Mastering Roof Inspections: Roof Drainage Systems, Part 2

by Kenton Shepard and Nick Gromicko, CMI®



The purpose of the series “Mastering Roof Inspections” is to teach home inspectors, as well as insurance and roofing professionals, how to recognize proper and improper conditions while inspecting steep-slope, residential roofs. This series covers roof framing, roofing materials, the attic, and the conditions that affect the roofing materials and components, including wind and hail.
Downspouts are designed to drain water from the gutters and discharge it safely away from the foundation. They often discharge directly onto the ground, but through the use of extensions or other devices, they should be configured in such a way that roof runoff does not saturate soil at or beneath the foundation.

Here, you see a foundation where erosion has washed soil away from beneath the wall, leaving the foundation unsupported in large areas. This was caused by downspouts that discharged next to the foundation. This is a very common condition and should always be called out by inspectors as a defective condition.

The unsupported part of the foundation wall bridges the area where there’s no support. If too much of the wall loses support, it may break and settle.

Downspouts should connect to the gutters securely and be free of debris. They should have some device, such as an extension or splashblock, that will carry runoff away from the foundation before discharging it to the soil.


Clogged downspouts will cause runoff to overflow the gutter.

You can see how settling caused by drainage discharged next to the foundation has cracked the brick in this 100-year-old home.

You’ll sometimes see downspouts tied into perimeter drains, and this can be a problem when the ground is frozen. Ice may prevent the system from working.

When this happens, homeowners may disconnect the downspout, which may never be re-connected.


You’ll see alternatives to conventional downspouts, such as chains. The idea is that chains are durable and runoff will simply run down the chain. How far from the foundation runoff is discharged depends on the length of the roof overhang.

Interior Downspouts 

In-roof gutters sometimes connect to downspouts installed inside the exterior walls. In older homes, these downspouts are made of metal, which eventually corrodes and leaks.

Internal downspout leakage can sometimes go unnoticed for long enough to do considerable damage.

In this Colorado home, the internal downspouts were tied to underground drains which froze, blocking drainage.  This eventually resulted in corroded downspouts, causing the framing to decay.

This condition continued for a long time.

Look at these systems carefully and use a moisture meter to check materials surrounding the internal downspouts and below internal gutters.


Learn how to master a roof inspection from beginning to end by reading the entire InterNACHI series: Mastering Roof Inspections.

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