Is it an old mark or changing damage?
An unchanged stain after a documented repair tells a different story from a mark that keeps spreading. Date your photographs, note changes in shape and colour, and record any softening, bubbling or peeling visible from the room.
Do not press or probe a damaged ceiling to test it. A professional can assess moisture and material condition safely. Fresh decoration can conceal the pattern without resolving the cause.
Why a stain can look dry during a visit
Leaks can be intermittent. A waste connection might only escape during use, or outside water might only enter in certain weather. A dry reading at one time does not rule out every source.
It is worth describing what happened before the visit, including bathroom use, heating changes and rainfall. ADI’s published ceiling investigations include cases where observations and tests were combined to distinguish possible routes.
What the position can tell you
Below a bathroom, think about the fittings, supplies, wastes and seals above. At the top of a building, roofing, loft plumbing and condensation may all be relevant. Around the edge of a room, water can have tracked along a junction or member before showing itself.
The first visible stain is not necessarily the point nearest the leak. Several marks can share one source, and one patch can have more than one contributing cause. Avoid opening up on the basis of appearance alone.
When to repair and redecorate
First establish whether the source is still active and address it. Then assess the ceiling and surrounding area for remaining moisture or damage. Drying and making good may be separate from the leak investigation or repair.
Stain-blocking primer can have a role in redecorating a suitable dry surface, but it is not a treatment for ongoing water ingress. Ask the repair professional what condition the material must reach before decoration. If the mark returns, investigate rather than simply coating it again.