I am considering insulating my basement. Just wondering if anyone has any other ideas or input on payback. Here are the details: basement is 1536 square feet with radiant heat in the slab. I currently keep the basement temp at 62 degrees. One 28 foot section is stick framed and the rest is 8" concrete wall aprox. 8 feet tall. I was thinking I will put up 2" styrofoam T&G;panels held in place with 1" x 3" strapping. I figured it will cost around $450 to $500 bucks. What are your opinions on sealing the walls first? They were sealed with the black tar from the outside before it was backfilled and my basement has always been dry. Thanks for the input.