This document describes the intervention techniques for repairing rendering mortar in building facades. It applies to those whose binders are limes and cements. Especial emphasis is made in the enumeration and description of each of the repair techniques, although each case requires a specific study to address the problem. The mortars to be considered are produced "in situ", industrial or semi-industrial. A normative annex is included for the listed buildings of cultural interest or qualified, deserving special consideration.