Question: I just bought a 1920 kit home in Minneapolis. I want to add a fireplace in the corner of the living room. One wall is outside to wood siding, and one side is an interior wall abutting the bathroom. My thought was to line the walls and the floor with durarock concrete siding, line that with 18 x 3 x 9 inch concrete blocks, and fill that with spray insulation if I can find one that's appropriately heat tolerant, (after reading your site I wonder if durarock itself is enough) and line the inside of that with decorative red brick, or true brick facing (half inch thickness. The Home Depot has gas fireplace burner kits with logs, embers, etc. They sell various lengths of insulated fireplace flues, either 3 inch or 3 inch inside 6 inch insulated galvanized or aluminum tubing. I figure the inside goes out the top and outside, and the outer tube brings air into the back. Then we'd buy a fireplace face with code glass doors, and fashion the appropriate airways. I think I'd buy an electric blower to help suck air through the bottom of the face, and blow hot air out the top of the face. In other words, how little can I get away with and still be safe? Depending on the cost of the walls, I think I can put together a fireplace for $300-$500, which is a lot less than commercial fireplaces Answer: No, No, No....you cannot engineer and build a safe direct vent fireplace without the help of combustion engineers, testing labs and other experts. This will set you back a minimum of $100,000...probably a lot more. This is much more costly than buying a DV fireplace for $900-$1900. It's sort of like trying to build a car....buying instead of building gives you the economy of scale and mass production that has made our modern world so bountiful. Use you DIY skills for installing and finishing your masterpiece.