- Author
- Winandy, J. E.
- Title
- Effects of Fire Retardant Treatments After 18 Months of Exposure at 150 deg F (66 deg C).
- Coporate
- Forest Products Lab., Madison, WI
- Report
- FPL-RN-0264, March 1995, 15 p.
- Keywords
- fire retardant treatments | exposure | moisture content | temperature effects | plywood | roofs
- Identifiers
- strength effects; chemical effects
- Abstract
- In some situations, fire retardant treated plywood roof sheathing and roof truss lumber have experienced strength loss from thermal degradation. The combination of elevated temperatures on roof systems, fire retardant chemicals, and moisture may prematurely activate the fire retardant. Previous studies examined the physical, mechanical, and chemical properties of fire retardant treated wood at various temperatures over a short period. In this study, we examined the rate of strength loss at elevated temperature over a long duration. Small, clear Southern Pine specimens treated with six different fire retardant chemicals were exposed at 150 deg F (66 deg C)/75 percent relative humidity for up to 18 months. The results, consistent with those of previous studies, clearly show that the phenomenon of fire retardant related thermal degrade is systematic and potentially quantiative. The results also support the hypothesis that the lower the pH of the fire retardant treated wood and/or the dissociation energy of the treatment in the wood, the higher the rate of strength loss over time.