Water should NOT stand on a sloped roof!
While performing a one-year warranty inspection at a new home, a home inspector noticed standing water on a sloped roof. It was clear that the roof pitch over this newer patio addition was too shallow for the composition shingles that had been installed above it. And there was really no excuse for such a mistake.
The owner of this particular one-year old home said she had paid a private contractor to build the addition a few months earlier. Unfortunately, she – like most home owners – did not know about the importance of matching the roof covering material to the angle of the roof pitch. Not following a manufacturer’s installation instructions can lead to serious roof leaks, even mold. The home inspector reported the identified defect to the home owner, and advised her to ask the contractor to come back and repair it. He agreed to a phone consultation with the contractor, if it became necessary.
The Roofer Is Supposed to Match the Material to the Roof Pitch
In construction-speak, “roof pitch” is a term used to describe the angle, or slope, of the roof surface. Pitch is usually expressed by a phrase like “5 in 12,” or “5:12,” or sometimes just “5 pitch.” In this example, the phrase means that for every 12″ of horizontal measurement away from the roof edge, the roof surface gets 5″ higher. It’s easy to see that the water shedding ability of a roofing company akron will have a great deal to do with how high the pitch angle is. Saying it another way: “the higher the pitch, the faster the water will run off a roof.”
Let’s say it again: Water SHOULD NOT STAND on a sloped roof!
Manufacturers of composition shingles (the type that is installed on most U.S. homes) have to provide product warranties for their shingles. For that reason, they have a keen interest in those shingles being installed correctly. So these manufacturers print the installation instructions ON EVERY BUNDLE OF SHINGLES. And, in those instructions they recommend that the roof pitch be greater than 4 in 12, so that water will run off properly and efficiently. If a roofer uses composition on a roof with a pitch of less than 4, special preparations must be performed, like doubling up the roofing felt, and using sheet metal flashing at valleys, etc.
Now, here’s where it gets interesting in our particular story. EVERY MANUFACTURER of roof shingles insists that composition shingles NOT BE USED when the roof pitch is less than 2 1/2: 12. In fact, violating that instruction (and a few others) will void the warranty on the entire roof. In other words, composition shingles are not designed or intended to be used with a shallow roof pitch. Wind-driven rain will actually blow water back up under the shingles, under the felt and the wood deck will get wet, and fail to dry properly. Over time, this wet deck will warp and rot, and leak. So, while it might be keeping the interior (i.e., the attic and ceiling) dry early on, it will be slowly losing the fight.