To obtain information on moisture in insulated walls and ceilings which lack vapor barriers, a small exposure unit was instrumented. Indoor relative humidity conditions resulting from normal household activities were simulated in part of the building. The remainder of the interior space was maintained at 35% rh. Walls tested incorporated the usual plaster with oil-base paint, unmodified and with two types of remedial modification (two coats of aluminum paint, exterior 1-in vents). Three depths of insulation were used in the ceiling. The test data showed that insulation added to walls of an older home subject to the climate at Madison, WI may not cause visible moisture problems where mechanical humidification is not used. However, where a rh of 35% is maintained in the house, condensation in the walls is likely without remedial measures. Increasing depth of ceiling insulation resulted in a slight increase of moisture in the insulation, but good ventilation kept moisture at acceptable levels. This information should be useful in regards to renovation of historical buildings.