This work presents a model and tools with which stakeholders and others involved in the conservation and maintenance process to make informed, evidence-based decisions for the treatment of painted steel-sheet roofs on historical buildings. The aim is to bridge the communication gap between research and practice and to provide useful tools for balancing technical, economic, environmental and historical values. The presented research is based on research and field experiences from practice in Sweden, and focuses on the different stages of building conservation: anamnesis, diagnosis, therapy and control/monitoring. The results are exemplified by systematic descriptions of material characteristics, anticorrosive treatment procedures and quality control checkpoints. A material and method matrix is proposed that can be used in diagnosis, planning and documentation of general procedures, or which can be refined for specific object procedures. It could be used for comparing cases, for suggesting areas of further work or for setting minimum levels for documentation. The matrix can be connected to different quality standards of conservation. It may favour the communication and systematic assessment of working procedures for different substrates, and the further development of best practices.