If your ceiling is water stained, it's a safe bet you have either a roof leak or a condensation problem. It's important to figure out what type of stain you have before you repair your ceiling.
Fortunately, these stains are easy to identify. The condensation stain is usually found on a ceiling panel near an exterior wall, often in a corner. Instead of one large stain, you'll see several smaller circles of stains. These stains vary in size and shape, but they tend to have white centers. Condensation stains appear even if there has not been a rainstorm.

The rain leak stain can be found anywhere on your ceiling: near an exterior wall, surrounding a ceiling fixture, around a ventilation pipe or even in the center of the ceiling. This stain tends to be concentric rings that get progressively lighter as they move outward. The center stain is dark, because it is the oldest stain. Each "ring" by the way, is a separate occurrence. If you see lots of rings surrounding the dark stain in the middle, you know the roof leak has been around for quite some time.

Rain Leak Recommendations

Don't bother replacing the stained ceiling panel(s) until you have stopped the roof leak. To do that, you first must locate the leak. If you're lucky, the leak will be a small roof hole right above the ceiling stain. Unfortunately, roof leaks are rarely that easy to find. It's possible the hole in the roof is not even close to the stain in the ceiling. It's also possible the hole is a tiny space between the flashing and the roof.

To find the roof leak, you must check the entire roof very carefully. Remember to walk on the rafters or a sheet of plywood so you don't damage the seams. Be sure to inspect:
?The J-rail or gutter system.
?The flashing around vents, pipes and roof windows.
?The seams and seals.
?Any loose shingles.
?Any rusted or worn-looking areas.
?Any rumble buttons. (If you don't have rumble buttons, don't add any!)

Also perform inspection from the exterior of the roof. You will also find it help full to do an evening or nighttime inspection. While one person is in the attic, and another on the exterior of the roof - the antic inspector can shine a bright drop or flashlight in these common areas or near where the leak is staining. The person on the exterior will then be able to see the light shine through the area that is allowing the water to enter.

No water source above your leak area? Check your vents starting with the highest, usually your furnace and hot water tank vent. Dryer or bathroom vents are also possible sources of water. Water will follow the vent pipe on the inside until it comes to a low joint where it will exit the pipe and drip on whatever is underneath. The first thing to do is to climb on the roof and make sure the cap has no rust holes, and that the flashing around the pipe is sealed. You can also seal the pipe joints with tape if they are accessible. There are several styles of vent caps out there on the market, and you may have to change out the cap for one with a better hood on it.

Condensation Recommendations

Do you have brown spots on your ceilings? This could be caused by condensation. Condensation means you have too much moisture building up in your home. Because the stains are on the ceiling panel, the first place you should check is the area above the ceiling panel.
Remove a panel to see if there is a vapour barrier. The vapour barrier could be a plastic sheet, or it could be attached directly to the insulation. The vapour barrier is important because it keeps the moisture away from the insulation.
If you don't have a vapour barrier, you will need to:

1. Install a vapor barrier above your ceiling panels, or
2. Paint your ceiling panels with an insulating primer that will also act as a vapor barrier.

The second method is considerably easier than the first, but it is not as effective. If you intend to add insulation above your ceiling or to replace your ceiling panels, make sure you install a vapour barrier at that time.

Other ways to reduce condensation build-up:

? Install roof vents to increase air circulation in the roof cavity system.
? Keep inside air circulating with fans. You can also run the furnace fan.
? Reduce moisture build-up in the kitchen and bath by using the exhaust fans.
? Use a portable dehumidifier in the room where you have the condensation stains. To prevent problems, buy a dehumidifier that will shut off when the collector pan is full.
? Avoid venting your clothes dryer under your house or in your house.
? Check to make sure nothing is blocking the cold or warm-air registers.
? Install interior storm windows to keep condensation from forming on windows.
? Check the base of your house to make sure the skirting is well ventilated, the ground is covered with either rolled roofing felt or plastic sheeting, and the blackboard is intact.

If you have no success in finding your leak then it is time to call for help. Check your yellow pages and contact a qualified roofer. Verify his expertise in identifying and repairing roof leaks and get a quote before committing yourself.