Roof repair may be a simple task, the biggest part is finding where the repair needs to happen. The source of leaks are tricky to find because of the unique molecular properties of water. Water droplets have great adhesion (molecules sticking to molecules) and cohesion or surface tension (drops sticking together as drops.) Because of this, water spontaneously moves upwards against gravity in small thin tubes, porous materials, or two thin layers very close together. The thinner the area, the higher the water can rise. This is called capillary action.
Capillary action happens when a roof isn’t well insulated or ventilated, it snows, and ice dams can form. The layer of snow melts from the underside, and flows down the surface of the roof, stopping at the snow or ice frozen in the gutters. The water pooling behind this can be sucked up under the shingles, and through small cracks, tears, or nail holes. From there, the water may follow a nail down inside, till it builds up enough to drop down to the insulation. Many drops form a tiny river or pond that seeks the lowest place, looking for a way down into the house, where the brownish stain reveals the presence of a roof leak.
Albert Einstein’s first paper written in 1900 was on the topic of capillary action, but it doesn’t take a physicist to follow the trail back to the leak’s source, just patience and knowledge. When you know what causes leaks, you spot them when you’re driving the streets. Other causes could be torn, missing, or worn shingles, missing or damaged flashing, or caulking around roof vents and skylights, and missing, porous mortar in chimneys. Roof repair done properly makes sure that the minor slings and arrows of outrageous weather won’t devastate your whole roof.