To provide combined moisture and thermal protection for basements, high-density glass fiberboard was used on the exterior of two prototype basements. This insulation-drainage layer can easily be adapted to current construction procedures and the cost is not excessively high. Performance of the 140-kg/m3 (9 lb/ft3) glass fiberboard installed vertically below grade was monitored. Early results are encouraging. Favorable moisture distribution and compressive deformation were found. After two years of burial the insulation still maintained a thermal resistivity that ranged from 22.6 to 26.8 m·°C/W. It is believed that the concept of an insulation-drainage layer has the potential to keep the basement dry, to provide improved thermal insulation, and to enable better curing of concrete. With refined design details the concept is attractive and worthy of continued study and development. This paper describes methods of installation, monitoring instruments, and some findings obtained from two experimental basements monitored since 1976 by the Division of Building Research/National Research Council of Canada.