Thread: What is this?

Really weird. White powder was on the joists but not on the bridging/blocking or subfloor in crawl speace. Not on the cut ends of the joists also.
Saw some spots in the attic also. But not as much. First two pics are from attic area, last is from crawl space. Approximately 1955 construction. Anyone know what this is?

Did you happen to probe at it and see if it was decayed?

Looks like what is known as white rot fungi.

More info from the web:

When White Rot Fungi attacks wood, it breaks down both the lignin and cellulose causing the wood to lose its color and appear whiter than normal. Wood affected by white rot normally does not crack across the grain and will only shrink and collapse when severely degraded. Infested wood will gradually lose its strength and become spongy to the touch. Boards can become severly damaged in 6-12 months, and even faster under moist and hot conditions. White fungus rot most commonly occurs in hardwood materials but can be found in exterior columns, steps, porches, and decks, as well as in doors, windows, and door and window frames. Occassionally, it occurs in wood trim, rafters, joists, sheathing, siding, sills, joists, and subflooring.

This is just a guess,
There is a product that contains boric acid, that is said to prevent termites and other WDI. You spray it on the lumber. It could have been applied befor the floor was down.
Boric Acid natural insecticide, Dry Rot treatment

I think that the third picture shows boards that were used as form boards and then re-used in the floor. Note the one with no "white" on it? This would also account for the very clean sub-floor.

Rick,

Your thinking of the product called Timbor.

The only thing is when it is mixed and sprayed it is a clear material and not white as such and you'd probably never see it used as such in an attic space.

Originally Posted by Rick Hurst

Rick,

Your thinking of the product called Timbor.

The only thing is when it is mixed and sprayed it is a clear material and not white as such and you'd probably never see it used as such in an attic space.

Rick:

Certified applicators in Texas are required to add a dye, commonly "Locate Blue" to Timbor, Bora-Care, et al. prior to application so that application can be verified.

Aaron

Rick H, & Arron
I've heard of those products before, but have not seen photos of them applied.
Thanks for letting me know.

Aaron,

I've never heard of such a requirement. Do you have knowledge of where I could obtain that information?

I do know most of these companies that do the boron based treatments of the sill plates and studs during construction use the dye only for the contractor to know that they have been there. I don't think its an actual requirement by the state though. I just have never heard that it was a requirement at any of the training classes or ever received such notification from the SPCB.

I personally don't do those type of treatments anymore though. The companies that do them are making like minimum wage per their bids, so I will let them have them.

rick

Originally Posted by charles buell

I think that the third picture shows boards that were used as form boards and then re-used in the floor. Note the one with no "white" on it? This would also account for the very clean sub-floor.

I agree with Charles. The white is on specific pieces of lumber, and doesn't appear to be spreading to the floor or adjacent lumber. I think this is dirt or cement, that got on the boards prior to construction.

I inspected a 30 year old home not too long ago that had muddy footprints on the underside of the floorboard. (Had a nice laugh with the buyers.)