Not sure what this is.


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Old 08-23-18, 05:08 AM
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Not sure what this is.

Hello, I found this white material on some of the rafters in my attic and am wondering if it is mold. It is powdery and some of it comes off when touched. It is on a handful of wood beams in the attic.

Thanks!


http://imgur.com/GF4ZScb
 
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Old 08-23-18, 07:38 AM
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Wow, that picture is so bad it's almost like watercolor artwork. Can you post a more clear photo?
 
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Old 08-23-18, 07:44 AM
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I also had trouble discerning the pic, maybe one from further back would be better ??
btw - welcome to the forums!
 
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Old 08-23-18, 07:55 AM
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It's likely a powdery mildew. You can wear an n-95 mask or respirator and vacuum it off with a shop vac... they make hepa fliters you can use in the shop vac. Then spray it with hydrogen peroxide, vacuum again, spray it again vacuum again if needed then wipe it down with clean cloths. If the hydrogen peroxide foams, then there is still some organic material present.

It likely indicates high humidity due to poor ventilation, so you might want to look into whether or not your ventilation is adequate. Often attics get frosty in the winter and since heat rises the frost near the ridge often melts, soaking the rafters during warm days in winter months. The mold will generally go dormant once conditions are no longer favorable for its growth.
 
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Old 08-23-18, 03:51 PM
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Thank you for the replies, I took another picture below. Hopefully it will be easier to see. I have lived in the house for roughly 4 years and this is the first I am noticing anything. I am not sure if there has always been ventilation issues or not.

Larger view: http://imgur.com/kQLYk1K
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Last edited by PJmax; 08-23-18 at 04:09 PM. Reason: added pic from link
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Old 08-24-18, 03:07 AM
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much better pic
I'd clean it up like X suggested.
We can see the gable vent [that's the ventilation exit] You likely also have soffit vents [intake] Sometimes they get blocked by insulation. There should be baffles installed to prevent that.
 
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Old 08-24-18, 03:27 AM
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I had originally concluded that it was some form of mold . . . . but your better picture shows that the same material is being deposited on the metal bracket as well as the wood; so it's not mold growing on the wood.

It's some form of airborne mineral deposit being carried by moisture in the ventilated air,

Does your vent stack for the sewer system exit all the way through the roof ?

Do you have a bathroom ceiling fan that is supposed to exit through the roof; but only makes it into the attic crawl space ?

If so, that might be white dehydrated "soap" or shampoo from bathroom showers being deposited on the rafters AND metal brackets when it should be going outside.
 
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Old 08-24-18, 04:56 AM
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I thought the same thing as Vermont. It's only on the metal hanger and the one piece of wood. It's some type of reaction with the metal and the wood or treatment on the wood.
 
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Old 08-24-18, 05:14 AM
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Yes, it's interesting that it is not on the roof sheeting. I don't often see mold stop with a definite straight line.

Do you have that white stuff on other trusses or wood in the attic?
 
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Old 08-24-18, 05:18 AM
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And it seems to have adhered to that visible nail which is protruding through the sheathing.
 
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Old 08-24-18, 05:19 AM
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Could it be that a particular piece of wood with a specific sap content or treatment react with the galvanized steel hanger?
 
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Old 08-24-18, 05:23 AM
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If the wood is solid and the "mold" is not growing or migrating I would just leave it alone. I would like to experiment a bit. using a wire brush or what X suggested I would clean half of the wood and hanger and then see if it grows back again.
 
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Old 08-24-18, 05:40 AM
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The way everything else around it is clean makes me wonder if the truss got wet concrete slopped on it while it was still laying down on the ground in the construction phase.

If it seems hard and crusty I'd say it's concrete. Is this the only spot like that in the attic? What's the other side look like?
 
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Old 08-24-18, 05:57 AM
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It looks like mud, as if a pre-fab truss was laying on the ground.

Is the interior of the house sheet rock?
Because it could also be sheetrock dust from construction.
 
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Old 08-24-18, 06:03 AM
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It looks like mud, as if a pre-fab truss was laying on the ground.
My first thought when it was originally posted but the OP said it was white.
 
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Old 08-24-18, 07:50 AM
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It is on a few other pieces of wood in the attic, but doesn't appear to have a specific pattern. The house has soffit vents that go around on two sides of the house and three of those gable vents. When changing some of the soffit boards last year we're not blocked but I can look again. I will also look at the bathroom vents as well to make sure it is not venting I to the space. Thank you all for your i sight so far. I am wondering if this has been happening for sometime and I have just noticed. We have been in the house for 4 years and haven't done any major construxtion. Part of the house that used to be a garage was converted into a bedroom in 2005 and I was told the roof was replaced a few years after that.
 
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Old 08-24-18, 07:56 AM
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Originally Posted by Norm201
Originally Posted by Hal
It looks like mud, as if a pre-fab truss was laying on the ground.
My first thought when it was originally posted but the OP said it was white.
Lots of ways to get white stains at a construction site, sheet rock dust, sheet rock mud, concrete, plaster.
And it wouldn't be the first time the masonry-sub guys "borrow" material from the framing-sub guys...

Guess what "mud" looks like depends on location, within 1 mile of my house, there is white clay, black clay, red clay and even purple clay-

-tangent- back around 2002 Philadelphia hosted the the X-Games which was broacast on ESPN.
The jetski and waterski were held in the Schuylkill Rver at the grandstands where the college rowing usually occurs. The day before, there were torrential thunderstorms upriver in the areas with red and purple soil. Next day was brilliant sun, and the Schuylkill river was bright magenta.

As I walked past the TV uplink truck, I overheard the exasperated local tv crew shouting "NO there is nothing wrong with the color balance on MY camera; I'm telling you again, that IS the color off the water here, yes, the water here IS reddish purple!!
 

Last edited by Hal_S; 08-24-18 at 08:29 AM.
 

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