Why is the stain not the place to repair?
Because water runs along the decking and rafters before it drips, and the stain marks where it finally came through the ceiling, not where it entered the roof.
A leak can enter at one point and travel along a rafter for a long distance before it shows. The stain on the ceiling marks the end of the route. Repairing the roof at the stain alone will leave the real opening untouched, and the leak will return at the next storm.
The attic is therefore the first place to look. The wet wood, the dark staining and the damp insulation show the route, and the highest point of that route is the likely entry.
How is a leak tested before it is repaired?
Water is run around the suspect joint from a safe position, and the attic is watched for the first sign of water. The test finds the gap without waiting for a storm.
A test shows whether the joint is the entry. Water is poured around the flashing or along the shingle line, and the attic or the ceiling below is watched. If water appears within the time of the test, the joint is confirmed. If not, the search continues.
The test is done carefully, from a safe position, and it is recorded in the note. A repair that is confirmed by a test is more reliable than one based on a guess.
What is the difference between a flashing and a shingle leak?
A flashing leak runs from a joint at a penetration or a wall, while a shingle leak runs through a line of failed shingles. The two need different repairs.
A flashing leak is usually at a fixed point: a chimney, a vent, a skylight or a wall junction. The water runs from the joint along the decking, and the repair renews the flashing and its sealant. A shingle leak runs through a line of failed shingles, often along an eave or a valley, and the repair reseals or replaces those shingles.
Sometimes both are present. A failed flashing lets water in, and a lifted shingle line lets it run further. The roofer checks both, so the repair does not leave one of them open.
What should a homeowner do while the leak is found?
Put a bucket under the drip, move valuables away from the wet area and photograph the stain. Those steps protect the house and help the diagnosis.
Place a bucket and a towel under the drip, and move rugs and furniture from the wet area. Photograph the stain, and note the date and the weather that caused the leak. The photographs help the roofer and are useful for any insurance question.
Do not climb onto the roof when it is wet or icy. The roofer will check the roof from a safe position.
- Put a bucket under the drip and protect the floor
- Move valuables and rugs away from the wet area
- Photograph the stain, the room and the date
- Do not climb onto a wet or icy roof
How does a leak differ between a storm and a thaw?
A storm leak shows wind-driven water, often at the windward side and the flashing. A thaw leak shows water backing up at the eave or a valley, and the cause is ice rather than the joint.
A leak that appears during a storm, with wind-driven rain, usually points to a flashing joint or a lifted shingle on the windward side. The water is pushed up under the covering and runs down the deck. A thaw leak appears a day or two after the snow has melted, usually at the eave or a valley, where water has backed up behind ice.
The timing and the place of the leak give the roofer the first clue. The diagnosis then tests the joint that the timing points to, rather than checking the whole roof at random.
