This report, the fifteenth in a series of twenty completed by the Children's Environments Advisory Service for the International Year of the Child, 1979, presents a guide for planning play spaces on roof decks in high density family housing projects where on-grade land is too scarce or too expensive for development as communal recreation space. The technical constraints were evaluated and the play potential of play spaces were examined in case studies of communal roof decks that include play spaces. Technical design alternatives were developed for the provision of safe and stimulating play opportunities for children. (A site visit checklist, a site visit observation form and related correspondence are appended.) (Author/RH)