the Windex overspray before it dries without touching the fresh caulk. That bead will flex with building movement, look good for years, and is replaceable if need be.

The pictured gap between the deck and tile is too small; it may never behave or look right even after the grout is replaced with silicone.

HD has agreed to send someone out free of charge to fix the issue since the incorrect material was used. :)