Technical Advice Note I is part of an occasional series of notes on practical and technical issues which arise in the care and conservation of historic buildings and monuments in Scotland. They provide guidance on the principles involved in a particular issue and are not intended to be used as prescriptive documents or as specifications on site.

Rather than model specifications, the intention has been to provide an introduction to the subject of lime and lime mortars which should assist those involved in the repair of traditional buildings to draw up appropriate working practices for the particular situations with which they will have to deal.

The Note draws together existing information on traditional lime mortars for the benefit of specifiers and practitioners working with traditional masonry built structures in Scotland. The principles and techniques described are relevant to brick as well as stone structures. The Note describes and discusses the principles which underlie the use of lime mortars and aims to provide a sound basis for their specification and use.

Although the basic principles of using lime mortars are similar for all trades the main emphasis of this Technical Advice Note is on repointing and masonry consolidation. Advice on the conservation of plaster-work is contained in Technical Advice Note 2 Conservation of Plasterwork. Harlng, rendering and limewash will be covered in future Notes.

The contents include a brief historical summary of the use of lime in building, an outline of the technical issues involved in repairing lime-built structures, and guidance on the selection of materials and on techniques of using lime mortars.

Professional supervision of the type of work described in this document should be undertaken by an architect or surveyor with sound working knowledge of the use of lime and of the principles of building conservation. But nevertheless, no matter how comprehensive the specification, the final quality and success of the work will depend on the ability of the craftsman. Work on site should be undertaken by suitably skilled and experienced craftsmen or women, who can demonstrate an ability to use appropriate techniques and materials.

This Note was drafted by Pat Gibbons of the Scottish Lime Centre Trust for Historic Scotland. In its revised and expanded form it replaces an earlier note on the subject issued in 1988.