How to Handle Roof Runoff Without Gutters (2024)

Heavy rains that cause rainwater to fall from the roof directly onto the ground can cause erosion, landscaping and foundation problems around a home. Erosion can occur anytime rainwater is uncontrolled. Uncontrolled falling water can impact the ground with enough force to create a ditch, washing away the topsoil. If your home does not have a gutter system, you are likely dealing with frequent water damage and it’s critical to handle roof runoff that may occur.

In this article, I’ll discuss how homeowners can manage roof runoff without the benefit of gutters. I will cover both innovative products and landscaping techniques to control water flow.

Why Are Gutters Missing From My House?

It is quite common to drive down any neighborhood and see homes with rain gutters and downspouts. Many homeowners assume that traditional gutters will be included on a home; however, some homes lack this important drainage system.

Most homes with missing gutters are either in a state of disrepair or under construction. In areas where gutters are a necessity, they are usually one of the last projects to get installed. Ladders can scratch the paint on new gutters, so installing later protects the gutters from tools that could damage them.

For homes in disrepair, wood that has rotted is usually the culprit. Gutters often detach from the fascia board (the horizontal board directly under the roof edge) because the board has rotted and will no longer support a fastener.

In some cases, both the fascia board and gutter will fall off, leading to water damage inside the home. If this occurs, the rafter tails (the end of the rafter that the fascia board attaches to) will also begin to rot, leading to expensive roof repairs.

What Can I Do to Handle Roof Runoff Without Gutters?

Fortunately, effective methods to manage roof runoff are available. Some solutions will require additional products, like chains and louvers to lessen the impact of runoff. Other solutions will deal with the aftermath, such as installing a french or channel drain to direct the water away from the foundation. Here are the most common solutions and how they work:

Rain chains provide the water with a surface to travel on, preventing the water from gaining momentum as it falls. Rain chains will always be corrosion-resistant and usually made from either aluminum, plastic, or galvanized steel. Rain chains are usually suspended from the lowest corner of the roof and dangle over either a splash block or a water-collecting barrel.

Building codes require that the dirt around the foundation slopes away from the home, typically 6” of fall over 10’ of travel. However, this code assumes the presence of gutters and really only deflects water falling directly to the ground as rain or snow. Increasing the slope of the grading will allow the runoff to drain away faster, preventing the water from backing up towards the foundation.

A french drain is a common addition to landscaping, and is used to channel water from one location to another. French drains use a combination of trenching, pipe, and gravel to create a channel in the ground that can be completely hidden. After the french drain is installed, topsoil or mulch covers it, allowing rainwater to be absorbed and slowly deposited into the drain.

To build a french drain, a narrow trench (about 12” deep) is placed about a foot away from the foundation and the bottom is covered in coarse gravel. Next, a perforated pipe (usually Schedule 20 PVC) is wrapped in landscaping fabric to prevent roots from blocking the pipe. It is then installed in the trench with the perforations in the pipe pointing down. As water is collected in the trench, it rises into the pipe through these perforations and is carried away by gravity. 

There are instances where the roof runoff lands on concrete instead of the ground. The most common solution for this is to install a channel drain to collect and direct the runoff away from the home. As the name implies, a channel drain consists of both a channel and a grate, which are let into the concrete pad using a concrete saw. Channel drains are often located directly in front of a garage door to prevent a backward-sloping driveway from directing water into the garage.

Channel drains require a groove cut into the concrete at its lowest point, which can be determined by pooling water. The channel section is concreted in, and at this stage, performs the function of a gutter. To complete the installation, the included grate snaps onto the channel to allow a vehicle to pass over it without damaging either the vehicle or the drain. Because the grate is slotted, it allows runoff to drain through the slots, while preventing leaves and other debris from clogging it.

Louvered diffusers are a different option from gutters. They are installed on the fascia boards in the same location gutters would normally appear. Louvered diffusers are mounted a few inches below the edge of the shingles and prevent sheets of roof runoff from striking the ground, causing erosion. Louvered diffusers are usually made from ABS plastic or corrosion-resistant metal, like aluminum or galvanized steel.

Instead of collecting the water, louvered diffusers allow the water to pass through, but break up the large sheets of water as it leaves the shingles. As the name implies, this diffuses the water into smaller, less damaging droplets. Because this allows the ground to absorb the water more slowly, it prevents water from flowing and creating a ditch.

A very effective method of controlling roof runoff employs a rain diverter. A rain diverter is a form of flashing and installed on the roof itself instead of the fascia board. Rain diverters are usually made from aluminum or galvanized steel and include a mounting tab. 

Rain diverters are formed from thin gauge metal and bent down the center to about a 90 degree angle, which catches the runoff and redirects it away from the roof edge. For installing a rain diverter, one side is placed under a course of shingles and secured with roofing tacks. The other side of the diverter can then extend upward from the roof and divert water in either direction. It’s also not very complicated to make a rain diverter if you are interested in one.

As mentioned earlier, gutters are rarely installed early in new construction, yet the roof is one of the first projects. Roof runoff is especially bad at this stage of construction because there is no grass or grading to control rainwater. Often, this is why construction sites become a muddy mess.

When possible, pro builders will install 6mm thick builder’s plastic directly under the runoff to absorb the impact of the falling water and prevent erosion. Builder’s plastic (6mm) is the same material used in crawl spaces as a vapor barrier, so it tends to already be on the jobsite. You wouldn’t want to use this method permanently, as it would kill any vegetation underneath it. However, this method works great as a temporary measure and can be easily removed later when the gutters are installed. 

Final Thoughts

Effectively managing roof water runoff without gutters is crucial for homeowners who want to protect the home’s foundation and prevent erosion. Utilizing solutions such as rain chains, French drains, channel drains, louver diffusers, rain diverters, and temporary builder’s plastic can mitigate the impact of roof runoff. Many of these are DIY solutions.

By implementing these techniques, you can control water flow and safeguard your home’s structural integrity. I recommend properly addressing any roof runoff issues. This preserves your home’s landscape but also prevents costly damage, ensuring your property remains in excellent condition for years to come.

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