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Discussion Starter · #1 ·
Hi all! I've installed invisaflow powder coat metal gutter screens around my home in February of 2019. The roof pitch is maybe 4-12 or 5-12. Our basement has a history of water seepage so it's important that the gutters work optimally.

Link: https://www.homedepot.com/p/InvisaFlow-Metal-Lock-In-Gutter-Guard-25-per-Carton-6360-25/205207107

They do a good job of keeping leaves and twigs out. But in heavier rains the runoff tends to overshoot the gutter. I've cleaned the screens and reduced shingle overhang to 1/2". I even tested placing the bottom shingle 1/4" higher than the metal drip edge ("negative" shingle overhang). The overshoot is improved but not eliminated.

Has anyone solved this?
 

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Your problem may be in the photo. I see some holes where water film is staying on. In rain, that film may be strong enough to create a surface for water to drain over, not through the mesh. Maybe the powder coat and wires are too smooth, easier for water to grab the sides. Maybe the gutter is too low. shingles should overhang the drip edge, if undercut, water could follow the drip edge and drain behind the gutter. Eave drip edge should have a built-in overhang.

Try the image aluminum guards. Replace one of these with the guard you have and see if it makes any difference. Look for 6" wide guard that's wide enough to slip under the shingles. Should go under the starter shingles.
 

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Discussion Starter · #4 ·
I agree that the water film enables the water to overrun the screen. I may have made some progress. I experimented with bending a few screens lengthwise to create a gap below the shingle overhang. Once the gap is large enough to cause a waterfall effect, (about 1/2 inch) water drops directly through the screens into the gutter.

It is still TBD which shape will minimize trapping leaves and debris, and a method to make the bends consistent for all the installed screens.

I'll post a photo later.

Model of original invisaflow before installation: >----------

Model of trial bend 1: >------^---
Model of trial bend 2: >------v---
Model of trial bend 3: >------^---v ( edge is bent to sit under the drip
edge)
 

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Discussion Starter · #5 ·
For the benefit of anyone who might have the same issue, I'm posting pictures of a solution I came up with after trial and error.

I bent the screen flat tops to create a valley. This allows rainwater to drop through the screen. I added a parallel bend at the shingle side, less than 1" in width. This lifts the shingles slightly and enhances the drop.

The next challenge was to duplicate the same bends across all 30 screens so they would mate. After using scribed lines on a flat piece of wood, I nailed a small trim piece on to align the screens consistently.

I'll add photos as soon as my iFPhone releases them from bondage.
 

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Discussion Starter · #7 ·
The adventure continues! Dry basement for months, paid to have new vapor barrier installed throughout crawl space. One month later comes a hard rain which seeps a bunch of water into the basement. I observed overflow from both gutters at the 2-story end of the house.

On close-up look at the gutters, I see shingles tented up, being pushed up by drip edge and gutter screens. This seems to match the area where the overflow was worst.

The first photo reveals what I charitably refer to as an "issue". The drip edge from here to the end of the house was a paid install by a gutter company. :vs_whistle:

The second photo is version 3 of my experiment to reduce overflow. I reduced the shingle overhang from 2" to 1" so it only goes 1/2" past the drip edge. This required pulling nails in 5 courses of shingles and reducing the reveal to 4-1/2". The gutter screen has been modified to a single 25 degree bend to create a valley. This worked along most of the 12 foot section, with water overrunning only at one spot.
:vs_mad:

I'm getting bids on a hired repair to address the overflow. One gutter co recommends 6" gutters. The next recommended adding a downspout.
Viewer suggestions are welcome!
 

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I am not an expert, I have only researched similar problem earlier this year and will offer my opinion.

I think you are on the right track. In that it looks like your shingles may overhang too far for the size of gutter. The overhang is a delicate balance and I have no real opinion on whether you need bigger gutters or rehung gutters or trimmed shingles.

You were on the right track to bend those covers, since you want the water to cascade and fall into the gutter instead of flowing over the top during a downpour. But I think the bent cover is still too large for your gutter, that it would be better to have ones that fit flush with the top of the gutter. Not connected to the roof line or drip edge. I believe the aluminum perforated guards are a more durable approach (Shur Flo or other brand) but I think the mesh style you have can work if the fit were better.

You mention overflowing gutters, was that from a clog or was the rain at such a rate that it could not clear the downspout? It should go without mention that even with these guards the gutter will need periodic cleaning (they surely would at my house). Another downspout may be needed depending on how much roof area is being handled, but of course that creates another work item of where to discharge the water.

I think there is some debate on whether 5" gutters are big enough, from what I gather most roof/gutter people think 5" is big enough if installed properly and the roof is not oversized. Otherwise 6" could be installed, but in your case it is probably your last option due to replacement costs.
 

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Discussion Starter · #9 ·
You mention overflowing gutters, was that from a clog or was the rain at such a rate that it could not clear the downspout?
I've been keeping the downspouts clog-free and clearing leaves and grit periodically. The overflow seems to be related to a combination of screen surface tension, excess shingle overhang and drip edge pushing up on eave shingles. And (just my luck!) it was mainly located at the two-story height end of the house where I hardly dare work on my 20' ladder.
:vs_balloons:
 

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Discussion Starter · #10 ·
.

Try the image aluminum guards. Replace one of these with the guard you have and see if it makes any difference. Look for 6" wide guard that's wide enough to slip under the shingles. Should go under the starter shingles.
Here are a couple of designs that seem to follow a similar philosophy but have features to, maybe, prevent overshoot. Both sit completely in the gutter on a near-horizontal plane. Both have wave features to prevent surface tension overflow.

Leaftek: https://www.amazon.com/LeafTek-Gutt...07FB4QBGQ/ref=cm_cr_arp_d_product_top?ie=UTF8

A-M Aluminum Guard: https://www.amazon.com/M-Aluminum-G...B96S/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1

Anyone have experience with these designs?
:glasses:
 

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Here are a couple of designs that seem to follow a similar philosophy but have features to, maybe, prevent overshoot. Both sit completely in the gutter on a near-horizontal plane. Both have wave features to prevent surface tension overflow.

Leaftek: https://www.amazon.com/LeafTek-Gutt...07FB4QBGQ/ref=cm_cr_arp_d_product_top?ie=UTF8

A-M Aluminum Guard: https://www.amazon.com/M-Aluminum-G...B96S/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1

Anyone have experience with these designs?
:glasses:
That is the style I was referring to earlier and planning to install on my gutters when they get replaced (again no first hand experience yet). Based on what I could learn from a few people who work daily with gutters there are two types of screens that are most recommended. Those 1) aluminum perforated and 2) micro-mesh. Both sat in the gutter to let the water drop in to them to minimize surface tension overflow.

The main differences between these two styles were that the micro-mesh are more effective at keeping the inside of the gutter clean but are more expensive. The micro-mesh by having smaller holes will keep the gutter cleaner but as the mesh fills up with shingle grit or decaying organic matter their effectiveness drops and if not careful about how they are installed the surface tension of water will be enough that water will overflow the top in a downpour. That in comparison the perforated might mean the gutters need some periodic cleaning, but the cleaning step will be more straightforward, and the overall water capturing ability higher. I think the right solution depends in part on the kinds of trees near you home, the size and shape of organic matter floating around your home, whether you have ever seen moss growing (as it will grow on top of the micromesh), etc.
 

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Discussion Starter · #12 · (Edited)
I'm in agreement that micromesh could require more frequent cleaning so I'm inclined to go with the perforated in-the-gutter styles.


Before I spring for different screens I decided to test the concept of the in-gutter screen. I bent the back edge of one current screen up to fit into the gutter against the drip edge rather than under the shingle.
The hose test passed with no overrun. Time will tell how well leaves and seeds blow free of the valley, but I have to sweep a few away anyway.

I just bought a square of shingles and new starter strip. I plan to continue reducing the overhang along the one-story end of the house, replacing the battered shingles as I go. The gutter person I hire will probably use the rest on the two-story section.
 

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Valleys are a challenge. Instead of a splash guard which tends to collect debris, I am planning to install one of those oversized corners to catch the larger flow of higher speed water that overshoots a normal gutter. I do not know all the common name of this part, but this is an example:
https://www.amazon.com/Extreme-5-inch-Aluminum-Inside-Miter/dp/B075WXZ9KH
Getting it covered will be another challenge.
 

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Discussion Starter · #14 ·
There are 249 pounds of shingles and starter sitting in my garage and I can hardly wait till Monday to use 'em.

Here is a photo of the overhang I plan to use. The shingle instructions are pretty specific. They say use 1/2" overhang over drip edge, 3/4" otherwise.
Either is way short of the 2" overhang installed on my house in 2010.
One roof estimator told me the 2" overhang is correct, ending almost over the middle of the gutter and bending down. I'm inclined not to agree.

1" overhang on my eaves, as in the photo, puts the shingle edge 1/2" past the drip edge. In theory this could bring water back to the fascia by capillary action. But I have cement fascia and soffit. The strip of duct tape I used to seal down the roofing paper over the drip edge I installed January 2019 still looks dry and undamaged.

Roofers, see any issues with my reasoning?
 

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Discussion Starter · #15 ·
... from what I gather most roof/gutter people think 5" is big enough if installed properly and the roof is not oversized. Otherwise 6" could be installed, but in your case it is probably your last option due to replacement costs.
Here are my calculations of gutter size requirement. I found this technique on This Old House.com and used 10-year worst rainfall data from (a gutter co's web site, guess I better recheck that data with NOAA).

On the half roof that faces South-Southwest: Roof area is 13.75sf x 14.9sf=(nominal 1125sf) Pitch factor for 5-12 pitch roof is 1.05. Ten-year rain maximum intensity is 7.3in/hr for Atlanta, GA region. Adjusted worst-case runoff area is AxPFxI =8625sf (nominal,rounded up) or 8563.4sf to 1 decimal place.

A 5" K-style is said to be able to handle 5520sf with two downspouts; add 1200sf after I add a third 3x4" downspout, for a total of 6720sf. Looks like my gutter is undersized for the back half of the house by this method. (A 6" K-style is said to handle 7960 adjusted sf.)

A roofing co's web calculator provided that 7.3inch/hr intensity number but concluded 5"K style was enough. A 1926 paper on naldc.nal.usda.gov lists an Atlanta maximum at 2.93" over 49 minutes for 3.6 in/hr. This is less than half of the figure I used above.
 

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Here are my calculations of gutter size requirement. I found this technique on This Old House.com and used 10-year worst rainfall data from (a gutter co's web site, guess I better recheck that data with NOAA).

On the half roof that faces South-Southwest: Roof area is 13.75sf x 14.9sf=(nominal 1125sf) Pitch factor for 5-12 pitch roof is 1.05. Ten-year rain maximum intensity is 7.3in/hr for Atlanta, GA region. Adjusted worst-case runoff area is AxPFxI =8625sf (nominal,rounded up) or 8563.4sf to 1 decimal place.

A 5" K-style is said to be able to handle 5520sf with two downspouts; add 1200sf after I add a third 3x4" downspout, for a total of 6720sf. Looks like my gutter is undersized for the back half of the house by this method. (A 6" K-style is said to handle 7960 adjusted sf.)

A roofing co's web calculator provided that 7.3inch/hr intensity number but concluded 5"K style was enough. A 1926 paper on naldc.nal.usda.gov lists an Atlanta maximum at 2.93" over 49 minutes for 3.6 in/hr. This is less than half of the figure I used above.
Interesting that the calculator uses rainfall per hour, rather than say 15 minutes. As usually the peak intensity is for a shorter period of time.

I believe another factor to consider in gutter size are any obstructions such as a chimney or skylights. For instance, a section of gutter directly below the edge of my skylights is prone to over flowing in a downpour. I have been thinking of installing a 6" gutter on that size of my house, to better handle it. But perhaps an extra downspout installed near this point will be a better solution (compromise) to keep all the gutters the same. Your post is causing me to consider that option.
 

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Discussion Starter · #17 ·
After a couple of days work in cooler Fall weather, the gutter screens are functioning better on a garden hose test. The shingle overhang is 7/8" and I lined the first three courses up straighter than they were when installed. I replaced the worst damaged shingles showing holes or pitting with new Certainteed XT25.
I ordered some new hidden gutter hangers. Some of last years' hangers are too tall for the new screen shape.

After some parts get here I'll have functioning coil nailers to secure shingles with.

:glasses:
 

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