Abstract Long-term performance of historic buildings can be affected by many environmental factors, some of which become more apparent as the competence of the fabric deteriorates. Many tall historic buildings suffer from water ingress when exposed to driving rain conditions, particularly church towers in the SW of England. It is important to recognize that leakage can occur not only through flaws in the roof of a building but also through significant thicknesses of solid masonry. Identification of the most appropriate intervention requires an understanding of the way in which water might enter the structure and the assessment of potential repair options. While the full work schedule used an integrated assessment involving laboratory, field and archival work to assess the repairs that might be undertaken on these solid wall structures, this paper focuses on the laboratory work carried out to inform the writing of a Technical Advice Note on the effects of wind-driven rain and moisture movement in historic structures. The laboratory work showed that grouting and rendering were effective at reducing water penetration without retarding drying rates, and that use of internal plastering also had a very beneficial effect.