What is the black stuff in the first four photos, and the white stuff in the last photo? Is any of it mold, or is it all harmless stuff?

Structure is about 10 years old. Home inspector claimed that the first four photos are just "truss fungus", which he claimed is present in almost all homes. He didn't notice the white stuff in the last photo.

The home inspector claimed that the wood comes like that from the builder's wood supplier, and it is totally normal.

Was the home inspector correct, or was he just making a quick buck on a shoddy inspection?

Black stuff More black stuff Black dots Black dots with material description White stuff

  • The only way to know for sure, is to have it tested. While you're waiting for the results to come back, do some research on "lumberyard mold".
    – Tester101
    Commented Mar 15, 2016 at 23:40
  • Is there excess moisture in this area (poorly run bathroom exhaust duct, dryer vent, etc.)?
    – Tester101
    Commented Mar 15, 2016 at 23:42
  • 1
    If you can't find where the bathrooms exhaust, it might be because they don't have any ducting attached at all. I find all too often, that exhaust fans are installed, but not hooked up to anything. They simply blow the hot moist air into the insulation surrounding them. I'm not sure if it's clueless homeowners, or clueless builders that are doing it.
    – Tester101
    Commented Mar 16, 2016 at 10:26
  • 1
    The best way to find out where the exhaust goes, is to get up in the attic and take a look. For a quick check, simply pull the grill off the exhaust fan, and look through the exhaust port. If you see ducting, you'll have to investigate further. If you see insulation, you know it's done wrong.
    – Tester101
    Commented Mar 16, 2016 at 10:33
  • 1
    If the fans are in the walls, they may also just vent out the side wall of the house - they don't have to go through the ceiling. Commented Mar 16, 2016 at 20:41

3 Answers 3


The mold on the lumber appears to all be on engineered trusses. They were likely stored outside before or after jobsite delivery. It's likely that they were rained on then and developed the mold.

If there's no evidence of moisture problems in the attic now, and the mold doesn't seem to be growing, I wouldn't be concerned. Mold is everywhere already and it's not a health concern when outside the building envelope, in my opinion.

I'd consider misting the floor trusses with a suitable anti-mold solution to prevent spread. If everything stays dry it's probably not an issue either.

The spots on the OSB are just ink splatter from the stamping stage. You can see that it matches the stamp in color and edge bleed. It's very common even in perfectly dry, well-stored units.


Yep, the black is mold baby & the white is drywall residue or "maybe" some water marking, but that is one straight edge. Bleach & scrub-off the mold & increase your attic ventilation to rid the place of mold.

  • I added a little more info to the question. The home inspector claimed that this is what wood often looks like straight from the supplier, and that it is present in almost all homes. Was he full of it? Commented Mar 15, 2016 at 21:15
  • 1
    Yep he's an idiot, & your money-train. You can sue him (actually his insurance co.) for not recommending remediation or at the very least noting it on his report as a danger & a defect.
    – Iggy
    Commented Mar 15, 2016 at 21:19
  • 1
    That's the problem here in america, everybody just wants to sue people. Commented Mar 16, 2016 at 21:54
  • 1
    You've got that right. But, do you know what you said & how precisely correct it was? Only people can sue other people. However, once you decide to sue Police, Gov't, Corporations, Banks, Schools or all of the actual failures, poisons & wrongdoers in society you get nowhere & nothing.
    – Iggy
    Commented Mar 17, 2016 at 0:29
  • I work in a lumber mill and see the fungus all the time. After a board is finished we spray it with a biocide to reduce the fungus growth. If the wood sits outside very long it starts growing. Plywood is really nasty all the veneer sits outside until needed and the sides of the stacks are covered in mold. I think with plywood most organics are killed with the hot press that smashes the veneer and glue together, and cures the glue. but I would get it tested to verify it is not the really bad stuff.
    – Ed Beal
    Commented Mar 17, 2016 at 19:00

Looks like Aspergillus niger, but send a sample to a mycologist at your local university for a positive ID.

  • What's the best way to get a university mycologist to do this? In the past, I have had to spend large sums of money for that kind of work. Commented Mar 15, 2016 at 21:02
  • 1
    No, don't send money. Look online for your local college... follow the links... biology... mycology or the closest relevant department. Call them, ask them if they could connect you with someone in the mycology department. Ask them if they would kindly id a fungus for you, or to refer you to someone that would help. Within a couple phone calls you should be talking to someone that can ID fungi. Ask him about sending a sample. Commented Mar 15, 2016 at 21:19
  • You might try a County Extension Services office when checking to see if the name was more than extension office many states popped up that have these services. Here in Oregon they are free and they have helped me with invasive plants and a non native beetle for free, they came out and eradicated the poisonous plants who knows where they came from. But the Beetle came from a semi truck from Mexico. They told me ~6 months later and the beetles would not survive the winter (they put out a big number of traps). All of this was free to me from some really neat people.
    – Ed Beal
    Commented Mar 17, 2016 at 19:12
  • You cannot identify mold species by sight.
    – J Walters
    Commented Mar 23, 2016 at 1:39
  • The primary way that fungi are identified is by morphology, which is basically a visual description of the structures (sometimes a microscope is necessary). Phenotypical tests are chemical tests- which answer questions like what it can eat or what it is harmful to it- which help to further describe or identify the species or even the strain of mold or bacteria. Genetic tests are rarely done for mold identification due to the cost and, moreover, the simple fact that most fungi can be identified by morphology; and, if in doubt, running a couple of simple phenotypical/chemical tests. Commented Mar 23, 2016 at 12:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.