Wood Handbook, Chapter 18: Fire Safety of Wood Construction
U.S. Department of Agriculture, Forest Service, Forest Products Laboratory
See Page 11, Last paragraph of left column and top of right column-----some interesting observations about longterm low temperature pyrolysis…I have seen some quoted temps for unpiloted ignition of this wood as low as 350-375*F.
From the WETT manual:
"Field reports have shown that wood exposed to temperatures as low as 120C (250F) will begin to char and may ignite over time. In order to provide a margin of safety, 90C (194F) is considered the maximum allowable temperature to which combustibles (wood) should be exposed for long periods.
The clearances specifications in installation codes like Canadian Standards Association (CSA) B365 (Installation Code for Solid-Fuel-Burning Appliances and Equipment) are based on the distance at which the heat source will cause the temperature of the floor, wall or ceiling to approach 90C (194F)"
Some interesting #'s in these documents.