Our Best Customer is an Educated Consumer

Topic: Proper Gutter Installation

Expert: Michael J. Owen
Date: 3/6/2007
Subject: roof & drip edge


I had a roof installed by my son. I had new fascia boards installed along with soffits and drip edge. I then had new gutters and downspouts installed. The reason for my question is, when it rains water gets behind the gutter and runs down the fascia boards. When I called the person who did the gutters he said the roof overhang was not out far enough for the water to go into the gutters. The gutters were installed in front of the drip edge. My son says that the gutters should have been installed behind the drip edge and that is why the water is coming behind the gutters. Who is right and how can it be corrected?


Hi Ron. Your son is absolutely right. "Been there and done that". Three choices to remedy the problem:
1. Move the guttering up behind the drip edge.
2. Install a metal "flashing" from under the drip edge and just inside the gutter.
3. Pull out the drip edge so that it overhangs into the back of the gutter.
Water will run down the roof and then backwards as it runs over the edge. This may not happen if the roof has a steep slope.
Hope this answers your question.

Roofing Experts Guide To Properly Installed Gutter

Gutter Material: Aluminum




.022 Thickness




.027 Thickness (Most commonly used.)




.032 Thickness




Downspout Material: Aluminum




.019 Thickness (Most commonly used.) 2x3 and 3x4 downspout




.024 Thickness   3"x4" downspout more common but available in 2x3 also.




Spikes & Ferrules: Aluminum




Smooth spike or Striated




Spiral spike




Ring shank spike




Hidden Hangers: Aluminum 




hidden hanger secured with nails.




hidden hanger secured with a # 10 x 1 1/2" screw




hidden hanger secured with a # 12 x 2" screw




Hidden Hangers & Spike: Spacing
















Gutter Slope:
 A 1" to 2" slope in  40 foot. NOTE: A gutter installed level will drain because water levels itself, however you will not have any water flow to self clean the gutter. To much slope does not look good and you loose some of the gutters holding capacity.
   Example: A gutter sloping 3 1/2" in a run has lost 1/2 of its holding capacity, in a short heavy down pour the water at the high end of the gutter will be nearly to the bottom of the gutter and at the downspout end (Low end) the water will be overflowing the top of the gutter, Remember?, water levels itself.
    Summary: Try to strike a happy middle, some slope for cleaning but not to much.

Downspout capacity:
2x3 Downspout will drain 600 sq. ft of roof area.
3x4 Downspout will drain 1200 sq. ft. of roof area.
Gutter Capacity:
One foot of 5" K-Style gutter holds 1.2 gallons of water.
One foot of 6" K-Style gutter holds 2.0 gallons of water.

Gutter placed behind the drip edge.
This is a important part of installation on homes of 3/12 and 4/12 pitch roof. Water will suck back (capillary action) on the roofing material and run down the face board and behind the gutter. (causing damage to the face board over time) The basic knowledge and understanding of capillary action of water was the founding principle that the inventor Robert Demantini used in producing the well known product "GUTTER HELMET" which started a revolution in gutter cover industry spurring dozens of different models of gutter covers we see on the market today.
Steeper sloped roofs do not have this problem and in some cases the singles may overhang the drip edge and droop down into the gutter thus eliminating the problem . Strip flashing must be used to bridge the gap between the drip edge and the back of the gutter if the gutter runs below the drip edge at the lower end of the gutter run.  Good luck in getting a shoddy gutter company to come back and fix this problem, because it will require reinstalling the complete gutter system or installing flashing. So beware and insist that it be done!


Proper Installation of Seamless Gutters


At one time I read an article about proper installation of gutters. The only way we install gutters is to carefully cut each side of drip edge (also known as the cap) and insert the seamless gutter directly behind and up as far as it will go.  We then use a level giving it the slightest amount of pitch allowing the water to drain properly.  Other gutter installers say you do not have to install the gutter directly behind the drip edge but below it and we notice that other companies install the gutters using the "one by" as their guide.  As far as we are concerned, this type of installation is "decorative" as it only catches the water when it drizzles however heavy rain water overshoots the gutters when installed this way.  

We explain to customers when installing directly behind the drip edge, the installer must carefully move the drip edge so as to not loosen the tile otherwise it could ruin a roofing warranty and carefully installed gutters do take far more time to do then a shoddy job which is why properly installed gutters are more expensive.  I would greatly appreciate your response and notify me as to when I could expect to see a printed response.  Too many shoddy companies try and sell customers the idea that it is not necessary to install gutters DIRECTLY BEHIND THE DRIP EDGE BUT BELOW.


Hi Arthur. It has always been my understanding that the gutters should be up behind the drip edge and sized correctly to catch all the run off water. I have seen jobs where the gutter is under the drip edge and, over a period of time, the fascia boards have rotted out. You are correct in saying that it does take more time and therefore, could cost a little more. You are also right that the drip edge should not be bent too much to allow a valley to form where the drip edge is up and under the shingles. I do not know of any publications etc. which refer to this subject. You could possibly try Bob Villas web site. Hope this helps.

The following Question and Answer came from the Roofing Expert at All Experts


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