We had a direct-vent fireplace installed on an interior wall in a newly constructed home. The fireplace leaks a lot of cold air at the bottom -- we've caulked around the soapstone face and taped where the gas line comes in. LSS, the chase is not enclosed -- it is open to the air space above this sun room area in our house, and merely has insulation (in the ceiling above) laying on top with the vent pipe passing through the insulation. The builder is trying to rectify this situation for us, but I'm not sure that he knows what he is doing. I've read about proper construction of a chase for direct-vent fireplace, but am wondering what the thoughts are in the Hearth Room. Many thanks.