Within Northern Ireland there is a severe lack of authoritative data on the performance of natural stone (local and imported materials) used on historic buildings, and as climate and pollution patterns are different from the UK, there is no reliable data on which to base decisions for stone replacement and repair specifications. This is further complicated by the fact that many original quarries are now inactive and replacement stone is imported (largely from UK) and matched with local building materials. Consequently, stone conservation decisions are made with little knowledge of likely adjustments (physical, chemical and aesthetic changes) that will occur on exposure to current environmental conditions in Northern Ireland. To help with these decisions we are developing an interactive (web-based) inventory of stone performance ‘in use’ in Northern Ireland related to present and past exposure conditions. The project is a government-funded partnership between university (Queen’s University Belfast) and local industry (Consarc Conservation, a firm of conservation architects). The aim of this joint venture is to facilitate end-users with repair specifications and selection of new and replacement stone fitted to purpose by providing a searchable inventory on existing key stone buildings throughout Northern Ireland. This will include an assessment of performance of the stone types used including structural and chemical durability data and information on visual convergence as new stone adjusts on exposure and existing stone continues to weather.