Greenhouse floor

[mjmckinney]

I am planning on constructing a greenhouse this spring. The basic structure will be a lean-too placed on the south side of a building. The greenhouse structure will be about 16'x24' or so.

The original plan was to put in a concrete floor with radiant hot water tubes installed in the concrete and heat the floor with hot water. The other option would be a gravel floor and heat the greenhouse with some type of standard hot air heater/furnace.

I really like the idea of heating the floor, concrete will act as a heat sink and there will be no dry hot air introduced from a heater furnace.

Other hobbyists tell me that a gravel floor will be a better option for maintaining humidity in the greenhouse - as opposed to concrete.

For those of you with greenhouses, what kind of floor do you have, are you happy with the choice, and what would you recommend for a new construction?

thanks,

Mike