How Do I Control My Home’s Rain Runoff?

By Vernon Trollinger, June 26, 2017, Home Improvement, Hurricane Prep, Save Money

While most homeowners love their homes, not every home is perfect. There are one or two things the homeowner would like to change, such as an outdated bathtub for a new walk-in shower or updating the look of their kitchen. And then there’s occasional “uh-oh” of the unexpected repair. We’re going to identify several projects and some of the ins and outs of what you can expect.

How Do I Control My Home’s Rain Runoff?


How Do I Control My Home’s Rain Runoff? | Bounce Energy Blog

Last year, Texas State Climatologist, Professor John Nielsen-Gammon, confirmed the increasing instances of extreme rainfall in Texas over the past 100 years. Houston in particular has seen an awful lot more.

For homeowners, rain runoff, especially from their roof, can pose major problems:

Overflowing gutters can eventually turn into major repair problems. Consider that a single storm that drops one inch of rain on a 1155 square feet (25 x 46.2) roof produces about 60 gallons of water. Overflowing gutters can dump several gallons of water down the side of your home. Much of it will penetrate the siding and get into the sheathing. Repeated occurrences can trap moisture in the wall and cause the framing to rot, grow mold, and lead to expensive repairs. Rain water can also seep into the crawlspace under your home where it can increase your home’s humidity and possibly lead warping floors, wood rot, and mold problems.

Downspouts are supposed to take rain water from the rain gutters to the ground and direct it away from the house. If your home’s downspouts don’t move water away from your home far enough, you might be faced with water damage to the siding, along the foundation, and water getting trapped inside your crawlspace. Additionally, rain water can pond in low-lying areas and if left alone can become nurseries to disease-carrying mosquitoes.

How Do I Control My Home’s Rain Runoff? | Bounce Energy Blog

Where to Start

Start off by cleaning out any clogged rain gutters and clogged downspouts. Install metal or vinyl mesh covers that keep leaves and other debris from getting into the gutter. Also be on the lookout for holes and disconnects as well as areas where water may have damaged the fascia board behind the rain gutter. Because most rain gutters are screwed onto the fascia board, rot from water damage can lead to whole sections of the gutter pulling free.

Next, watch how your roof and down spouts handle run off the next time there’s a real good rain storm. If rain water is still overflowing from the rain gutter, then you should consider installing another downspout. A roofer’s rule of thumb is that there should be one downspout for every 35 to 40 feet (depending on the gutter and downspout size and who and where you ask). However, since incidence of extreme rainfall are on the increase, it may be wiser to install a downspout every 25 to 35 feet depending on gutter size and local conditions.

Installing a downspout is a pretty easy DIY project (assuming you’re comfortable with working on your roof):

  • You’re going to need to know the size of your existing gutter and downspouts.
  • Make sure the new downspout is the same size and runs down the same length as your home’s other downspouts.
  • Measure the lengths of the downspout pieces you’ll need and also the kinds of any elbows that you’ll need to match the look of your home’s other downspouts.
  • Put the downspout in an area that will drain the most water from the gutter effectively and will take it away from your home most easily.
  • For metal K-gutter systems, measure and mark the place or gutter outlet (or “pop”). Cut out this hole using either tin snips or a metal hole-cutting mandrel.
  • Attach the downspout sections so that the one above inserts into the section below.
  • Secure the downspouts to the side of your home with the proper straps.

How Do I Control My Home’s Rain Runoff? | Bounce Energy Blog


Ideally, the ground should slope away from your home’s foundation at least 3 inches for every 5 feet. Of course, it’s not always like that. There are ways to extend your downspout as far away from your house as possible by connecting it to either flexible downspout extensions or a black flex corrugated drain pipe. For many homeowners, long runs of drain pipe look ugly. In that instance, it’s often convenient to use perforated flex drain pipe which can be buried in a long, shallow trench lined with gravel. This drainage system carries water away from the home but lets it soak into the soil underground. Again, not all landscapes and soil are the same, so if it’s good idea to consider the different kinds of drainage systems that might work best for your home.

Landscaping is also an important and effective means of channeling rain runoff and can also provide a means of using all that water. Trees with limbs that over hang your roof can actually dump more water onto your roof during a rain storm. You can reduce that by cutting back those limbs. Trees and shrubs can be planted in low-lying areas where water collects. In fact, planting some varieties of raspberries and black berries that prefer moist areas will reward you every year with a summertime snack. Building swales and berms into the landscape can also help you better control runoff entering your property from your neighbors. For more information on how landscaping can improve runoff problems, talk to local landscaping professionals and county extension agents. They can offer you advice and planning help.

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A native of Wyomissing Hills, PA, Vernon Trollinger studied writing and film at the University of Iowa, later earning his MA in writing there as well. Following a decade of digging in CRM archaeology, he now writes about green energy technology, home energy efficiency, DIY projects, the natural gas industry, and the electrical grid.

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