One of the most common home inspection concerns for home buyers is ceiling stains. While it's not always possible to determine exactly what caused a ceiling stain, the location of the stain will often give away what caused the stain.
Finding The Problem- Moisture Meter
The most obvious concern with ceiling stains is roof leakage. When a home inspector finds a suspicious ceiling stain, they will typically use a moisture meter to help determine whether or not it's an active leak. If a stain is wet, most home inspectors will be able to trace down the source of the moisture and recommend a repair. When a stain is dry, it means the cause of the staining has been corrected or the conditions that caused the staining to occur are no longer present. In these cases, it's a good idea to ask the seller about the history of the staining; specifically, what caused the staining and has the cause of the staining been corrected?
Stains Below Bathroom Exhaust Fans
When a bathroom exhaust fan is connected to an un-insulated duct that runs through the attic space and doesn't make an airtight connection to a proper roof cap, the moisture that's supposed to exhaust to the exterior is going to condense like crazy.
As all of this moisture condenses inside the duct, it eventually drains down to the bottom of the duct and then leaks on the ceiling next to the fan. Boom. Ceiling stain. The fix for this condition is to make sure the duct for the bathroom exhaust fan is properly installed; this means an insulated duct, a short run, and airtight connections.
Random Ceiling Stains, No Roof Leaks
Condensation that occurs in the attic is a common cause of ceiling stains. To help determine if an attic experiences condensation problems, home inspectors should look at the nail heads; if they're rusty and there are stains on the roof sheathing around nail heads, it's a condensation issue. The fix for this is to seal attic air leaks and reduce indoor humidity levels.
Stains Below Plumbing Fixtures Or Radiators
These are both pretty obvious, right? When a home inspector finds a stain below a plumbing fixture, the next step is to use a moisture meter to see if there is active leaking. If the stain is dry, the plumbing fixture above should be thoroughly tested, and then the stain should be checked again.
Stains on the ceilings are definitely worth further investigation, but most of the time they're only indicators of past leaks, many of which occurred a long time ago. Why? Because active leaks will quickly destroy ceilings and they are extremely difficult to hide.