Thread: Hairy Floor Joists

I've seen this a time or two in the really old homes, but never had a clue as to what it is. I'm hoping someone here can enlighten me. These are photos of a wooden floor joist in the basement of a 108 yr. old 4 family flat in St. Louis city. Typical of most of these old homes, this one has a stone foundation that moisture comes through, and they are chronically damp. This seems to be a growth of some sort, but it appears to grow very slowly. I don't think it's a mold, but of course it I could be wrong. It does not seem to deteriorate the joists.

Thanks a lot for your help in identifying this ..... stuff!

In simple terms it is mold or fungus, your choice of terminology....

Did you probe the wood? My SWAG is that the wood is going to be fairly soft.

Originally Posted by Kevin Wood

Not that this is wrong Scott, but in the majority of training we have been taught to say mould or mold like substance.

Why say that?

What is a Mold/Mould like substance?

Why not call it what it is?

I review more reports where home inspectors try to soften the blow of their findings by using phrase like that. The problem with reporting like that is the client many times does not understand it is a problem, it then escalates after they take ownership and this is when the attorney gets involved.

I don't know what it is either (probably a fungi) but it is typical on very old lumber in damp locations. I usually see it under porches of 100 yr old houses. While it looks funky I have never found it to be a structural issue as there is always rock solid wood beneath it when probed. If anything, the fuzz is probably protecting the wood beneath. It's probably old growth wood reacting to damp oxidation with protective hair where newer lumber just rots.

It is a wood decay fungus. Mold does not eat wood. That wood is worthless.

'Fungus' is certainly more accurate than 'mold'. What Mark said.

Fungi as a rule are aggressive feeders, so if they are not eating the wood, they are drawing food from somewhere, dirt or mud on the wood maybe. Likely, there are roots in the wood sucking moisture from the wood cels, and the part we see is only the fruiting bodies. Eventually, the wood fibres fall apart.

I would recommend a treatment with a fungicide. Something that ugly can't be trusted.

Originally Posted by Mike Lamb

I don't know what it is either (probably a fungi) but it is typical on very old lumber in damp locations. I usually see it under porches of 100 yr old houses. While it looks funky I have never found it to be a structural issue as there is always rock solid wood beneath it when probed. If anything, the fuzz is probably protecting the wood beneath. It's probably old growth wood reacting to damp oxidation with protective hair where newer lumber just rots.

Exactly what I've observed, Mike. Lord knows the stuff has had literally decades to work on breaking down the wood, but there is always sound wood underneath this hairy coat. If it is indeed attacking the wood, it must be a very slow growing substance. I'm not convinced that it's actually attacking the wood. It may be like Mistletoe. It likes to hang around what it's growing on, but it's actually eating something else.

Regardless if it has been around for years, it is our job to report what we find that is abnormal, improper or broken. What we are seeing is not normal! This just needs to be reported as abnormal fungal growth on the wood framing and it needs to be taken care of by whoever you want to list in the report. Chances are very good that the wood will have some soft areas. Most likely that is old growth oak or some other hard wood and it can take years of abuse.

It's a fungi growth (wood destroying organism). I include a WDO inspection with all homes I inspect here in WA State. I pack a large 20 inch screw driver in old crawlspaces, it works good for scraping/probing stuff like this. I use the handle as a hammer to knock on wood, helps to determine if wood is structurally sound or deteriorated.

Originally Posted by Scott Patterson

This just needs to be reported as abnormal fungal growth on the wood framing and it needs to be taken care of by whoever you want to list in the report.

What needs to be taken care of is the excessive moisture which in this case is beneath the living space of the home.

I see this type of fur often enough but it's outside beneath old porches. It's not abnormal where I come from and I have never seen it to be a structural defect.

Originally Posted by Mike Lamb

What needs to be taken care of is the excessive moisture which in this case is beneath the living space of the home.

I see this type of fur often enough but it's outside beneath old porches. It's not abnormal where I come from and I have never seen it to be a structural defect.

Different types of wood decay fungus attach wood at different rates. You may not see a concern, but generally when wood decay fungus is present it significantly weakens wood.

I see many old porches and do not generally see WDF on the wood. Generally there is enough ventilation on the one I see.

Wow, that's wild! Great swathes of fuzzy fungus. Looks like there are a few species of fungi there. They are molds, a type of fungus, and they are consuming their normal food: dead organic matter. They need moisture to live, so that has to be addressed before anything else. The fungal infection is so extensive and dense in areas, I'm betting there's rot there somewhere. It's better to be rid of the severely infected wood anyway, as it's full of spores and could have hyphae (in the form of fine root-like structures) deep in the wood. It could be weakened without actually having areas of obviously soft wood.

Mistletoes are parasitic, they live of the tree they inhabit. Other plants, such as many ferns, orchids and bromeliads, get their nutrition from debris rather than from the plants they live on. They are called epiphytes.