I am finishing a attached room in a house I bought, exterior is finished. Inside 2.5 walls are exposed 2x4s which requires R19 in MA. Thought closed cell foam was the answer but didn't like the 1800 dollar price for about 200 square ft of surface to fill (considering 3 large window and door). Is this price high? My options as I understand it are 1) add 2x3s to all the 2x4s and use R19 fiberglass, 2) use R13 in 2x4s then cover all surfaces with R7 foam board. Then I guess I sheet rock over the foam board? I like to keep the extension from the 2x4s as small as possible due to the windows in place, which is why I originally thought closed cell foam spray.