Yellow stuff on joists???

[David D. Whitt]

Look at this and give me an idea of what you think this stuff is. Its the first time I have ran across it.
Description: yellow, powdery, light and airy. I can touch it and it blows off like flour. There is evidence of moisture in the space, with efflorescence on the brick as well as rusting tie downs for the insulation.

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[Matt Fellman]

Red flag, Red flag!!!!

Looks like powder from wood beetles..... and a lot of it.

With that insulation there it will be tough to discover the extent of the damage. Even without it there it's often tough since the little critters burrow into the wood.

Whenever you see that look for little exit holes.... they're about the size of a ballpoint pen tip and usually you will find a lot together (but not always). Wood beetles are nasty little bugs.... IMO the worst there is - at least in my neck of the woods.

I'll try to dig up some pictures of damage.

[Matt Fellman]

Here are some from a job a few weeks ago.... damp crawl spaces with no vapor barrier and poor ventilation are the most likley place to find them.

[David D. Whitt]

I did not notice any boring holes, does that ,make a difference?

[Reggie Russell]

Possible mold?

What does mold look like: these Black Mold, White Mold, Green Mold, & Yellow Mold Pictures aid in Mold Detection, Mold Identification, Mold Recognition of basement mold, attic mold, mold in living areas - what does black mold look like in buildings?

[Ken Bates]

I also think it is mold.

Process of elimination (rational deduction logic)

I do recall characterizing a similar yellow (chrome yellow) substance as mold residing in the drip pan of a fan coil unit. Turns out that the QUATS tablet that maintenance placed in the pan was a large yellow pill and the water spread it out to sort of resemble a slime mold. A return visit to this large condo complex provided the answer as I saw it again in another unit and discovered that they use a QUATS antifungal algicide that is a large yellow tablet. They used to use a square dark packet. So ASSumptions can be embarrassing at times.

[Matt Fellman]

I did not notice any boring holes, does that ,make a difference?

The saying says.... "A picture is worth a thousand words" ..... I'd go on to say being there is worth 10,000

It's reallly tough to say from the pics. You quite possibly wouldn't see exit holes with the limited exposure of the floor joists. Another thought I had is that I don't know anything about bugs in your geographical area and it can vary A LOT... so I might be talking of something that doesn't even exist for you.

Here are a couple more pics I dug up of beetle dust in a crawl space where I didn't find any exit holes or damage. I've seen this a couple times in the past. In this case I later confirmed a large amount of wood scraps and debris had been removed from the crawl and there had been no vapor barrier.

Basically, the bugs feasted on the junk on the ground for years and stirred up a bunch of dust which stuck to the floor joists. I spent an hour in a relatively small crawl space probing for damage and looking for exit holes and didin't find a single one. With the past moisture in your crawl space, bugs are a definte concern.

Is it possible to get back in and take a closer look? For the mold stuff mentioned or the bugs I'm talking about.

[Markus Keller]

I'm going to go in a different direction on this one based on how I see the pics. a) that looks like treated lumber
b) if it is treated lumber, then the yellow stuff in the 1st two pics (not so much in the last 2) looks like the powdery discharge? I used to see a lot when I was building porches. As the treated lumber would dry out, some of it would get a yellow/green powder on the surface
If it isn't treated lumber, then I don't know anything. Imagine that
Good luck, Markus

[Bruce Ramsey]

A little bit of googling and I found that powder post beetles never eat softwood, particularly pine. In Alabama the only wood used for building is pine. As such, it is unlikley to be powder post beetles.

powder post beetle - Hutchinson encyclopedia article about powder post beetle

[David D. Whitt]

Markus, Its not treated, but I see what you are looking at. With my luck, it could be another type of mold. The crawl, is moist.....No gutters, efflorescence is present on three sides of the crawl and the tie downs for the insulation has rusted or is rusting. I went ahead and identified it as a moldlike substance and to have it tested. They may clean it for all I know, but I wanted to cover myself.
Matt/Bruce
Thank you for the powder post beetle information. I will be more aware in the future.
Ken/Reggie
Thank you for your input. I didn't know about QUATS either...thanks.

[Matt Fellman]

A little bit of googling and I found that powder post beetles never eat softwood, particularly pine. In Alabama the only wood used for building is pine. As such, it is unlikley to be powder post beetles.

powder post beetle - Hutchinson encyclopedia article about powder post beetle

Wood-destroying Beetles

Anobiid Powder Post Beetles eat hard or softwood.... see my pictures a few posts up. That is pine.... again, I'm not sure about the OP's location but there are definitely beetles out there that eat right through framing lumber.

[H.G. Watson, Sr.]

Looks by color and location, to be decomposing/broken down spray on foam insulation, such as urea/formalin based, or "great stuff" type OR FRT (fire retardancy treatment) leaching exposed to excessive moisture and/or temperature and insufficient ventillation (such as the amonnia/sulfur treatment(s)).

Depending on the "foam" can breakdown as a sandy grit or a fine cornstarch like powder - color & location looks right for a bad unprotected & unseparated DIY insulation/draft blocking project to be same, esp. if the yellow color is more towards the gold tones.

Another thought by location and color/description: Prior Pest control application of insecticide dust, such as for carpenter bees/ants, powder post beetles, or even ZP (rodent pesticide). Consistancy would be more chalk-like or starch-like if the color is more towards the bright yellow school chalk tones (sulfur yellow).

Another possibility might be borate spray residue, a treatment for both WDI and fire retardancy, but the yellow color as pictured looks more like a sulfur/amonia salt for FRT leaching from excessive moisture. Spun fiberglass/mineral wool can hold moisture like a sponge. I don't believe you indicated the area this was observed in - under roof deck/attic, crawl space, etc. Dare I assume this is a crawl space looking at the unfinished /ceiling cavity to the floor above? I didn't see any of the "brick" mentioned - but did see some "block" wall pictured with the noted effluorescense.

[John Kogel]

The colour is too bright to be sawdust from beetles IMO, sorry Matt. Good pics, BTW.

It appears to me to be a mold-like growth. It seems to follow the edges of the insulation, and there's plenty of evidence of moisture there. Also it is on the bottom edge of the blocking, where sawdust would be defying gravity.

Here's another thought. The digital camera can create colors sometimes just by variations in light.

[Tom Roon]

I'd bet $10 to a donut that it's a mold. I've seen this before. The beetle theory really falls apart with common sense. The same powder, uniformly on all the joists? No way. The little critters don't chew like that and it's wood residue they leave, not yellow powder mold. Anyway, the appropriate action is to flag it and recommend someone who "really" knows, can analyze it. JMHO

[Dave Hahn]

Fungi
end of debate
Need to address sources/s of moisture

[John Arnold]

I'm in the mold/fungi camp.

[Brian Johnson]

I too believe it to be mold like substance.
The powder posts beetle theory doesn't match up to me.
I was under the impression that powder posts beetles are the reason we started to kiln dry wood in this country. I always find powder post beetle damage in older 1800's and early 1900's homes with log and tree truck hand hewed beam construction.
As far as I know those beetles are born in the tree and then it is cut down and those beetles go around doing their damage until they exit out of that pin hole we always see.

[H.G. Watson, Sr.]

I'm sticking with FRT lumber, DOT treatment or other treatment residue/salts leaching & moisture issues with the fiberglass batt. with a secondary position of sealant/foam breakdown assuming poorly ventilated moisture ladden crawl or basement view photos.

And yes, powder post beetles can infest and damage SYP and other softwoods (see link from Univ Ky): Powderpost Beetles and Woodworms | Wood Boring Insects old house borers and deathwatch beetles are the most common SYP eaters in the SE esp. infesting damp crawls. DOT treatment on site (twice 24+ hours apart) was common treatment in the SE in the 90s for that purpose. Spot treatment/follow-up treatment with various borate/boron treatments could explain the yellow/chartruse/sulfur-yellow color and pattern, same treatment would deter drywood termites. Age of home?

[bob smit]

PPBeatles don't make that yellow powder smeared-like, on the side of joists pictured. The two however do prefer the same environment, I.e. damp/unventilated. I don't know much about molds, but have personal experience with the exit holes and smeared yellow mold existing together. And yes, if U bang on the joist, yellow type frass will exit these holes yet not the same material that is smeared across the joists.
Two separate entities.
Bob Smit, County EI

[David Bell]

See the same stuff on my pressure treated deck joists.

[John Kogel]

I was under the impression that powder posts beetles are the reason we started to kiln dry wood in this country. I always find powder post beetle damage in older 1800's and early 1900's homes with log and tree truck hand hewed beam construction.
As far as I know those beetles are born in the tree and then it is cut down and those beetles go around doing their damage until they exit out of that pin hole we always see.

That could be how they are introduced but they will spread from joist to joist. Take another look at Matt's pictures. That is powder post beetle damage in milled Douglas Fir. It could be a 1940's or 50's house with a wet crawlspace. East Coast, maybe different.

[Matt Fellman]

That could be how they are introduced but they will spread from joist to joist. Take another look at Matt's pictures. That is powder post beetle damage in milled Douglas Fir. It could be a 1940's or 50's house with a wet crawlspace. East Coast, maybe different.

1961 to be exact... and yep, it was a really damp crawl. This was actually one of the more significant amounts of damage I've seen on such a new house. Most infestations are in 1920's - 40s but it's really more of a construction technology matter (as far as I know the beetles can't tell time )

[Jack Feldmann]

I see this stuff all the time in my area. Its a mold/fungus growth, has nothing to do with beetles (well, maybe Ringo), or great stuff, or treated lumber or any of the other guesses. Termite guys in my area treat this stuff with a spray treatment. I probably see a hundred houses like this a year.
David, how many crawlspaces have you been in in Alabama and not seen this? I bet if you pushed the insulation up, the wood looked pretty normal. Its because the exposed wood is getting the fungus growth on it. IN extreme cases, you will also see dry rot, and wood shrinkage. We get about 60" of rain a year, so its pretty damp, and its very humid too.

[David D. Whitt]

.
David, how many crawlspaces have you been in in Alabama and not seen this? I bet if you pushed the insulation up, the wood looked pretty normal. Its because the exposed wood is getting the fungus growth on it. IN extreme cases, you will also see dry rot, and wood shrinkage.

Not long. I am getting restarted in a new area and am unfamiliar with the homes. I have seen just this one so far. I pushed up the insulation to look at the rest of the board and it looked like perfect southern yellow pine, along with the plywood subfloor. It looked great. When I pushed the insulation, I was surprised to see undamaged wood.

[Jack Feldmann]

Yep, thats the stuff. I call it out as fungus growth on the joists and hand it off to the termite people. It's very common here in East TN. Some of the treatment has a blue tint, so you can tell when it has been treated, but sometimes they use clear chemicals.

I usually check with my moisture meter and see what kind of readings I get. Sometimes they will be quite high, other times only 18% or so.

[David D. Whitt]

Yep, thats the stuff. I call it out as fungus growth(emphasis added) on the joists and hand it off to the termite people. It's very common here in East TN. Some of the treatment has a blue tint, so you can tell when it has been treated, but sometimes they use clear chemicals.

I usually check with my moisture meter and see what kind of readings I get. Sometimes they will be quite high, other times only 18% or so.

I understand that there are those who use moisture meters and those who do not. I have not gotten one for the fact that I have always looked at it as an intrusive testing tool. Maybe I need to invest in one.!? If I recall, there is another post about how using CO2 testers are going above the visual inspection and that it may lead to other legal ramifications, of which I know not.

As far as the reporting goes. Do you or anyone else call this issue out as a "moldlike" substance, or could using "fungus growth" be an acceptable alternative? It seems that there are times where "fungus growth" would be a less threatening way of wording the report, but "moldlike" like would make someone sit up and take notice.

[Jack Feldmann]

I think that a moisture meter is the second most important tool a home inspector should have. Flashlight being number one.
Not sure how else you can tell someone if a stain is wet or not, or find moisture where you suspect it, but can't see it.

To me fungus and mold are the same thing. I call it out as "fungus growth" and defer it to a pest control expert for treatment.

[Tim Allison]

Gotta test to make sure.

[David Nelson]

I can say with utmost certainty that this is not powderpost beetles.

[Steve Howell]

Also not anobiid beetles, termites, nor decay fungi.
However, This and they all thrive in still moist air.
Correct the adverse environment. Treat the wood with a dot preservative, if it will make you feel better.