Links to hi-res images. Please credit WWPI:
https://fireretardantwood.org/wp-content/uploads/Steiner_tunnel_test.webp
Proposed caption: A Steiner tunnel device used to conduct fire tests such as ASTM E2768. In this test protocol, a test sample is exposed to continuous flame for a 30-minute duration. To achieve the result required for structural fire-retardant wood, the flame must not progress beyond 10.5 feet at any point during the test.
https://fireretardantwood.org/wp-content/uploads/2018-10-03-14.36.05.jpg
Proposed caption: Type III construction, such as the multi-story apartment complex shown here, is the largest market for structural fire-retardant-treated wood (FRTW). Because of the buildings for which the codes specify use of fire-retardant-treated wood (FRTW) often are intended to have high occupancies, codes require structural FRTW to undergo performance testing, including ASTM E2768, that is much more rigorous than is required for non-structural wood applications such as interior finishes.
https://fireretardantwood.org/wp-content/uploads/Commercial_canopy.jpg
Proposed caption: In addition to Type III construction, fire-retardant treated wood is required in other structure types that have a greater than normal fire risk, including canopies at shopping malls and fuel stations, for example.
The Test Report Summary: https://fireretardantwood.org/wp-content/uploads/FRTW-Testing-Report.pdf
FireSpec: — Fire-Retardant-Treated Wood: what it is and what it isn’t: https://fireretardantwood.org/wp-content/uploads/FS_What_FRTW_is_1225.pdf