glupson-I was prepared to spend another $50,000 if the room was 25’ X 20’ X 14’, the site of my extra land adjacent to my family room. However, on 3-17-2017 the City of Los Angeles passed a anti-mansionization law that downsized to 20% buildable area on 20,000’+ lots (25% on lesser size lots) zoned RA. Since 1/4 of L.A. is a zoned RA, that killed construction/additions beyond the reasonable size for large lots. However, they kept in place 50% buildable area for under 7,500’ lots and 45% over on R1 lots, the majority of lots in L.A. So this stupid law allows 4,500’ mansions on 10,000’ lots to still be constructed overshadowing neighbors with modest 1,200’ homes which is very much still happening. So, I used two of my four slightly oversized garages to build an interior of 15.8" X 19’8" X 10’ high listening room with those 16" thick exterior walls..