Installing rain gutters on your roof is the first step in managing roof runoff. Now that there isn’t water dripping on your head when you step under the eaves, it’s time to consider where that roof water goes when it enters your gutter downspouts.
Downspouts are there to direct excess water away from your house foundations. Having large amounts of water pooling around your foundation is never a good thing and may lead to water damage in the long run. So your downspouts must extend far enough away from your home. Additionally, downspouts can add to the aesthetic of your home with one of these decorative downspout ideas.
The question remains; how far should downspouts extend from your home? Read on to learn everything you need to know.
The Short Answer
In a world where all houses are the same, built on the same site, the answer is 4 feet. Your downspouts should extend an absolute minimum of 4 feet away from your home.
As you know, not all houses are the same. And not all houses are built on the same site either. For this reason, there isn’t an answer that applies universally to every situation. The real answer is; it depends.
It depends on the type and quality of the soil surrounding your home. It depends on the site your house is built upon and which way it slopes. It depends on your building codes, and it depends on your climate. So it’s highly likely you’re going to need a downspout extender when installing your downpipes.
So let’s dive a bit deeper and give you a useful answer, shall we?
Everything Rolls Downhill
One of the first things to consider is which way does the ground slope around your house? Even on flat land, the strip of ground that’s right up against your foundation should have a gentle slope away from the house, but this slope won’t affect your drain pipe.
Which way does the general landscape slope? Using this to your advantage can be one of the most effective ways of directing water a safe distance from your home to prevent thousands of dollars of damage to your basement walls.
If possible, extend your downspouts to the crest of a slope that falls away from your house. This way water that leaves the downspout continues moving away from your house.
If your downspout extensions drain into the base of a slope angled towards your house, water will do a u-turn after leaving the downspout and pool around your foundation, which is what we’re trying to avoid.
If you’re unsure, you can mimic heavy rain by using a garden hose to track the path of water when it lands near your house. Direct the stream of water from the hose to the spot where you want your downspout to end. Watch the path of the water and note the direction it flows. Use this information to make an informed decision about the position of your downspouts.
The next factor to consider is the type of soil that surrounds your house. Some soils absorb water, some resist water absorption, and some drain freely, allowing water to move through without being absorbed.
Soils that have a high clay content tend to resist water absorption. It is due to the shape of clay molecules and the way they organize themselves when they come into contact with water, but that’s a topic for a different article.
If you have a high clay content in the soil surrounding your house, you won’t have to worry too much about excess water being absorbed and wicking into your home. So your downspouts can be shorter.
However, this excess water runoff still needs to go somewhere, so make sure to direct water away from your house.
Sandy soils tend to hold onto water a lot more. It means that if your downspout deposits water into an area with sandy soil, the water is likely to pool in this location if there is no slope. If your home is surrounded by sandy soil, you need to extend your downspouts further away from your home.
Many different soil types exist between the two extremes mentioned above. For this reason, observe the way the soil behaves when it rains and make an informed decision with that information.
Remember The Law
Your local building code will have information about the legal requirements for downspout length. It is useful information to make sure your house is code compliant.
Local building codes also take local factors into accounts, such as predominant soil type and the local climate. It can be a useful way to get a better idea of what factors you’re dealing with.
The absolute minimum distance that your downspouts should extend from your home is 4 feet. That’s the starting distance before you consider all the different factors that exist in your home and property.
Other factors that influence this decision include slope, soil type, building codes, and the local climate. Your building professionals in your area should have a good grasp of all the information above and may be able to guide you through the decision-making process.
Has this post answered your question? Comment below if you have any more questions.