During framing is not the right time to be making changes like this. @3onthetree just gave you a great explanation as to why. You should be going to your architect with these questions, not to an online forum. I don't know why your builder all of a sudden thinks he's a designer.

Who designed the house and what do they say about the changes?

My first thought was ... act in haste, repent at leisure.

Obviously you must have spent some time coming up with your floor plan, but now your builder wants to suddenly improvise on the layout? What was his reasoning for his proposed changes?

I appreciate the comments!

The main reason for this change is that our living room seems small. After looking into furniture, we measured things out we are concerned about having less than 13ft from the fireplace hearth to the back of the couch. The builder thinks that opening this up could solve that problem, let more light in, and give a better traffic flow to the new side patio area with a better flow for entertaining.

I have sent an email to the architect but we are interested in getting more comments. Thank you.

Make sure the designer of the house is aware of the proposed changes and has opportunity to evaluate any change. Get the proposed furniture layout from the designer that they based their design on.

Well, the first few designs had the Family Room as the larger of the two. When someone converted to CAD, the SunRm magically grew larger and become the primary room by default. You can shift the entire fireplace block into the Sunroom (as it was originally shown) which would flip the room sizes to make the Family 15' deep and SunRm 13' deep. Presumably a masonry FP, the CAD drawn location of the FP will eat into the Master footprint upstairs as well, so shifting the FP fixes that too. Be aware of hearth dimensions.

Also, the Family Room has circulation space on the front window and back blank walls to get to the SunRm. Before, if you wanted you could navigate through Family Room furniture, because the SunRm was more of a "move from talking in the main Family Room to cocktailing in the accessory SunRm" space. Now that you have your main outdoor living patio off to the side of the house through the SunRm, those circulation spaces need to be dedicated moreso for that, which limits the footprint of your Family Room furniture. So, the unintended bonus of having that clear circulation space around the entire perimeter of the Family Room is ---> visually the furniture won't seem as tight.

You wasted all that space on an open foyer with no room for a console, art or bench. I guess you can place a round table in the middle and display flowers and some nick-knacks. It could have been a bit narrower giving more depth to the Family room.

Do you plan on having a TV in the Family room?

How did you plan on using the family room and sun room? Can you still use them in the same way if it now becomes one large room?

You might as well be building a barndominium if you make those changes. That's what the living room/sun room will feel like.

That was the thing that stuck out to me - why is the sunroom larger than the family room?

You have quite a dilemma! I agree that removing the wall between the living room and the sunroom will create an enormous open space, but I also feel the existing family room, at slightly over 13 feet deep, is not spacious even though it's very long and open to the other rooms. Also, I rarely find a room that's partially vaulted is comfortable to be in. I might just extend the family room to @ 15 ft. deep and eliminate the sun room, if that's possible.

I would stick with your original plan, as I like the sunroom as a quieter 'away' space. I suggest making the pantry sink large enough to soak big pots and pans, and add a second dishwasher in there too, particularly if you entertain. I have both in my pantry and get a lot of use out of them, especially since my kitchen dishwasher was a lemon and repairs took weeks!

We decided to move the wall 1.5ft into the sunroom. The architect thought this was a good change. Thank you for the comments as they were helpful!