I have a house built in 1950 with cinder block and plaster construction. Because the plaster is laid against 1x4's which are masonry nailed directly to the cinder block, I have no room for insulation. Can anyone suggest a way to increase the R value of my walls other than pulling down the plaster and studding out the wall? I have hot water baseboard along the base of the walls, so studding out would force me to relocate that as well as losing floor space. Is there a insulated drywall product on the market that I could lay directly over the plaster?