Chapter 4: Types of Gutter protection on the Market Today
Filter Gutter Covers
The entire logic behind filter gutter covers is to place a piece of foam in the actual hollow part of the gutter. This filter prevents (simply by occupying the space) any leaves or other debris from collecting in the trough of the gutter, but is supposed to allow water to flow through.
As you might imagine, these foam filters end up brittle, dry, and can even blow out of the gutter and down the street. After just one summer of baking in the hot sun in a literal oven (your gutters are 3 sided heat reflectors that can and often do reach temperatures of 165 degrees on the surface in direct sunlight) they often resemble old chalky Styrofoam.
The manufacturers claim that the fungicides and other chemicals will keep these foam inserts pliable and problem free for years. The truth is they often times don't last much more than 1 or 2 years and then they need full replacement. Most commonly, their tops get clogged with leaves that need to be brushed or washed off and underneath the filter is usually a black moldy mess.
However, a major consideration is what happens to the capacity of the gutter. Gutters are designed to hold a certain volume of water. If you had a sponge that takes up to 1/3 to 1/2 of the volume of the gutter, what is going to happen in a heavy rain? The water is going to cascade over the gutter and you might as well not have gutters in that case.
Bottom Line: These are a short term solution and will limit the capacity of your gutters to handle a heavy load.
