Folks,
The floor joists in this 1930’s home has a black substance all over. It isn’t fire damage/soot, but appears to have been applied just to the joists. I think it’s some kind of water-proofing, maybe a bitumen or tar substance, but I’d like you know for sure. PLEASE help out on this one–and if you know the name of the stuff, that would be helpful. Thanks a million!! Picture is attached!!!
Philip T. Jones
Jones Property Inspections
Sure wish I could touch, smell and feel.
What does it look like to me from the picture…
I’m thinking creosote you used to be able to buy in a can and brush on. Drips on the bricks are actually a good thing as it shows its thin enough to drip. I suspect whoever applied it was thinking it would help protect against rot or insects.
Ditto!
I was going to mention creosote but felt it was more brown in color. So I didn’t, but I did say etc. Does that count. 
Isn’t creosote sold today more of a green color? You know the new and improved stuff that they sell out of the local Depot’s.
Creosote is my guess. We see a lot of it down here from 1940’s pier & beam homes. Here it is usually just applied on the main beams and not on the floor joist. You can usually smell it as well when you enter the crawl.
Looks like an accellerant applied to the flooring system. :mrgreen:
Creosote. I see it from time to time in my area. Scrape it with a knife, and the tell-tale smell will be more evident. I generally find it applied to the flooring system in crawls and basements that have been damp or wet for many, many, many years.
Could be one of these two Products:
Creosote, patented in 1831, was the first wood preservative to successfully protect wood from ground contact and high moisture. It is distilled from coal tar (a by-product of making coke from bituminous coal) and is toxic to fungi and most other decay and wood-boring organisms. Because it is oil-based, it stays mostly in the wood, rather than leaching out. By the 1920s it had become the treatment of choice for railroad ties. Unfortunately, creosote is smelly, ugly, unpaintable, and toxic to some plants. Furthermore, it is now classed as a known carcinogen.
Pentachlorophenol (penta), developed in the 1930s, is another preservative equally out of favor. It was the first synthesized pesticide and was widely used until the 1980s. Like creosote, it is an oil-based preservative. The state of California now recognizes it as a carcinogen, and studies show that it becomes concentrated in organisms on the food chain such as fish and birds of prey. Since 1986, use of both creosote and penta has been restricted to certified applicators only.
Pentachlorophenol
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Pentachlorophenol (PCP) is a synthetic substance that was first produced in the 1930s. It is marketed under the trade names, Santophen, Pentachlorol, Chlorophen, Chlon, Dowicide 7, Pentacon, Penwar, Sinituho and Penta among others. It can be found in two forms: PCP itself or as the sodium salt of PCP, which dissolves easily in water. In the past, it has been used as a herbicide, insecticide, fungicide, algaecide, disinfectant and as an ingredient in antifouling paint. Some applications were in agricultural seeds (for nonfood uses), leather, masonry, wood, cooling tower water, rope and paper mill system.
Since the early 1980s, the purchase and use of PCP in the U.S has not been available to the general public. Nowadays most of the PCP used in the U.S is restricted to the treatment of utility poles and railroads ties.
There are two general methods for preserving wood. The pressure process method involves placing wood in a pressure-treating vessel where it is immersed in PCP and then subjected to applied pressure. In the non-pressure process method, PCP is applied by spraying, brushing, dipping, and soaking. Utility companies save millions of dollars in replacement poles, because the life of these poles increases from approximately 7 years for an untreated pole to about 35 years for a preservative-treated pole.
Synthesis.
PCP can be produced by the chlorination of phenol in the presence of catalyst (anhydrous aluminum or ferric chloride) and a temperature of up to approximately 191 C. However this process is incomplete. As a result, commercial grade PCP is between 84% and 90% pure. During the process several contaminants including other polychlorinated phenols, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans are produced too, which can be more toxic than the PCP itself.
Hope this helps.
Marcel 
I agree looks like creosote or tar. one other thing I noticed in your photo . Is there any ventalation?
Creosote. I said it last. Do I get points for that?
Its unanimous. Creosote. Down here there are piles of railroad ties along side the tracks and they are black from the treatment. The town I was raised in had a Creosote plant and at times the smell was horrendous. Couldn’t wait to leave.
I remember painting some this on foundation lumber for a guy in the middle
70’s. He had us mix it with kerosene and oil…
I’m surprised the toxic fumes did not kill all us that day. :shock:
Me too Doug. I grew up in Beaumont, TX just south of where John is located. The local creosote plant that treated railroad ties and telephone poles could really stink up the place. Add in a paper mill a few miles away and it made for some interesting summer evenings. Oh, and I agree, the photo looks like creosote to me too.
Coating retaining wall cribbing timbers comes to mind also when I was working with my old man. Brings back old memories, and I think it was the smell.
Marcel 
Michael,
Yep. Them hot, humid nights there would be a fog with a stench that would get into your nostrils, clothing and hair. And we didn’t have air conditioning in those days, least not in our house, and you had to lay there and smell that crap and sweat. Then one of them damned roaches the size of poodle would dance across your body…oh yeah…good memories.
I remember those days. Laying in a soaking wet bed trying to go to sleep during the heat of summer. Being in school with no ac wasn’t much fun either.
When I was a little kid, we lived in Lufkin, Texas. I still get sick every time I smell the stuff, and I believe I got some dain bramage from the ever-present fumes.