Coal Tar Pitch Roofing
1. General: For an informative, in-depth general article about various roof systems, see this page at the Whole Building Design Guide site, which is maintained by the National Institute of Building Sciences.
3. General: The Pitch Drop Experiment. Check out the decades-long experiment that's still going on at Australia's University of Queensland, intended to demonstrate the fluidity of pitch. You can watch the pitch in real time as it drips once every 13 years or so. This is at room temperature; it gets much hotter on a roof, decreasing viscosity, and producing the "self-healing" quality for which pitch roofs are esteemed.
4. Historic Roofing: For a look at a coal tar pitch roofing guide from 1896, see Barrett's Handbook on Roofing and Waterproofing for Architects, Engineers, and Builders - Barrett Manufacturing Co. - 1896.
5. Safety: For health risks related to coal tar pitch exposure, see this page at the website of the National Center for Biotechnology Information. Safety precautions are important when working with this material.
8. Technical: See this Coal Tar Membrane System Specification, as well as Coal Tar Application and Design Considerations for insight into how a coal tar pitch roof system is put together. Both documents are made available by Durapax.