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The downspouts on a house are vital to protecting the home from damaging water run off. Roofs are pitched to direct water downward into areas like valleys, and eventually over the edges into the gutters. But if that water is not channeled correctly out of the gutters and safely away from the home, all the effort put into proper roofing for water runoff would be wasted and the results for the home can be devastating.

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Downspout Extension

We will consider the following points in regards to downspouts:

  1. Number of Downspouts Placed.
  2. Proper Positioning of Downspouts.
  3. Correct Downspout Size

    1. Number of Downspouts Placed

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    Having the correct number of downspouts for the length of your gutters is crucial. Without the right number of downspouts water can back up in the gutters preventing proper flow. The typically accepted rule of thumb is not to go over 40 feet without adding a downspout.  

    There are however, reasons to consider placing downspouts significantly closer together than every 40 feet. The first reason would be if the roof itself was a very elevated pitch. In the case of high pitched roofs the water runs off faster making it necessary for the gutters and consequently the downspouts to remove water at a faster pace. The other main reason for this would be if the roof was very large. This would mean a much more significant amount of water would need to be disseminated the larger the roof became. Again, resulting in the necessity to move water away quickly.

    2. Proper Positioning of Downspouts

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    Proper Downspout Water Flow

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    Standing Water From Improper Pitch

    The placement of a downspout is critical to its proper performance. One can easily go purchase a standard length of downspout and let the water drain where ever the downspout stops. But this method is risky if certain factors are not considered.

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    Water Around Foundation of the House

    Understanding the pitch of the land around your house is pertinent when determining how far away the downspout must travel to safely disseminate the water. When a house is built it’s actually like building a well, because a hole is dug in the ground first to lay the foundation in. If that hole is not filled correctly and the house brought up to the right level water will run downhill towards the house instead of away from the house. As a result if the downspout is to short the water will simply backslide directly into the path of the foundation, risking foundation damage.

    The other thing to consider when determining which area of the house to place a downspout is not just the pitch, but the condition of the ground around the house. It is a good idea to look for any signs of mushy ground that gives away and is overall not secure. Things like dips, depressions and cracks in the soil along with ponding of water are all important things to watch out for. Symptoms like this can be anything from signs of a sinkhole to just a low spot in the ground. But no matter what it is draining water into an area like this is not good and could certainly make it worse. When placing downspouts it is best to secure the downspout to sturdy and dry looking ground area to help assure the landscape is able to take on the excess amounts of water.

    3. Correct Downspout Size

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    Different Downspout Sizes

    The size of a downspout can greatly determine where and how often a downspout needs to be placed. Standard sizes include 2×3 or 3×4. The advantage of the larger sizes like the 3×4 is that they are harder to clog and can handle about twice the amount of water. The opening to a 3×4 (where it attaches to the gutter) is larger than that of the 2×3, which also means a bigger space that is harder to clog with debris.

    Going back to the idea of steeply pitched roofs or very large roofs, it is certainly recommended to go with the larger sized downspout to assure the extra load of water can be handled. Even the type of roof plays a role in the downspout type. Metal roofs for example experience water run off faster than asphalt roofs do. Gutter type is also a part of the consideration in that half round gutters are shallower, so they recommend a larger downspout when using them too.

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