Guide To Gutter And House Drainage Distances: 7 Useful Options
In areas that experience high rainfall throughout the year, effectively moving water away from your home is critical. Unfortunately, many homeowners are unaware of the importance of protecting their foundations from water infiltration. Gutters, downspouts, and drains are critical components of protecting your home’s foundation from water infiltration.
In general, your downspouts should drain at least four to six feet away from the foundation of your home. If you have a basement, ten feet is a better distance. You should also ensure that your gutters, downspouts, and drains are sized properly for the size of your room. You should perform regular maintenance to keep your gutters working properly.
There are many tricks and tips you can use to help protect your home from the damages caused by rainwater invasion. Take a moment to read through our seven options that will help ensure that your home is prepared for the next big rain.
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What Really Happens When It Rains?
It is important to understand what is happening on your roof, in your gutters, and around your foundation when it rains. Your roof, downspouts, and gutters are a system that helps keep water out and away from your home. Water infiltration into your home comes from three sources.
- Water can enter your home through the roof if your roofing material is damaged or worn.
- Water can damage your home if the gutters are not properly sized and installed correctly
- The rainwater may not be flowing away from your home because of poor landscape design. Improper slope in your landscape can leave you with a damp foundation, wet crawlspace, or standing water in your basement.
How Much Water Are We Talking About?
It can be surprising how much water actually runs from your roof during a rain event. According to the American Society of Rainwater Catchment Systems, every 1,000 square feet of roof will catch 623 gallons of water during a one-inch rain event. The average 2000 square foot home must deal with 1,264 gallons of water cascading off the roof around the foundation.
This is a lot more water than most people estimate. The average 4 person household in the United States uses approximately 160 gallons of water per person per day. A one-inch rainfall produces on a 2000 square foot roof catches enough rainwater to supply this average family for two days.
What Effect Does This Water Have on My Home?
The effect of this water in the soil around your home can be devastating. Just a few of the possible consequences of allowing rainwater to fall close to your home’s foundation include:
- Moisture infiltrates into your home when the perimeter foundation stays wet. This can lead to mold and mildew growth that can become a health hazard in your home.
- The crawl spaces associated with pier and beam foundations can remain damp for months after heavy rain. This damp space can be a source of mold, mildew, and insect infestation if it doesn’t dry.
- The rainwater may find its way into a basement through the basement walls creating havoc with humidity, water damage, and flooding.
- Over the long term, foundation damage can result such as subsistence, cracking, or heaving.
Unless this collected rainwater is moved away from the foundation of your home, you may already have problems. Unfortunately, many rainwater problems are only noticeable after much damage has been wrought. Taking a proactive response by properly installing gutters and downspouts on your home is one of the best means of protecting your investment.
Seven Options to Protect your Home from Rainwater Incursion
Protecting your home from the effects of water infiltration is important for your home and your family. Hopefully, your home is already guttered with downspouts strategically spaced to handle the water flow from your roof when it rains. If not, before you begin any other plans, you should consult with a qualified gutter installer to discuss installing gutters on your home.
These seven tips can help make your gutters and downspouts more effective at protecting your home and its foundation from water infiltration and damage. You may already be using some of these tips. If so, congratulations. However, you should look at the rest of our ideas to help protect your home’s foundation.
Check the Size of Your Gutters
It isn’t unusual to find homes with installed gutters that aren’t sized large enough to handle the amount of water from the roof. Downspouts must also be the correct size and placed properly in the gutter system. If your gutters and downspouts are too small for your roof size, they may overflow and allow water to sill down next to your home’s foundation.
In general, the most common styles of gutters installed on homes are sized according to this chart.
| Style of Gutter | Size of Gutter | Effective Roof Square Footage |
| K-Style | 5 Inch | 5,520 Square Feet |
| K-Style | 6 Inch | 7,960 Square Feet |
| Half-Round | 5 inch | 2,500 Square Feet |
| Half-Round | 6 inch | 3,840 Square Feet |
When calculating the effective roof square footage, you must consider the pitch of the roof and the local maximum rainfall intensity. The common adjustments used to calculate effective roof square footage are:
- 12 in 12 Pitch or higher use a 1.3 adjustment factor
- 9 – 11 in 12 pitch use a 1.2 factor
- 6 to 8 in 12 pitch use a 1.1 factor
- 4 to 5 in 12 pitch use a 1.05 factor
- Flat to 3 in 12 pitch use a 1 factor
For example, a 2,000 square foot home in Seattle, Washington, would yield this calculation with a roof slope of 6 in 12.
| Roof Collection Are in Square Feet | 2,000 |
| Roof Pitch factor (6 in 12 pitch) | 1.1 |
| Effective Roof square Footage | 2,200 square feet |
| Local Maximum Rainfall Intensity | 1.6 |
| Adjusted Effective Roof Square Footage | 3,520 Square Feet |
In this case, a 5-inch K-style gutter or a 6 inch half round gutter would be required to handle the expected runoff from the roof in Seattle, Washington.
Do You Have Enough Downspouts and in the Right Places?
The usual practice is to place downspouts so that they drain no more than 35 feet of gutter. Gutter downspouts should be sized properly as well. It is generally accepted that downspouts of these sizes can carry support this much effective roof square footage.
| Style of Downspout | Size of Downspout | Maximum Roof Square Footage per Downspout | Minimum Number of Downspouts per 1,000 square feet of roof |
| Rectangular | 2 by 3 inches | 600 square feet | 2 |
| Rectangular | 3 x 4 inches | 1,200 square feet | 1 |
| Round | 3-inch diameter | 706 square feet | 2 |
| Round | 4- inch diameter | 1,255 square feet | 1 |
The configuration of your gutters around the eave of your roof also contributes to the number of required downspouts. Consult with a trained gutter installation specialist to get the best answers for your gutter and downspout needs.
Is your Landscape Working Against You?
One of the most important aspects of getting and keeping rainwater away from your foundation is your landscape design and the slope of your property. Ideally, your home should sit on the highest point of your lot. The land should slope away from each side of your house to promote good drainage.
Unfortunately, we rarely find that perfect spot. There are almost always some compromises in slope and drainage. Wherever possible, your lot should slope away from your foundation enough to prevent rainwater from standing close to your foundation.
Landscapes should be designed with the same thought in mind. Your landscape should have a buffer zone between your plantings and foundation, preventing water from standing and pooling. This can be a huge problem if your lot has areas where the slope directs water against your home. You should consult with a reputable landscaper or excavation contractor about regrading this portion of your landscape for proper drainage.
Are your Gutter and Downspouts Taking the Water Far Enough from Your Home?
You may have the best properly sized and installed gutters and downspouts available. However, suppose the downspouts don’t put the collected rainwater in the right spots far enough from your foundation. In that case, you may be making the situation worse rather than better.
If your downspouts terminate only inches from the foundation of your home, the situation may be creating a bigger problem in general. Your downspouts should terminate at least four to six feet away from the foundation of your home. The water should be deposited in a spot that has adequate drainage away from your foundation to keep the water from backing up.
There are several ways to make sure the collected rainwater is placed far enough away from your foundation. Some options to consider include:
- Downspout Extensions – Adding an extension to your downspouts is one good and inexpensive method for making sure rainwater is placed at an appropriate distance from your foundation. This is particularly effective if you have landscape beds around your home. The extensions can be run to the outside edge of the beds to place the water to drain away properly.
- Roll Up Downspout Extensions – If you don’t have landscape beds and you don’t want a long downspout extension on your lawn, there are some solutions. Perhaps the best is the roll-up downspout extensions. These extensions are made of a flexible pipe material that can be rolled up and tucked under a downspout opening. When it rains, the force of the water in the downspout unrolls the extension. This puts the water away from your home. The downside to these roll-up extensions is the need to go out after a rain and re-roll them again.
- Underground Downspout Extensions – In some cases, adding an underground extension to carry rainwater away from your home may be a solution. Underground downspout extensions use a plastic pipe, usually 4 inches in diameter, buried beneath the soil. The downspout extension terminates away from the house using a specialized fountain drain opening to disperse the water onto the landscape. These are very effective systems but can be a bit expensive to install.
- Install a Rain Catchment System – Some people opt to collect the rainwater coming off their roof for use in their landscapes and gardens. These systems can be designed to put the collected rainwater in tanks for later use and direct any overflow to a location away from your home.
A French Drain May Help with Moving Water Away from your Foundation
In some cases where your landscape is working against you, a French drain may be a solution. If your home sits on a sloped lot higher on one side, you may have water coming into your foundation from above you. It may be impossible to redirect your downspouts or regrade your lot to prevent this kind of water infiltration.
In this case, installing a French drain on the perimeter of at least a portion of your home’s foundation may be the solution. A French drain uses a perforated plastic pipe laid in a trench along the perimeter of your foundation. The perforated pipe is protected by a barrier cloth and layers of gravel. This construction allows water to enter the drainpipe and be taken away from your foundation.
If you think a French drain may be a solution for water infiltration into your home, you should find an experienced contractor with French drain design and installation. The depth of the drainpipe, size and construction methods are critical for French drains to operate properly. Typically, installing a French drain is not a do-it-yourself project.
Design Your Landscape to Manage Rainwater Effectively
Believe it or not, your landscape design can greatly impact how rainwater affects your foundation and home. A well-designed landscape can actually work with your gutters to move the rainwater away from your home. You can also incorporate designs that will make use of the redirected rainwater in your landscape. These designs can improve the look of your landscape and save money by utilizing the rainwater in more efficient ways.
A landscaper who is familiar with designing and installing rainwater management landscapes is a good option. For more information about rainwater landscape management, you can visit the ARCSA website at this link for more information and help.
Maintain your Gutters and Downspouts to Ensure the Optimal Operation
Like anything else, gutters and downspouts require a certain level of maintenance and care to operate properly. Unfortunately, many of us ignore our gutters and downspouts until a major problem occurs. A bit of TLC regularly can prevent many major problems that can lead to damage to your foundation or home.
- Clean Your Gutters At Least Twice a Year – Your gutters need to be cleaned and inspected at least twice a year. If you have large trees in your landscape, the frequency of maintenance on your gutters should probably go up.
- Install Leaf Guards on your Gutter – Your maintenance time and effort can be cut down considerably if you install a high-quality leaf guard on your gutters. Leaf guards prevent your gutters and downspouts from becoming clogged with leaves and other organic matter, ensuring a free flow of water in your gutter system.
- Watch for Leaks and Other Damage to Your Gutters and Downspouts – Weather, wind, animals, and accidents can damage your gutters and downspouts. This kind of damage can lead to leaks allowing water to infiltrate your home. A regular routine of inspections can help prevent larger problems.
Maintaining your gutters and downspouts regularly is just as important as doing routine maintenance on your HVAC system. Your gutter and downspouts perform a vital function to protect your home and foundation from damage. It pays to spend a little time and effort to maintain the gutters and downspouts properly.
I Notice that My Gutters Back Up and Overflow. What is the Problem?
Gutters that overflow and allow water to shower down around your home’s exterior may be suffering from several problems. You should check for these issues to ensure that your gutters and downspouts operate effectively.
Clogged Downspouts
A clog or blockage in a downspout can cause water to back up and overflow the cutters served by the downspout. Blockages can be caused by several things
- Damage to the downspout can cause debris to hang up in the downspout, causing a blockage. If you can see bends, bulges, or other damage to the downspout, you may have an issue with debris in the downspout.
- Animals often find downspouts a convenient place to build a nest during dry times. Nests can cause serious damage to a downspout and will cause water to back up and overflow the gutter
- If you use roll-up downspout extensions, make sure they operate freely. It is not unusual for debris from your landscape to interfere with the correct operation of these downspout extensions.
It may be inconvenient, but the best way to identify a downspout problem is to walk around your house while it is raining. It is easy to spot downspouts that are not running freely and operating properly.
Clogged Gutters
Gutters can quickly become clogged with leaves and other debris during the growing season. During fall, this is an especially acute problem that must be attended to regularly. If your gutters don’t have the proper slope or have sagged, you can find dust and dirt accumulating as well. I have seen gutters so filled with dust that plants take root in the gutters.
Keep your gutters clean and in good repair. Install leaf guard to keep debris from accumulating in the gutters. Watch for sags in your gutters where water and debris may stand and accumulate.
Routine maintenance and attention will help alleviate many of these problems.
Proper Slope on your Gutters
Gutter systems depend on gravity to move the water effectively to the downspouts. If your gutters don’t have the proper slope, you won’t get the most efficient water movement. This can cause the gutters to back up and overflow.
Generally, the guttering should have a one-quarter inch per ten-foot run slope for the best water movement. If your guttering doesn’t run well, you may need to have a gutter specialist come and check the slope of your gutters.
Proper Gutter Size
As we discussed earlier, an improperly sized gutter may not have the capacity to move enough water from your roof. Improperly sized downspouts or not enough downspouts can cause water issues as well. Using a few simple calculations can quickly determine if your gutters can remove the rainwater effectively.
If you have any questions, consulting with a gutter specialist or someone familiar with rainwater management designs can help you determine if your gutters and downspouts are adequate.
What Kind of Guttering is Best?
There is no one answer to this question. The best guttering and downspouts for your home are those that get the job done efficiently and satisfy your aesthetic and budget needs. In general, we recommend these minimums for residential guttering.
- Ensure the guttering is properly sized and installed to handle the amount of water you can expect to flow from your roof.
- If possible, use a company to install your gutters that custom builds continuous guttering for your home. This eliminates seams and joints, which can dramatically decrease the amount of maintenance your guttering will require.
- Aluminum guttering is less maintenance intensive than steel. It is also budget-friendly. Other materials such as copper are long-lasting as well, but very expensive. You can get continuous aluminum guttering in colors to match the exterior of your home.
- Specify gutter hangers that screw in rather than a nail in. These types of hangers typically have a longer life and stay in place better.
The guttering that is best for your situation may be entirely different than the house across the street. A gutter installation professional can give you the best advice about your gutters’ materials, installation, and maintenance.
Do You Need Foundation Drainage Installation or Replacement?
Get free, zero-commitment quotes from pro contractors near you.
Keeping the Water Away from Your Home’s Foundation
In the end, the goal is to keep the collected rainwater away from your home’s foundation and basement. As much as we all like the rain, when it gets into your home, it can cause a wide array of problems from mold and mildew to structural issues that can cost thousands to repair. Installing and maintaining the right gutter system can prevent these kinds of problems
Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.
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