wood rafters exposed to fire and heat
wood rafters exposed to fire and heat
(OP)
Hi all,
I am looking at a conventionally framed roof that has experienced a fire. I have identified the rafters, ceiling joists, and collar ties that are clearly damaged by charring. They are fairly localized.
I notice that nearly all the rafters are darkened by soot and smoke along the ridge. Also I notice that the rafters are shiny where they have been weeping sap.
I would appreciate any armchair opinions or references to literature that discusses this condition. I would not necessarily think that the strength of the rafters have been compromised by the weeping sap but it is indicative of exposure to heat and I recall discussions in other threads about the effect of heat on the strength and durability of wood.
In this particular case, the roof is rather simple and modest in size and I think that replacement with trusses might be most practical. I'm not inclined to nickle and dime the entire roof with a piece by piece evaluation. This case is in Alberta, Canada. The lumber is not stamped but is most likely DF or SPF.
Thanks again.
cab
I am looking at a conventionally framed roof that has experienced a fire. I have identified the rafters, ceiling joists, and collar ties that are clearly damaged by charring. They are fairly localized.
I notice that nearly all the rafters are darkened by soot and smoke along the ridge. Also I notice that the rafters are shiny where they have been weeping sap.
I would appreciate any armchair opinions or references to literature that discusses this condition. I would not necessarily think that the strength of the rafters have been compromised by the weeping sap but it is indicative of exposure to heat and I recall discussions in other threads about the effect of heat on the strength and durability of wood.
In this particular case, the roof is rather simple and modest in size and I think that replacement with trusses might be most practical. I'm not inclined to nickle and dime the entire roof with a piece by piece evaluation. This case is in Alberta, Canada. The lumber is not stamped but is most likely DF or SPF.
Thanks again.
cab





RE: wood rafters exposed to fire and heat
Here's a link...
Fire Damage
RE: wood rafters exposed to fire and heat
ahh...grass hoppa thank yoo
RE: wood rafters exposed to fire and heat
Ron: Hear about the wooden cow?
Wooden milk!
Dik
RE: wood rafters exposed to fire and heat
Now I have to try to eat again.
Mike McCann
MMC Engineering
RE: wood rafters exposed to fire and heat
RE: wood rafters exposed to fire and heat
Sorry Mike... I just remembered it... goes back 40 years... Have another bowl of fruitloops...
Dik
RE: wood rafters exposed to fire and heat
EIT
RE: wood rafters exposed to fire and heat
Dik
RE: wood rafters exposed to fire and heat
thread337-304619: Does heat damage wood?
RE: wood rafters exposed to fire and heat
...and dik, I'm way late on drafting our fire damage FAQ/Whitepaper. Been working on a book (not about fire damage...just construction), but will have the edits done for that in a couple of months. I'll try to be a bit more diligent.
RE: wood rafters exposed to fire and heat
Dik
RE: wood rafters exposed to fire and heat
I'm just taking over the authorship from another author who retired. I did some editing on the last 2 or 3 editions, so the publisher asked me to take it over for the next (9th) edition. Beats having to do it from scratch!!
Yes...you and JAE will get a copy. It's heavy enough that it will hold down paper on a windy day, so at least you can get some use out of it!
RE: wood rafters exposed to fire and heat
Dik
RE: wood rafters exposed to fire and heat
No Charring generally ok
Any charring needs replacements
Charring at bearing ends - questionable?
EIT
RE: wood rafters exposed to fire and heat
Dik