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Flo-Free, Leaf Defier, GutterFill & Other Open Cell Gutter Inserts

Leaf Defier Open Cell Gutter Insert

Leaf Defier Open Cell Gutter Insert

Eric submitted an e-mail asking for my opinion about open cell gutter inserts. You’ve probably seen them at your local home show, home improvement store, or online. Maybe you have them installed on your home. They are black foam-like inserts that fit inside your gutter. By filling the cavity of your gutter, they prevent leaves and debris from entering the gutters, yet allow water to flow through. There are several brands on the market and they look remarkably similar to one another.

I was going to avoid writing about this style of gutter guard because I believe these products have design flaws that will render them ineffective over time, and I didn’t want to comment on them before I had a chance to test them. However, I’ve recently heard from people who are considering purchasing this style of protection for their homes, from homeowners who purchased and installed them, and from roofing and gutter contractors who have installed them in the past. Thanks to Eric’s questions, it’s time to write about open cell inserts.

I’m going on record to say that I have not tested these products yet, so my observations are based on my industry expertise, viewing the products, comments from dealers who have installed them, and homeowners who installed or had them installed on their homes.

The manufacturers claims that the open cell gutter inserts accept most-to-all water that drains off roofs, is a true statement, I believe — at least when the product is first installed. Since they’re relatively porous and will absorb water as it flows off the roof and down the valleys, they will most certainly work. Leaf Defier, GutterFill and a half-dozen look-a-likes are designed to fit in gutters like a wedge. Shaped like a right triangle (2 sides form a 90º angle, the third side is 45º), the narrow end of the wedge rests at the bottom of the gutter, and the wide end extends across the entire gutter opening, effectively sealing leaves and debris out of the gutters. As water flows off the roof, it lands on top of the porous material and drains through the cells into the gutter. Flo-Free Open Cell Gutter InsertFlo-Free incorporates a different design but the same drainage principle. Flo-Free is 3/4″ thick industrial-strength nylon, according to the manufacturer. One end of the product is designed to sit against the bottom of the gutter and the other end rests the back edge of the gutter, creating an upside down J-effect. Flo-free reminds me of a reusable furnace air filter or the colorful wiry round plastic pot and dish scrubbers, while Leaf Defier and GutterFill look more like the foam padding inserts that protect computers, TVs and audio systems.

The primary contention I have with the open cell gutter inserts is the product design. Most of the inserts look similar to a right triangle. Since the foam-like material is inserted inside the gutter, the area on which the water flows is flat, and it sits below the gutter lip, which will create a barrier that makes it difficult for small debris to wash off the surface. Hopefully, you see where I’m going. In order for a gutter guard to be effective at shedding debris, it needs to have an angle — essentially a downward slope from the back to the front of the gutter. With the exception of Flo-Free, these products have no slope; therefore, no ability to naturally shed the debris that is bound to land on the top surface. This is a significant problem because without a slope, it is likely that debris will not only collect, but will do so quickly. While some debris may blow or wash off the top surface, I suspect more debris than not will stick to the surface. When leaves get wet and dry, they have a tendency to bond together with other leaves and debris, which make it all the more likely that you’ll have to brush off the surface in order to dislodge the debris from the surface. While the manufacturers claim that pine needles will “roll off” the surface to the ground, I don’t buy it. Shingle granules will definitely not roll off the surface. If anything, they’ll lodge in the porous openings. Depending on the size of the cells, some granules may wash into the gutter like the manufacturers claim, but I believe that most will settle within the cells and the inserts will have to be removed from the gutters, cleaned and reinstalled on occasion. Even if these systems continue to allow water to get past the debris into the gutter, the fact that you’ll have to clean off the surface on a regular basis will likely outweigh the perceived benefits of the system. Flo-Free is arced across the gutter opening, so it looks like a dome. The good news is that the forward facing arc will help coax debris off the surface, but the rear-facing arc will cause debris to get stuck between the shingles and the peak of the arc. The only way you will avoid the rear-facing slope is if the shingles cover this area, in which case, Flo-Free may be the most effective of the open cell systems.

Let me tell you about three stories I have recently heard about these systems:

#1 — A homeowner in Seattle called telling me that he purchased open cell gutter inserts because he has a metal roof that limits the type of gutter guards he can install on his house; it was relatively inexpensive compared to professional grade gutter guards, and he could install them himself without special tools.

He said that pine needles build-up on the surface, which requires him to clean the surface, but his biggest complaint is that when the temperature drops below freezing, the water freezes within the cells and his gutters became like an ice tray.

#2 — A roofing company near Knoxville was asked by a customer to install Leaf Defier once they completed a roofing job. Within 2 weeks of the work being completed, the homeowner called the contractor asking them to remove the system because he was dissatisfied with the product’s performance. And the kicker was, since he made the mistake by selecting the product in the first place, he told the company that he would pay to have the gutter inserts removed.

#3 — A remodeling contractor in Chattanooga said that he installed the open cell inserts on his grandfather’s house, and his grandfather hasn’t forgiven him since! In fact, the contractor said that his grandfather used some choice words when he called his grandson telling him to remove gutter inserts from his house.

GutterFill Open Cell Gutter InsertI believe that open cell gutter inserts will keep leaves and most debris out of your gutters. I believe that water will be able to enter into your gutters freely for some period of time, but I believe over time that water flow will become restricted depending on how much debris lodges on top of and inside the inserts. I also believe that these systems have inherent design flaws will make them a higher maintenance solution than what most homeowners are willing to tolerate. While the cost of these systems is less than a typical solid gutter cover or micro-screen system, the cost savings will be offset by the higher upkeep and poorer performance over the life of the product. Considering two of the three homeowners cited in the stories above requested that the products be removed from their homes shortly after they were installed, I believe that it’s safe to say that unless you live in an area with very little debris affecting the performance of your gutters, steer clear of this option.

  • Chuck

    Maybe you should do more research before making a condemnation of a product. Testimonials do not count as research. If you really want to be informed, there is a thesis out there performed by SELCUK FILIZ, a graduate student (at the time this was written in 2003) at North Carolina State University entitled EVALUATING THE POTENTIAL USE OF HIGHLOFT NONWOVEN FABRICS FOR RAIN GUTTER APPLICATIONS. The testing & research methods are described in detail and shows, based on unbiased results, that the original filtration system patented in the 1970’s, is superior over every commercial product out there.

  • http://www.GutterGuardsDirect.com Johnathan


    Thanks for your comments. In fairness to our readers, we should note that according to your Web site, you are the V.P. & National Operations Manager for Gutter Filter America (GFA), which is a marketing company that distributes and helps companies sell GutterFilter, a product similar to what is discussed in our blog. It is also of note that you have sent other favorable comments in the past, which we elected not to publish, since they were redirects to your company’s Web site.

    Let me first say, the article is not a “condemnation” of open cell gutter inserts, and I was clear up-front that I had not yet tested these types of products. Rather, this was an opinion based on comments and observations from consumers who had purchased these products, dealers who had installed them, as well as my years of experience in the business. While I said nothing in the article about “research,” if testimonials from actual installers and consumers don’t count as a form of research about the effectiveness and success of a product in real-world conditions, then what does?

    I read the college thesis, written in 2003, by Selcuk Filiz, then a North Carolina State University graduate student. It’s actually a very interesting paper, so here’s a link to it for any readers who would like to read it: http://www.lib.ncsu.edu/theses/available/etd-08212003-170405/unrestricted/etd.pdf.

    There’s nothing in this thesis that I wouldn’t agree with, and I believe that if you re-read what I wrote, my comments about water-flow through the material are in line with his findings. It’s also important to highlight that he tested only the rate flow of liquid through various densities of “highloft nonwoven fabrics” that could be used for gutter protection applications. His tests were limited to an indoor lab facility, and he states the following in his paper:

    Filiz was comparing some products currently on the market, including Gutter Helmet and Flow Free (sic) (Flo-Free), which is a variation on the type of products he was testing, and one of the products I mentioned in the article. On page 32, Section 2.3.1, he said, “The nylon mesh traps pine needles, shingle material, etc and should be cleaned to avoid blocking of the flow of rain water.”

    On page 101, #6, Filiz says, the “effects of cold weather, mold and mildew, ultraviolet light, pollen, pine needles, etc on the fabrics” have yet to be tested.

    On page 101, #8, Filiz says, “In time, fabrics might loose (sic) their (sic) loft.”

    I guess you were referencing this thesis to prove a point, so let me open this up and provide you with an opportunity to showcase that your products are just as or more effective than others on the market. Let’s not kid ourselves, each product has pro’s and con’s. If you’d like to produce verifiable data or research that refutes my comments about leaves, pine needles, and debris sticking to the top of or lodging within these systems, please email me the info, and I’ll be happy to publish it.

    We would also like to test GutterFilter alongside other open cell insert systems, outside, in real weather conditions over a period of time, so if you’re up for the challenge, get in touch with me, and we’ll put your system to the test.

    Thanks again for your comments, Chuck. I look forward to hearing from you.


  • Rick

    Hi Johnathan. Thanks for your thorough & insightful comments. I’m looking for the most effective leaf guard I can get that I can purchase & install myself (I’m pretty handy) and does not require any disturbance of the tiles on my roof. I wouldn’t mind cleaning out my gutters just once a year for smaller debris, but most guards don’t seem to allow you to do that once they are installed. Any recommendations? Thanks.

  • Johnathan

    Thanks for your question, Rick.

    I believe the most effective gutter guards incorporate a micromesh screen into them. We have tested several with similar results, and you can read the article in this blog by selecting this link. When deciding what style of gutter guard to purchase, there are a number of factors to consider besides price. Chiefly, your decision should be driven by what types of trees you have around your house. If you have pine or fir trees, then you’ll definitely want to go with a micro mesh screen. LeafFilter, which rests solely in the gutter, is available here. Other manufacturer’s, such as Leaf Solution and Gutter Glove may sell direct if they don’t have dealers in your market, so you may want to call them to find out. Both of these products slide under the shingles and secure to the front of the gutter with sheet metal screws. The other promising micromesh product we tested was DiamondBack. Unfortunately, the galvanized metal base rusts when exposed to the elements, so I cannot recommend it.

    If you have deciduous trees that don’t shed too much small debris in the spring, then you might get away with a guard that has small holes, such as Leaf Relief. Leaf Relief, manufactured by Ply Gem Industries, a division of Alcoa, is made of aluminum sections with a series of small drilled holes. The guards sit on top of the spikes or hidden hangers in your gutter and are secured to the gutter’s front edge with 1/2 zip screws. Leaf Relief includes a 10-year pro-rated no-clog warranty and is available at commercial building supply centers (not Home Depot or Lowe’s). Cost wise, it’s probably about one-half of the micro screens, but it may require additional maintenance that the micro screens won’t, and the warranty isn’t as comprehensive. Besides the holes being considerably larger than the micromesh screen, the product sits flat on the gutters and it has a relatively high edge, which helps contain water on the gutter guard surface. While it keeps the water on the guard, the high edge and lack of a forward slope will also keep more of the debris on the guard. The company says a 6 mph wind in dry conditions and 23 mph in wet will remove most of the leaves. It’s available for 5″ & 6″ gutters and a variety of lengths. Leaf Relief is worth a shot, in my opinion, if you don’t want to go with one of the micro mesh screen products.

  • Selcuk Filiz



    You got my thesis very right, I definetely do not condemn open cell gutter structures, which was a nonwoven material in my thesis. There are superior substrates to that of these I used in my study that will definetely perform better than the material I used. I disagree with comparison to a product of 1970s.


  • Erik Klaproth

    In answer to your questions or comments on Flo-Free, which I bought and installed on my own house, as well as two of my client’s houses: In general, it works quite well, with the limitations you mentioned, i.e., the recommended installation process allows the formation of a “shelf” which traps quite a lot of debris. I was cleaning it about once every 3 months.

    Just this past week, though, a snowstorm showed another shortcoming of the product. On a metal roof, the snow slid down, and as it re-froze at night, it “grabbed” the fabric of the flo-free and tore it loose of it’s moorings. This morning I awoke to several pieces of the flo-free hanging merrily from the gutter. In fairness to the manufacturer, it does say in the instructions that “ice cleats must be installed on metal roofs with this product”, but in this case, it would not have made a negligible difference. The manufacturer was very nice about offering me a couple tubes of sealant to re-attach the material, but I declined. I think I’ll try another type. I do have pictures if anyone is interested.

    As snow is very rare here in North Georgia, I am not sure if this would happen again, but I think I’ll go with another variety of guard.

  • http://www.GutterGuardsDirect.com Johnathan

    Erik and I took our conversation offline, and he provided me with the following response:

    Here are a few pics of what a recent snowstorm did to the Flo-Free material I installed about 2 years ago. It was installed to the recommendations of the manufacturer, with the exception of “ice cleats”, which are an uncommon item around North Georgia. In this case, the ice cleats would have made no difference anyway, since the thawing and refreezing of the snow was to blame for the Flo-Free material being pulled out of the gutter. Although it was an uncommon winter storm, it would have happened in any winter storm, making the Flo-Free material an unsuitable choice. I’ll try something else next time. I am a small contractor here in North Georgia, and was recommending this quite highly, but that’s going to change.

    Thanks for acting as a clearing house for info!

    – Erik Klaproth
    Principal, carpentry & more.

    To see photos submitted by Erik, visit our Facebook page (no registration required).