Water is one of the most common causes of a stain on a ceiling.
Straight line water stain on ceiling.
Yellow stains will likely be painted over with white on the popcorn ceiling.
There can be other sources of water seepage from your roof other than a leak.
The test suggested by one of the responses ie to put a drop of water on the grout and observe it s absorption rate is a good one and to be tested.
A water stain on the ceiling is usually a by product of a roof heating appliance or plumbing leak that seeped through the ceiling and evaporated leaving you with an unsightly patch of dried.
Roof leaks are the main cause of water stains on the ceiling.
To identify a roof leak you should look for the obvious factors like missing or damaged shingles roof tiles torn flashings or loose screws on the exterior of the roof.
Fast forward 4 years and a series of brown stains appeared on the ceiling in that same vicinity.
I knew there was water damage at some point i said to myself.
Some of the stains looked like lines that were dripping down the line from a pile and two looked like singular drops of water the resulted in a stain on the ceiling.
For water stains coming from your roof you ll need to identify the nature of the disrepair.
If the water stain occurs after a period of snow for example this can indicate the formation of an ice dam which requires upgrading your insulation not your roofing.