Mortar samples were obtained from a variety of dwellings in the UK with the majority from houses with rising damp. This paper aims to evaluate the mortar attributes and their influence on rising damp. The samples were characterised in the laboratory in terms of pH value and water absorption characteristics and examined using scanning electron microscopy to reveal the microstructure. It was found that the water absorption characteristics varied considerably, with older mortars having a higher sorptivity and higher concentration of soluble salts. The majority of building mortars treated for rising damp in this survey were approximately 100 years old and had a typical pH value of 9. A good understanding of the relationship between rising damp and mortar characteristics was developed, which may be practically employed to assess and mitigate rising damp problems.