The Autoclam is an effective and portable non-destructive technique originally developed to measure the permeation properties of concrete as an indicator of durability. It performs three types of tests: water permeability, sorptivity (water absorption) and air permeability, which together provide a reliable assessment of the moisture transport characteristics of porous media. However, the very high permeabilities of some common stone types make it difficult to perform all permeation tests with the existing device. This paper describes several design modifications to the Autoclam that allows its use on high porosity stone. Preliminary results are presented and the use of the Autoclam in building stone research is evaluated.