A Pattern Language of Natural Homes No.220 Roof Vaults


This is one of a series of articles about A Pattern Language by Christopher Alexander where we illustrate and discuss the patterns using homes and buildings made from natural materials like stone, clay, wood and straw.


Alexander admits that this pattern is the most contentious of them all. A roof carries with it cultural heritage and social expectations which he tries to avoid by a fundamental analysis of the roof while still meeting the requirements of the related patterns such as No.117 the Sheltering Roof.


The criteria he identifies are that the roof:

  • satisfies the psychological sense of safety;

  • provides a lived in space rather than just a hat above the living spaces;

  • give an indication of the social layout of the building; should not be a complicated contrived structure;

  • should avoid bending requiring tensile materials,

  • and should shed rain and snow suitable for its climate.

Taking other patterns in to consideration then collectively these exclude the flat roof, pitched roof and geodesic domes; ironically a popular structure many eco-villages like to play with.

Alexander notes (from 1977 when his book was published) that, "we believe these tension materials [wood, steel] will become more and more rare".


The scarcity of tensioning materials like wood is exactly why the non-profit organisation La Voute Nubienne helps communities in Africa to build the roof vault solution Alexander proposed 35 years earlier. Their work in sub-Saharan Africa is helping to replace the traditional use of timber for roofing. Population growth in the region, together with increasing desertification and regression of forested areas, means that the traditional use of timber is no longer feasible.