I would not grout that. Caulk matched to existing grout would be my preference.

If you want a line a fixed distance from the floor, just use a thin board of appropriate thickness to slide a marking device along the trim

Agreed. Never grout edges or corners. They only end up cracking and causing more problems

As stated, grout isn’t the solution here. Caulk is the answer.

I assume you're talking about the gap between the base molding and tile.

Usually when base trim is held tight to floor when its installed.

At this point the correct way to finish this would be to add Shoe Molding.

Larsen, botament and mapai all do grout colour matching silicone

Use caulk. And a caulking tool can get you a nice straight line.

Be sure to use a paintable caulk.

And be extra careful to NOT get clear (the label for clear and the label for white look a little too much alike)

This is correct and use masking tape to keep straight lines on both sides while using a tool or card stock to make the caulk look super smooth without lumps or edges.

Don't grout corners. Caulk smoothed over with a tool and that gap will disappear

Thanks for the advice all, I will look for some colour matched silicone!

Thank you!!

Thank you

Do not use grout or caulk. Install a shoe mould to the floor.

Grout will crack. Caulk is going to look dirty and awful after a month.

I’m really glad you’re taking this advice; the floor will flex differently than the walls, as does tile from skirting, so it would just be crack city. A flexible caulk is 100% the way to go. Or a wood corner bead (looks like a long stick with a side profile like 1/4 of a circle); less cleaning, though some caulks do much better with resisting grime than others.

Use quarter round molding. It will bend to the contour of the floor and when standing, it will look perfect.

White caulk or shoe string molding would look great!

100% agree!

Caulking baseboards. https://youtu.be/n9GSeS8YpgA

DAP Alex Plus White Acrylic caulk is your solution here.

https://youtu.be/9riTpAjyfLM

Not silicone! Nothing will stick to it. Not paint or even more silicone if you need to fix it later.

Disagree. Looks dated and like you're hiding a mistake. And one more crevasse that'll collect dirt over time

This is what toenail trim is for

What would you recommend?

I'm on team caulk or team put a teeensy bit of wood in there and then caulk. But mostly team caulk. Houses now have much crisper lines, cleaner looks. That's just my observation. I take care of rich people, so I do stuff like this.

Caulk will eventually crack and split. I’m a handyman for 30 years, I give my customers options, pros and cons and let them decide.

I have the qtr round in my home with hard wood floors. I like the look.

You are 100% correct. 1/4 round molding is the way to go. Less maintenance and looks good.

This is the correct way to do it.

This Alex really let me down on my last project, it has been cracking like hell. Had great luck in the past but wouldn't risk it again

Here's my wip on a very similar set up, with both shoe and caulk. I would skip the caulk and just use shoe next time

And if you watch a couple of videos on caulking it will give you some tips on how to get it straight and even. The back of an old toothbrush handle works very well if you want to tool it after your line.

Same here. Worked great 3-4 years ago, but tried it again last month and it was awful. Consistency was all over the place and cracked like crazy once dry. Maybe they changed something in the formula recently?

This should be the top answer. For one, that gap is too wide for caulk—you won’t be happy with the result no matter how careful you are. Shoe molding is the way, and it’s flexible enough to ride the small ups and downs of the floor. If you want a super smooth look you can do a thin bead of caulk on the top on the shoe molding where it meets the floor trim, but NOT between the shoe molding and the floor because the wall/trim will expand/contract differently than the floor. Good luck!

Hats off. I do hear that

GE Silicone II is flexible and can be used anywhere there's going to be moisture or movement.

My favorite is Polyseamseal. Done deal.

Yeah, that's what quarter round and shoe moldings are for.

That's baseboard not skirting, and you should be caulking not grouting.

Taping & caulking a straight line is kind of a skill learned by experience. I can do it after years of practice, but I'm not sure how to tell you how to do it.

An alternative is, you could match the caulk color to the trim (white) and tape the floor.

Fair warning on white caulk: most of it isn't intended to hold up as a finished surface. It tends to yellow with age (and maybe uv exposure?) So if you want it to look best you should paint it. This does of course depend on the product you use. The more silicone a caulk has the harder it is to get paint to stick to it. And there may be some white caulk that doesn't yellow. I can't tell you one though!

As a post lower down says a "shoe molding" aka quarter round is the right product for this job.

You just made me realize why we use silicone mats in baking

As others have said, anytime you transition from vertical to horizontal you want flexibility, not rigidity. Houses move a substantial amount, and different planes need to be allowed to without cracking.

There is such a thing called sanded caulking that you can find to match the color of the grout. And since its silicone you won't have cracking issues.

Bingo.

Edit: yes, caulk is what you want. I saw the black lines and it looked like a big gap, but it’s clearly drawn on now that I zoom in.

Agreed that silicone is the way to go for areas with moisture, but they can be more of a pain to clean up since they're not water soluble. Acrylic caulks can be cleaned up with water before they're dry so it's a bit more forgiving if you're not a caulking pro.

In theory, both should be good for areas with movement but I've heard silicone holds up a bit better over time.

Change of plane, grab that caulk and make it rain

Shoe molding is what you need.