Help requested on attic sheathing pics

[Gregory A. Liebig]

I inspected a home today that had a condition that I haven't seen before. At first it looked like it might be fire/heat damage but it extended too far along (5 rafter spans) the sheathing. The galvanize duct shown in the pictures is a spacer between a can light and the insulation. This black started at the north wall of the home and extended about 5 feet to the south.

[jbreazeale]

Greg...I see you're on line...this is an older home, isn't it?

[jbreazeale]

From the pictures it does look like heat damage. Also, I'm guessing the roof covering is relatively new. Was this home recently remodeled? Do you have a picture that shows the whole area? It will be interesting to see what others say, but from what I see my bet right now is on heat damage, and there has been some remodeling/repair as a result.

[Gregory A. Liebig]

The home was built in 1955. There was a new roof installed last July. My thought, also, was possible heat damage. The unusual thing is there is no evidence on the bottom any of the rafters.

[jbreazeale]

You wouldn't necessarily see damage on the bottom of the rafters, if the fire wasn't very extensive. At any rate, it doesn't look like the structural integrity has been compromised. As long as I was certain about the quality of any remodeling, I would probably call it out as an FYI item. If not, I would refer it to a structural engineer. BTW...isn't all that emanating from the soffit vents? As if the damage had an external cause....

[Gregory A. Liebig]

[quote=jbreazeale BTW...isn't all that emanating from the soffit vents? As if the damage had an external cause....[/quote]

That is an interesting thought.

I wasn't concerned about any structural damage. There wasn't any significant charring. That's why it was so unusual. It's almost as if there was paper attached to the decking and that somehow caught on fire.

If it was in a vicinity that showed moisture problems, I would almost think it might be more of a "mold-mildew" issue than a heat related one especially since it is only on the north side of the home.

[wforsyth]

I was thinking it was a moisture issue. But it looked like some charring remnant on the insulation below.

[rmacinnes]

I agree with Wendy and I would say moisture problem. Does anyone have pictures on what it looks like when there is an ice dam on roof from inside of attic with poor ventilation.

[klott]

Originally Posted by gliebig

The home was built in 1955. There was a new roof installed last July. My thought, also, was possible heat damage. The unusual thing is there is no evidence on the bottom any of the rafters.

It looks like heat damage to me, in this photo, it looks like the sheathing is newer, there may have been a fire and they replaced the rafters and only part of the sheathing that was burnt ths worst. Go to the local fire department and check their records. If there was a fire, it will be on record. It could have been a low intensity fire.

[jbreazeale]

Moisture will indeed cause that black color, but on solid plank decking like that, I would expect it to show denser along the cracks between boards, and also a bit deeper into the board. You can see in the pics where the new roofing nails come through, and the wood is "clean". At any rate, if you're confident that there's no damage to the structural studs, I don't see much more than an FYI note in your report.

[wforsyth]

I hadn't opened the first pic for some reason, and looking at that one I think it does look more like a light fire or something similar.

[Donald R. Peterson]

I see no charring, but a paper thin black substance indicative of an organic growth. The recessed lighting duct/can typically leak gobs "technical term" of warm moist air because of the penetration of the vapor barrier.

[Larry D. Kage]

Originally Posted by dpeterson

I see no charring, but a paper thin black substance indicative of an organic growth. The recessed lighting duct/can typically leak gobs "technical term" of warm moist air because of the penetration of the vapor barrier.

Yes, good read, it looks like organic growth to me also.

[mthomas2]

There has been re-roofing since the event that damaged the sheeting, and the exposed wood splintered outwards at the nails has not darkened, so unless the roofing is very recent the process that darkened the wood has not continued. It also looks like it's *possible* (hard to be sure) that that there may have been localized repair (shingle replacement) at the area above the darkening. Was there evidence of such repair visible at this location from the exterior?

[Gregory A. Liebig]

Originally Posted by dpeterson

I see no charring, but a paper thin black substance indicative of an organic growth. The recessed lighting duct/can typically leak gobs "technical term" of warm moist air because of the penetration of the vapor barrier.

This could explain why the "discoloration" stopped so abruptly. IMO, even a low level fire would leave some evidence on the adjacent deck boards. It could also explain the rafter issue (no significant marks)