Insulating under an exposed porch
my porch is a four season porch with many windows. The underside is exposed to a walk space outside, making the floor very cold. There is no insulation at all separating the cold air to the floor. Is it OK just to add thick insulation or do I need to also cover the bottom of the porch with plywood?
Would it be better to add the insulation, then add a layer of plastic sheeting, like a vapor barrier. Would all this make the floor and porch much warmer? the porch has a nice gas fireplace also so I want to make the best use of it in the winter.