Blackened attic board...

[Haubeil]

Hey folks, this may be a dumb question or a question recently asked or discussed, if so I truly apologize...but can you tell me what causes OLD attic boards to become black (shown in below photo)!

It looks wet, but it's not...just glossy black.

Thanks in advance,

Haubeil

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[homnspector]

Fire

[Haubeil]

Hmmm.... I never thought about that.

Here's another photo of the same general area...it does look a little crispy!

- Haubeil

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[hausdok]

No,

It's not fire in the first photo. That's tannin that leached out of the original cedar shingle roof that used to be installed over that skip. I see it every day. It's nothing to be concerned with.

The second photo does look almost like the wood's been super-heated but from that angle and with that resolution it's hard to tell.

ONE TEAM - ONE FIGHT!!!

Mike

[homnspector]

Yea, I don't think thats tannin unless it eats away boards. Did you scratch and sniff?

I have never seen staining that was glossy, but maybe.

[Haubeil]

Mike, ...you're GOOD!!!

The roof was once covered with cedar shingles!!!

I'm impressed!

...my client is going to think I'm a smart man!! []

THANKS,

Haubeil

[hausdok]

Hi,

I call it tannin, because I don't know what else would seep out of wood other than tannin and I don't know what else to call it. I see it a lot though and it's always under old ceder roofs. It seems to appear the most on those that are the least ventilated and hottest in summer. There are tons of them around here.

Many years ago it was considered perfectly normal to cut away the perimeter of a shingle roof, lay in a perimeter of 1 by 8's or 1 by 10's and then roof-over with felt and an asphalt cover. Somehow, the perimeter one-bys never got used much but it's very common to find a home here with two or three layers of comp shingles over a cedar shingle deck with those shiny black stains all over the underside of the cedar and the skip.

ONE TEAM - ONE FIGHT!!!

Mike

[Chad Fabry]

Tannin is a surfactant. They're not necessarily tannin stains, but more likely saps liberated from the stained board by the surfactant action of the tannin.

[Jesse]

Not fire, patterns don't make sense. Like was said above, these are stains. Likely from the original roof covering, maybe from moisture.

[swolsen]

I came across a house on Friday that had a similar black staining on the underside of the sheathing and attic walls but only on the north side of the house. At first I thought charring but realized that it was something else. Mine differs a little since there are a few sections where the blackness is flaking off.

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Scott Olsen

[Chad Fabry]

Hi Scott,

Your photos look like a fungus or mold to me.

[Jim Katen]

Originally posted by swolsen

I came across a house on Friday that had a similar black staining on the underside of the sheathing and attic walls but only on the north side of the house. At first I thought charring but realized that it was something else. Mine differs a little since there are a few sections where the blackness is flaking off.

North side = cold side = condensation = fungus.

(Except when it's not.)

- Jim Katen, Orgon

[hausdok]

Hi,

Yeah, I'd also say that's some type of mildew or fungus. If they're nervous about it, a topical application of BoraCare will nuke it. It won't remove the staining, but it should put their mind at ease that it won't spread after that.

OT - OF!!!

M.

[swolsen]

Hey Chad, Jim, Mike,

Yes mold is more what I was thinking. I did scratch and sniff, "no pun intended", but did not detect any musty smell. House is 1940 colonial two story that faces south with a new addition on the north end added 7 years ago. The new addition is also two stories making it a cross gable. The second floor in that area has vaulted ceilings and I see no problem there. I was thinking that when they built the new addition it now blocks the old soffits vents causing a stagnation in that area.

Thanks for the feed back guys

Scott Olsen

[homnspector]

One would think that if there is enough moisture to grow that extensive mold that there would be some other evidence of it, rusted nails, drip stains on the rafters, etc.

[hausdok]

Hi,

That depends on what type of fungi it is. There are literally thousands of species floating around out there and some require almost no moisture to thrive. Some can live off the natrual ambient moisture in wood. Whatever it is though, it looks dead to me. I'd just use the BoraCare to ensure that beyond a doubt.

OT - OF!!!

M.

[Jim Katen]

Originally posted by swolsen

Hey Chad, Jim, Mike,

Yes mold is more what I was thinking. I did scratch and sniff, "no pun intended", but did not detect any musty smell. House is 1940 colonial two story that faces south with a new addition on the north end added 7 years ago. The new addition is also two stories making it a cross gable. The second floor in that area has vaulted ceilings and I see no problem there. I was thinking that when they built the new addition it now blocks the old soffits vents causing a stagnation in that area.

Thanks for the feed back guys

Scott Olsen

I doubt that it's related to the addition. The part of the old roof that's under the new cross gable will have its soffit vents blocked, but it'll also be warm now that the new roof covers it. That area won't experience any condensation because it'll be warm.

You're may be looking at history, not current events.

How old are the roof shingles?

- Jim Katen, Oregon

[Jim Katen]

Originally posted by homnspector

One would think that if there is enough moisture to grow that extensive mold that there would be some other evidence of it, rusted nails, drip stains on the rafters, etc.

If there were enough moisture to cause drip stains on the rafters, I'd expect that they'd have rotted by now. The stuff in the pictures needs very little water -- dampness is more like it.

As for the nails, you have a good point (listening Chad?).

If there's a condensation problem in an attic, I expect the nail tips to be the first things to condense. Perhaps it's a recent roof cover and the galvanized coating has protected them so far.

- Jim Katen, Oregon

[Chad Fabry]

Point driven home; a victory blow for pundits everywhere. 6 penny pun nailed by the master.

[swolsen]

Roof shingle asphalt on both, original house was installed in 1986 and the new addition roof is 7 years. Wood and mold are bone dry, no moisture. Soffits are blocked on the entire north side since the addition is full length of house. There is however moss on the shingles on north side of the original roof only. As for the nails, you can see in the pictures they are not rusted.

Thank you guys for all the input.

[Brandon Chew]

Hi Scott - welcome aboard. I don't have too much to add to what has already been posted. It looks like fungus caused by a combination of too much moisture and too little ventilation in the attic space. You might not be able to determine if it is history or an ongoing problem. I'd recommend they nuke it with BoraCare to make sure it is dead, if I found a moisture source like a bathroom fan that vented into the attic I'd tell them fix it, and if I thought the ventilation in that part of the attic was inadequate I'd tell them to improve it.

Regarding moss on the shingles on the north side of the roof, I've seen that (and lichen) a lot around here and it is not related to what is going on inside the attic space; it is more a function of the particular location on the outside of the home and how much of the day it is in the shade. I think opinion is divided on whether it should be removed or just left alone. Ill-fated attempts to remove it can do more harm than good.

Brandon

[swolsen]

Hello Brandon,

Yes, I agree with you on both the mold and moss. I do not know if the mold is active but will inform them to use the BoraCare to be sure.

Good hearing from you.