Fungus damage to floor joists

[Frank Bombardiere]

I inspected a home recently that has some white powdery substance that appears to be some type of wood destroying fungus. The wood was almost like styrofoam in these areas and a probe would go right through the joist. The house was only 4 years old and the wood appeared to be fine other than the white powdery substance and the fact that the wood was soft. The crawl space was damp but not more than most. I would like to hear from people with more experience in this type of issue since we have not seen it before. What may be causing this and what needs to be done. There does not seem to be anyone around here that is an expert on this problem and wanted to get some ideas from those that are familiar with it.

[Gunnar Alquist]

I inspected a home recently that has some white powdery substance that appears to be some type of wood destroying fungus. The wood was almost like styrofoam in these areas and a probe would go right through the joist. The house was only 4 years old and the wood appeared to be fine other than the white powdery substance and the fact that the wood was soft. The crawl space was damp but not more than most. I would like to hear from people with more experience in this type of issue since we have not seen it before. What may be causing this and what needs to be done. There does not seem to be anyone around here that is an expert on this problem and wanted to get some ideas from those that are familiar with it.

Hi Frank,

That looks pretty bad there. Yes, it does look like fungus damage. Here in CA home inspectors cannot specify "fungus damage", so we typically get around it by using phrases like "decayed lumber" or "damage probably caused by wood destroying organisms".

In my area, dampness in the foundation crawlspace area accompanied by poor ventilation are the typical culprits with that kind of damage. Increasing ventilation is necessary once the damaged wood has been replaced and any infected lumber treated. Moisture retarders are the typical method of rectifying the ventilation issue if additional vents cannot be installed. Some homes will have mechanical ducted ventilation, but the problem is the systems need to be maintained and homeowners generally don't.

[ROBERT YOUNG]

I am leaning on mold.

Between the floor joists ends, no insulation or vapor barrier. Like part of the cause.
Up to 20% energy loss in basements.

Many types of mold can appear white in color, depending on the type of material on which they are growing, including aspergillus, cladosporium, and penicillium (penicillium is often blue or bluish-green and white). Mildew, a type of fungus similar to mold, may also appear white and powdery.

The columns and shims appear suspect as well.

Soil or concrete flooring? Efflorescence on the CMU?

[Mark Reinmiller]

It is a wood decay fungus. Mold will not damage wood. I have seen similar damage, once in a house about 1 year old. It does take a relatively high moisture level to create that damage. Why it happens only in some houses has to do with whether the wood decay fungus happens to be present. If you look this up you will see that there are different types. Some create white rot and some brown rot. Some very aggressive types have a root-like form.

[Garry Sorrells]

Looks like a type of " Dry Rot" .

[ROBERT YOUNG]

I think we can all agree the soil plate is not insulated and missing a vapour barrier.
You have 33% Moisture Density so conditions are right for fungi growth.
Write up any the crawl space and sole plate deficiencies and the condition of the joists.
Good luck.

- - - Updated - - -


Mold will not damage wood.
Yes I should have mentioned that.
Thanks.

[wayne soper]

Considering the condition of the rim joist, my best guess would be past gutter overflow or patio runoff soaking the rim joist consistently. Dry now would mean the cause may have been repaired but rim joist is ready for replacement.
What Is on the other side.

[ROBERT YOUNG]

Considering the condition of the rim joist,

Morning, Wayne.
I sniped and zoomed in on the lumber at the sill plate.
Now I could be mistaken but it appears to be blocking. If that is the case the rim joist is behind the blocking. Even more reason to hypothesize the rims are in poor condition.
32782



What Is on the other side.

You ask a very valid question.
What's on the other side, Frank?
Is the rim board flashed and clad?
Lot slope?
How high does the foundation project from the soil?
Any images?

[John Kogel]

If the house is only 4 years old, good chance the wood was infected already when they built that floor. The white webs are only the fruiting body of the plant, which has infected the cell structure of the lumber.
There will be nothing but trouble with that place. A fungicide solution can be used to kill what is on the surface, but the fungus will lay dormant in the wood or it will draw moisture from the wood cells until you have dry powder for joists. So IMO. it is too late already to be trying to dry out the crawl.

We see it often in stacks of lumber that even tho kiln dried, were left out in the rain. Lumber that was not kiln dried is more susceptible to that fungus. "Poria" fungus.

[Frank Bombardiere]

If the house is only 4 years old, good chance the wood was infected already when they built that floor. The white webs are only the fruiting body of the plant, which has infected the cell structure of the lumber.
There will be nothing but trouble with that place. A fungicide solution can be used to kill what is on the surface, but the fungus will lay dormant in the wood or it will draw moisture from the wood cells until you have dry powder for joists. So IMO. it is too late already to be trying to dry out the crawl.

We see it often in stacks of lumber that even tho kiln dried, were left out in the rain. Lumber that was not kiln dried is more susceptible to that fungus. "Poria" fungus.

I am with you John, I think they should run from this one. Thanks to all for the replies.

[ROBERT YOUNG]

Likely so. Old infected lumber.

If you know the language of wood, and you do require good hearing, you can hear the good wood talking, "Guy's there's a fungus among-us.":( Almost like , but not completely similar to fungus among-us, would be petrocarbon term-oil. Loses it viscosity too fast. :p

Sorry for the edit. I was so anxious and misspelled loses and Too.
Been waiting over 2 decades to try that one somewhere.

[Gary Burnett]

Frank,
Obviously there is a ventilation issue that is not reducing the moisture under the home as evidenced by your picture of the moisture meter. The home owners probably cover the vents in winter and may have a plumbing leak or just the condensation under the home causes high humidity. I see it in Dallas and since you are in OKC I expect there isn't much difference. Other than repairs to the damaged wood areas, I recommend installing vent fans that operate from a humidistat. I don't recommend vapor barriers around here and don't know of any structural engineers or foundation companies that recommend them either. Seems they capture moisture from condensation or plumbing leaks and just compound the issue. Most people around here don't ever go under their homes to check for leaks. Moisture in the wood needs to be below 20% or fungus/mold is going to grow.
Generally, a structural engineer (or PE) will provide repair requirements along with preventive solutions for this problem.