Flat Roof Meets Wall Leaking After Heavy Snow

The water begins to back up under flashings shingles tar paper etc.

Flat roof meets wall leaking after heavy snow. Looks slightly damp above the door to one side so i guess water is coming down the outside wall past the flashing behind the dot and dab plasterboard and landing on top of the french door. So the chances of roof damage from too much snowpack are minimal after a single snow event. For clarity flat roofs actually have a slight slope to allow rain water to drain off the roof but they seem flat when compared with more traditional steeply sloped roofs. The slope should be a minimum of 1 in 80 but in practice a minimum slope of 1 to 40 should be used to allow for deflection of the roof and for normal building tolerances.

Ice damming can also occur at flashing points so it is also important toclean debris snow and ice from the walls where they hit the roof or terrace because the melting ice or snow will jump the flashing. It could be that a vent is leaking further up on the roof and the water is traveling down a rafter before entering the wall. After heavy rain just not discovered a leak. Water coming down the side of the old french door now doorway to house extension and trickling to the floor.

The homes and structures which are most susceptible to snow damage are those who are uninhabited and or poorly maintained when snow keeps accumulating unchecked over time. When ice or snow fills a gutter any resulting melting water can go over the top of the gutter and back up the roof and penetrate the roofing tiles or shingles. Once water begins to flow into the house it can drip for days. Ice dam leaks plague people in the snow belt.

If a roof only leaks in heavy rain then the above reasons come to mind first and it gives us an easy starting point to successfully track down the cause s of the leak s. During the wintertime roof valleys may collect more snow or ice than the flat slopes of your roof and could cause problems when the snow melts. When the snow piled up on the roof melting occurred and ice dams resulted in water ponding 3 inches deep. Below are two photographs of roof wall step flashing completed and effective of a slate roof against a brick wall below left and in process with step flashing against a dormer sidewall before the dormer siding has been put in place below right.

Proper roof wall abutment flashing examples. Or those which have undergone improper renovations where load bearing walls might. If your roof vent only leaks during heavy rain you may be able to create a shield to prevent the rain from entering the vent. These leaks can happen even if everything on your roof is just fine.

Mold on exterior walls or where roof and wall meet. Metal roofs leak under these circumstances. Some metal building manufacturers will not warranty a roof with a 1 4 inch slope. If a roof leaks whether it has rained heavily or not then there is a good chance that there is an easily identifiable eg broken roof tile or hole in roof cause.