Lime plaster is well known for its moisture buffering capabilities but is also susceptible to mould growth. This work focusses on the hygrothermal performance of lime plaster in naturally ventilated residential spaces. Surveys are carried out for 45 traditional buildings of Ahmedabad in India with measurements of ambient variables, such as temperature, relative humidity, wall moisture content, etc. Mould growth patterns of these spaces are related to the measured variables and wall characteristics. Hygrothermal simulations of some spaces are also carried out to observe the moisture buffering of lime plaster. Experimental observations are contrasted with simulation results to see if numerical predictions are realistic.