I had both hot and cold lines open on all fixtures throughout the house. Everything loses all pressure after the lines clear and water stops coming out of everything. But, I can flush these 2 toilets over and over and they refill at presumably normal pressure levels (I don't have a pressure gauge I can attach to the toilet line to test exact numbers, but the tank fills at the same pace as normal). The water in the tank is cold as it fills, as well. If there's no code exception as to why they did this, I have to suspect the plumber somehow pulled a line from the the supply side of the water main. My neighbor (referenced in my first post) got $35k in damages. The toilet tank overflowed bc the float switch broke. My theory I'm going to work to prove is that bypassing the main also bypassed a pressure regulator, which causes the high pressure to break the valve. Our houses were built in 2017, just for reference. Some of his walls have been opened up to remediate the water damage, so I'm going to see if I can go over there and trace lines. Thank you for your suggestions and help!

James, thanks for your reply. We were wondering about the chimney too. It vents the dining room fireplace and the hot water heater. We installed a 90% efficient furnace when we moved in, so that vents out the side wall of the basement, not out the chimney. I'm expecting that the architect will have to incorporate the chimney in the design and we may have to have it built higher to meet code. Yes, that's a gambrel roof on the far side. This house has a nice mishmash of architectural features. No one has ever really touched the original design which makes us cautious and nervous -- the original condition was one of the main attractions to us when we first saw the house. Our architect is an old house owner herself, so that should be a good sign. We are hoping to step the addition in on the left side (looking from the back) by at least a foot. My husband was trying to sketch a possible roof line that would join a smaller hip into the existing hip. His sketch looked pretty good. I was just hoping to see where someone had done something similar. I'm not sure yet what the architect envisions. I guess I need to be patient and let her do her thing. : ) Here's a picture of the side with the gambrel:

Get your financials sorted out first. It will cost far more than you think it will. http://www.remodeling.hw.net/cost-vs-value/2015/ Then, you'll need a plan to present to your city for permits. You can get that from a drafter, architect, or a design /build firm. The first 2 choices allow for cometitive bidding of the project itself, and the third chouce is less hassle to you, but probably slightly more expensive because of the lack of competition.

I have a question. Looking for more wall space to help with the kitchen. If I take the 2nd bedroom, turn it and put it where the foyer is....Then take the bathroom and connect it to bedroom. That should create a wall for the kitchen. Move the laundry to where the bathroom was. Make the master closet smaller. I think that gives me a foyer and hall to the dining room area. Need to look at getting a door from the garage to the inside. But would that work?