Q. Our home in the Berkshires was originally built as a gardener’s shack and subsequently expanded in every direction. The floorboards in the living room seem to have shrunk over time and now permit cold, damp-smelling air into the house. There’s only a few inches between the floor and the earth so there’s no solution from beneath. I have area rugs over the space now but wonder what, if anything, I can put under them as a moisture barrier. I thought of plastic sheeting but there may be condensation that might damage the lovely old painted planks.