I had a similar problem albiet with a much smaller project ... A "big board". My husband wanted to over engineer it to death. I finally told him firmly but gently that I knew what I wanted, would appreciate his assistance, but not if it was at the cost of not getting the product that I wanted - because after all I had the expertise in this particular area, he didnt know which end of the iron got hot!
Hubby and I go through this a lot, I usually let him win, but there were times that his expertise in engineering was not as well suited to my expertise in the given area ( mostly dogs, my whelping box was a disaster!). This time I really put my foot down though.
Do listen to him, and do thank him for his input, but if one of his ideas is wrong - you have to say thanks but no thanks.
Have fun with the new room.