We are building a screen porch on the rear of our bungalow in the NC mountains. It will really be more of living area because we will have a masonry fireplace to extend it's seasonal use. There will be deep overhangs surrounding the porch (at least 30 inches) and two sides will be "house." The porch will sit fairly low to grade, probably around 18 inches and therein lies the problem. We were going to do either a polished concrete or a tile flooring but a friend of mine has recently built a house close to where we are building and he has had problems with his polished concrete. Where we live it is not uncommon to have extreme variations in temperature daily. Just this week within one 24 hour period the temp changed 60 degrees. My friend is a science teacher and he attempted to explain the problem to me. It had something to do with condensation and the concrete sweating. He advised me to avoid using a concrete foundation for my porch. However since I'm building so close to grade, what are my options? Keeping in mind there will be a wood burning fireplace out there, what would be both safe, practical and attractive?