Curious lines

[Michael Bronner]

Anyone want to try and figure out what caused these lines down the sides of the floor joists. The strange dirty lines run down each floor joist from the above joints in the diagonal subfloor. Almost looks like water caused. House sits pretty high and cannot imagine it was from a flood as there is no other evidence.

30024

[Raymond Wand]

Water from wet mopping, floor washing, foot traffic resulting in dust/water stain lines. Nothing of concern.

[Jim Robinson]

Could have been rain way back when the house was under construction.

[Gunnar Alquist]

Zombies are constantly dropping debris and body parts that get between the floorboards. Keep your eyes peeled.

[Scott Patterson]

My SWAG would be what Ray said. From cleaning the floor with various stuff over a period of time. Looks like a build-up of chemicals, soap, mineral salts, etc. in some areas.

[Mark Reinmiller]

Anyone want to try and figure out what caused these lines down the sides of the floor joists. The strange dirty lines run down each floor joist from the above joints in the diagonal subfloor. Almost looks like water caused. House sits pretty high and cannot imagine it was from a flood as there is no other evidence.

30024

I have seen similar staining in similar age houses. I don't know the cause, but often thought that it could be from cleaning up after plastering.

[Jeff Zehnder]

What is the finish flooring above?

[Michael Bronner]

For those who did not ask and the one who did, floors above the photo of the stains were oak. This staining was everywhere, even where there was vinyl or tile. Not fully convinced it was from moping the wood floors with water. Would have had to been a lot of water for many years and the wood floors looked OK from atop.

[Raymond Wand]

Was this plank flooring with gaps or tongue and groove?

[John Kogel]

Have they ever had a fire in the attic?
If not, the subfloors were rained on before the roof went up. What Jim said. But that usually leaves a dark streak, not white. So a hard washing after the plaster work, yeah that must be it. I'll pick Mark's answer. ;)

[Raymond Wand]

Those stains on the underside of planking are from a liquid you can see the staining pattern. Dust/dirt alone would not create stains with that type of pattern.

[Harry Janssen]

Could have been rain way back when the house was under construction.I would agree,it was caused by rain,I have seen people build the basement and put on the floor, then live in the basement,cover with tarps guess what,leaks occurred,hence the marks.
They are to consistant to be caused by mopping the floor or poor house keeping.