We have existing concrete walls, only gravel on the floor. How do we go about building a wooden floor. We want to install hot water heating underneath the floor. Any help or suggestions appreciated. [Edited by Diane Lorenz on 12-16-00 at 04:39]

For the past 2 days, my wife has noticed a small wet spot on the inside of an outside wall. Curious that it might be coming from the attic, I went up (we have pull-down stairs) to check it out. NOTE: We live in Maryland where temps were in the teens last night. I noticed that ALL the nail tips from the roofing shingles were covered with thick frost, as were the side walls. I didn't want to have the hatch opened for too long, so I took a quick look around, but didn't see anything overtly dripping down the wall where the wet spot was. Is what I've described about the attic frost a normal condition? Can anyone help? Thank you. David