Do Leaf Guards Have an Effect on Icicles?
Many, many years ago my father-in-law asked me about any detrimental effects of leaf guards on gutters. Being over eighty he had decided that it was time to stop climbing a ladder to clean his gutters. I told him that we had suspicioned that leaf guards would increase the number and size of icicles hanging from the gutters, but that we had no reliable studies to say for sure. So, he became our first test case, aka guinea pig, when he hired someone to add a curved metal leaf cover onto his existing gutters.
During the years that we monitored the effects of the leaf guards we noticed no apparent roof leakage, but my father-in-law did say he noticed that he was having a lot more icicles. I had made similar observations when we pulled into the driveway. But he noticed no other shortcomings and was pleased that his gutters were free of leaves. I even checked a few locations where I thought the guards might not perform as expected, but the gutters were for the most part clear of any significant debris.
One of the engineers at PCI also hired someone to add a curved metal leaf cover onto his existing gutters. He also noticed more icicles in the winter, but he was also pleased with the performance of the leaf guards.
I chose a different route and installed a curved mesh over the gutters along one eave of my garage. I did the installation during a warm day in January over a year ago. I immediately noticed an increase in number and size of icicles over the unheated garage. I also noticed that debris was often trapped where the curved mesh rested on the shingles. Significant debris even got under the mesh which required me to lift the guards and blow the gutters free. After the one full year experiment I removed the mesh and disposed of them, that is, the metal was recycled.
From these in-situ observations I conclude that since leaf guards re-direct and slow the flow of roof runoff off the roof surface, the leaf guards will probably increase the number and size of icicles. The good news is some of these leaf guards will actually keep the gutters clear of debris and none of those monitored contributed to roof leakage over the short term.