Should normally be no problem in a new home as the framing is beefed up for the extra load. (Firebricks weigh from 3.5-7.5 lbs. each depending on whether you're getting 2.5" thick bricks or 1.25" splits.) However, double check by inspecting or checking with the builder. The detail may not be on the plans.

Ok. I actually would need them sliced in half, so not full width hopefully the thin bricks would not crack because of their new thickness.

I hope half bricks don't crack! That's what we used for our floor level hearth!

I actually would need them sliced in half, so not full width

No they come from the factory in "splits"; they're the same width and length but half the thickness.

Good luck with your decision.
I'd like to make a request.... you've had plenty of questions over the last months and I've never noticed that you've gone back on any of your threads and let others know what your decision was or what resolution was come up with from your subs/GC.
Much of the helpful nature of GW is when folks who may be in a similar situation as yourself (with buckling floors, plaster medallions, brick problems etc) and then they can see what someone else has come up with and how it worked for them.
I first found GW about 6 years ago when I was searching for help with a botched tile job.
To that end, if you'd come back to this thread and some of your others and let folks know what you decided and whether it worked to your satisfaction, I'm sure that it would be appreciated by searchers in the future.
I'd also love to see some photos of your home on the monthly "how's your build progressing" thread. It seems that all we ever hear about are the dilemmas and I'm sure there's much positive to share and show. :)

Gbsim, I've avoided posting pictures of our house because I didn't want others to think I was showing it off. Yes, there is much that is beautiful. I will post photos on the update thread tonight.

We have not resolved the wood floor or tile shower problems yet , but I will update when we do.

Oh, good! I've been wondering what happened with the kitchen layout...looking forward to seeing your pictures :)

lavender, the kitchen cabinets are in production--i'm so excited. as soon as they are installed i'll post some kitchen photos. for now, the kitchen is a plain box :)

We had a firebox where we did the same thing (we didn't like the color of the first layer of brick) and we had no issues. It should work.

It can seem like posting photos is showing off, but I think that it is perceived that way mainly in instances where people have never posted with inquiries at all, and then suddenly post a finished kitchen. Some people find that off putting. But I don't think anyone views regular posters as showing off when they share. Most of us are here to get ideas from the community, and I'd hope that no one feels inhibited about posting any project.

The small step will help contain ashes.

Leave it alone.

We have an ash box there for the ashes.

Once you put a screen in front of the fireplace, you will not see the difference in height.

"We have an ash box there for the ashes."
Ash boxes are not for ashes. I just cleaned out an ash pit that had 60 years of depris in it. I removed 5 contractor bags of ash, incinerated cans, toys, original ash box cover, nails, and a leather shoe sole. Most folks forget/neglect to clear them regularly. Residual ash supports mold and odor. Do yourself a favor, clean your firebox and leave the ash pit empty.

What is the ash box for then?
Of course we intend to clean it regularly. I'd never leave it full as you described.