How wide is the actual firebox? This guide might help, math is necessary. 😊

https://www.hunker.com/12316270/how-to-size-a-fireplace-mantel-to-a-room

Whatever the darker line measurement is would be my advice. Equal distance, of course.

FYI, during our last house remodel, we changed two fireplaces with wall gas keys like yours. The plumber said they could not be extended due to code. I believe the line from there to firebox would have to be completely replaced.

Is it just the way the photo was taken or is the fire box not centered on the wall? Also, I’m not quite understanding the choice of rustic wood and stone against the formal cornice. Aren’t your kitchen cabinet door profiles quite formal, too?

The firebox is centered. We aren't changing the box itself, just took off the old mantel and are putting in the stacked stone and the new one. Here's what it looked like before. Ugly light fixture is going away, recessed light is already gone.

It's hard to say. How high up will the mantel go above the opening? I saw this, but it doesn't feel quite right. (this was from wayfair and the fireplace placement isn't exactly the same as yours.) Maybe it's just me and I'm not used to floating mantels. the picture below feels like it lacks cohesiveness, if that makes sense. Btw I like that your mantel is more rustic than this one.

I didn't even consider height. Now I'll have to figure that out too!

I'll have to measure the opening of the firebox. And then do... shudder.. math...

Jojo's example looks off because it's too high and needs supports to visually connect it to the firebox. You may run into the same issue - hard to tell how high your firebox is Beagles but if you set the mantel too high it will look like it's floating (not in the good way) without some type of bracket to visually connect it.

Also....how tall is your ceiling? Looks like 9' to me but could be 10. That will also influence mantel placement and size.

The ceiling is high. 10 inches. I'm not there until Sunday so I can't measure the firebox until then. As soon as I can, I will do so. I agree about the floating issue but not sure what to do about that. Should I look for a mantel with brackets? Do they offer that?

Where are you getting the mantel? Is it going to be a hunk of wood or a boxed piece? You might be able to have brackets fabricated out of wood wherever you are getting the mantel. Or if you like metal you could look for someone who can fabricate that. Either one can be as simple or as ornate as you want. Our mantel is rustic and outdoors on a porch so I wanted the brackets to be rustic too but the choices are only limited by your imagination. Check pinterest and google. Search mantel brackets and mantel corbels so you get wood and metal options.

Stacked stone and a rustic wood mantle looks good in a rustic or contemporary setting....

But with your traditional builtins and mouldings, I think you'd have a better outcome if you used a traditional mantel and tile. At least think carefully about what is going to happen at the top, where the stone meets the crown.

If it was me, I'd do Ann Sacks tile in a traditional mantel:

Not sure of the height you want for the mantel but the width of Allison’s drawing is just right IMO.

(And you didn’t ask, but here goes: although that style of hewn mantel is lovely will always be in style in appropriately rustic or casual architecture, as a juxtaposition with more formal surroundings it peaked a few years ago. )

I appreciate the comments and suggestions including the opinions on the mantel/stacked stone.

That being said, I have wanted a white stacked stone with a more rustic-y mantel on this fireplace since I first looked at this house last April (the journey to buy it was quite a process). This was my inspiration picture for the stacked stone (not mantel, the mantel is too dark) and it was the first one I saved when we convinced the owners to sell the house to us.

I'm also trying to somewhat temper the formality of the trim and make the house have more of a formal/coastal if that makes sense. Here's what it looks like with my current floors which I think go nicely with the chosen mantel (the built-in unit you see pictured there is being fixed and painted a pastel blue.)

If you can get your stone mason to do this it might be a better support for the slab mantel:

The support is stone and is an integral part of the wall of stacked stone, which gives you a cleaner look than trying to find matching or otherwise appropriate wood supports.

Another idea for a more traditional mantel that still gives you the wood element to echo your floors would be something in scrubbed pine, which would fit with the modern English country kitchen vibe you are creating:

Just throwing these ideas out there. The number of decisions you have to make in the kitchen alone is daunting 😳

Not sure of the height you want for the mantel but the width of Allison’s drawing is just right IMO.

I just drew for width, not height.

Can you send me the link to the first one you posted kswl (or tell me where I can find it if Houzz isn’t pkaying nice with links?) That one could work.

I’m sorry Beagkes, when I try to trace the image back to its source it goes to odd ”buy sites” that are obviously just using the image. Battaglia homes is the builder and they might be able to give you the source of the mantel if you email them the picture.

I will do that, thanks! Of course the one I like is the one that's unavailable :)

Thought this picture might help visually regarding the mantle’s size and location.

Noted you had envisioned the look below (with a light mantle). Just wonder with going for a formal coastal feel, have you considered any other designs. It’s such an important feature; think bigger picture and the effect will have in the room.

On another note, suggest adjusting cabinet’s shelf spacing for more consistency (when wider, accessories normally look better). Adding sconces and complementary hardware would be nice additions as well.

Without seeing a furnished room, it’s hard to suggest a look, but thought these examples might give you pause and just search on line (Pinterest, Houzz, Instagram) for formal coastal fireplaces.

Beagles, mantel beams like the one in Kswl's first photo can be found wherever beams are sold. Usually salvaged. Sometimes hand scraped to look old, when not old. We have previously bought beams, etc from two different lumber yards.