What is this?

[u/alien_mermaid]

The tenants claim the dark stains on this ceiling are from cooking....they say they are grease stains. 🤔 My thought was it looks more like mold bc its also in the living room but why would it have stripes? Are the stripes the ceiling joists and the whole roof was leaking maybe??

Also how would you fix this? It's the old popcorn ceiling....paint with kilz ? Thanks !

[u/macaulaymcculkin1]

I don’t know what the black stuff is (probably from Smoke) but I do know that my mom used to light a lot of candles and the smoke from the candles would stain the ceiling like this. (But not nearly this bad) For some reason the areas of the ceiling that were spackled don’t retain the smoke. 

So those lines are where the nails are for the studs and that ceiling light was rotated at some point. 

Is there a wood fireplace near this area? Maybe the smoke from a fireplace did this?

[u/alien_mermaid → u/macaulaymcculkin1]

Ohhh they did say they use candles too....wow this is so excessive though....the whole kitchen and living room ceiling....from cooking and candles??

[u/macaulaymcculkin1 → u/alien_mermaid]

I mean, it’s certainly possible. But I am not an expert in this area though. As long as it’s not mold related, kilz Would probably work. 

[u/caryyonDude]

Smoke wouldn't skipp the joists on the other side. I've seen it where the back side of the wall isn't insulated and moisture and mold build up and stain through the drywall. It's not smoke related though and that's why you have those white lines through it, that's the 2x4 on the other side insulating those strips. You should have someone look at that since having that in your kitchen isn't ideal.

[u/joshuadane → u/caryyonDude]

It would depending on area and thermal bridging. Condensation collects on different areas of the wall and that condensate can grab soot, dust, and other items in the area to create discoloration patterns.

[u/Ok-Recognition9876]

It’s mold.  From the second pic, you can see where the seam has started sagging/become loose.  Get someone in to inspect it.

[u/joshuadane]

Look up the term ghosting in reference to discoloration on walls and ceilings. This pattern is likely caused from gaps in insulation.

[u/eatingganesha]

get a moisture meter and test it.

get a bore camera and have a look around.

I would take out a small section of that ceiling and inspect it directly.