Mastering Roof Inspections: Roof Drainage Systems, Part 1

by Kenton Shepard and Nick Gromicko, CMI®

GUTTERS 

If runoff from the roof is allowed to discharge next to the home's foundation, serious structural problems can develop. Saturated soil can lose its ability to support the weight of the home, or seepage can undermine the foundation.

The most common roof-drainage control system in residential construction is gutters hung from the roof edge attached to downspouts.

The gutter problems you find may be related to the materials from which the gutters are made,  the quality of installation, the environmental conditions, or some combination of all three.

Gutter Materials

Vinyl gutters are fragile, and you may find them broken or disconnected.

Galvanized steel gutters are common, and you’ll see them all over North America. If they’re painted, it may be difficult to tell steel gutters  from aluminum just by looking, but you should be able to tell the difference by tapping them with your finger.

Copper gutters generally last a long time compared to steel and vinyl.

Installation 

Problems with installation range from improperly sloped gutters to gutters that are loose or poorly attached. You may be able to identify improper slope by observing standing water in the gutter or the accumulation of sediment in portions of the gutter away from the downspouts.

You can check the slope from the ground by looking at the margins between the gutter and roof or the gutter and fascia.

Metal gutters are subject to corrosion, especially if debris has been allowed to accumulate. Debris holds moisture next to the metal, so watch for corrosion in gutters which have tree branches hanging over them. You may find advanced corrosion by probing. Corrosion often starts at seams.

On homes with steeper roofs, gutters may need to be installed using standoffs to help ensure that runoff doesn’t overshoot the gutter.

In areas with snowfall, it’s not unusual to find gutters bent from sliding snow, especially on homes with metal roofs.

Built-In Gutters

The other type is built into the edge of the roof and is more common.

Roofs with this second type of gutter are easy to spot because the roof slope will not extend clear to the edge of the roof.

Do not probe these gutters. If you puncture the gutter, you may be responsible for damage caused by leakage. Look for signs of leakage in the soffit below the gutter.