Deforestation in many parts of the developing world has to led to a deterioration in both the quantity and the quality of wood (timber) available for housebuilding, threatening the viability of traditional building techniques. This paper examines the effects of a deteriorating resource base upon traditional house building practices in Mopti (Mali), where the most common traditional house type requires large quantities of strong and durable timber for the construction of the roof. It is shown that the favoured “rônier” wood is no longer accessible to the poorer sections of the population, who have no alternative but to use lower quality wood and less durable species. This in turn means more frequent replacement and maintenance, thus putting greater pressure on the available natural resources, and on household budgets. Those who cannot afford to maintain their houses, live in a state of insecurity due to the fear of collapse from poor construction. The implications for policy are explored, both in Mali and in the wider context. Options include support for the introduction of new building techniques and for the planting of trees which provide good timber for building.