What to Do:
Try locating the leak from inside
1. Perhaps the most obvious start is to try looking for a roof leak directly above the leak in an exterior wall or ceiling. Get adequate lighting or a flashlight. Inspect the attic floor while it’s raining over the leak. Try spotting water stains, water buildup, mold, and wet insulation.
2. Examine the underside of the roof for wet areas or mold near areas of penetration, such as chimneys, plumbing vents, or where different roof planes intersect, valleys, and near dormers. These examples indicate holes in the flashing or bad installation.
3. A leak away from these areas usually indicates problems in the roofing material. Always keep in mind that water can travel sideways before passing through a joint in the roof sheathing, and can travel in a horizontal joint before falling to the ceiling or floor.
4. It’s usually very helpful to record measurements from inside that you can use to locate points of reference from the outside. Measure down from a ridge and horizontally from the center of a sidewall or valley. Or measure distances from other points of penetration or chimneys.
5. If roof rafters are attached to your ceiling, all you can do from inside is take the measurements that’ll help in locating the leak externally and attempt to control the damage internally.
Damage Control
1. Water can travel along the underside of sheathing and down roof rafters before dropping off in one or more areas. To control where you want it to fall, attach a piece of string to the stream of water and route it to a bucket. Water will usually tend to run along the string into the bucket.
2. You can also drill a hole in your ceiling to allow the water to run through it. This technique will keep the water from spreading to other areas, causing more damage. It doesn’t allow the ceiling to become further saturated. It will reduce the chance of your ceiling collapsing and will allow you to use the string to bucket method to collect the water.
Locate the Leak Outside
1. Using some of the measurements you got from inside, scope out your observations using a ladder and/or a pair of binoculars to make it easier on you. Refrain from walking on roofs that are wet or during rain. Especially wood roofs, as they will be incredibly slick.
2. Look for leaves and other debris that could be blocking water flow. It can happen in valleys adjacent to, above any roof penetration, or dormers. If snow is on the roof, a possible ice dam could have formed at the lower edge of the roof, causing water to back up under overlapping layers of roofing material. Remove any debris or obstruction if you can safely get to it.
3. If you’re able to get close enough, examine metal flashings for corrosion or joints that connect to a chimney or other roof penetration. You can patch these metal flashings temporarily. Replacing them is the only permanent solution to it, though. Usually, with dried-out rubber gaskets on the plumbing vents, you can easily replace them.
4. Pay close attention to any areas covered with the black flashing cement. That indicates previously repaired leaks. Try spotting any pinholes or cracks that often occur as the material ages. You can make temporary repairs to them with some flashing cement using a drywall or putty knife.
5. When and if you’re able to try inspecting attachments like antennas, a satellite dish, or anything else that might have been nailed or screwed into the roof. A small flashing that is in good condition should always cover each fastener. Ideally, the best thing to do is not fasten anything onto your roof in the first place.
6. If you determined while inside that your leak was midroof, not relating to any flashing, look for shingles that are missing or damaged. On wood roofs, look for any shingles or shakes that are badly warped, cupped, or cracked. Look for any joints in one course that fall less than 11/2 inches to the right or left side of a joint in the course below. Flat or nearly flat roofs usually require very close inspection to find any deteriorating, worn-out, or damaged areas.