Roof Defects

By Kenton Shepard

ROOFS- State by State Codes, Rebates and Energy Programs

Search anywhere in the U.S to find out what codes & standards, voluntary energy programs and rebate programs concerning roofs are in effect.

COMMON ROOF DEFECTS

With so many different types of roofing systems in place, we will try to cover typical problems.

Roof Drainage Systems

Gutters and downspouts which drain roof runoff away from the home are an important part of protecting the foundation.  Moisture is the primary cause of foundation problems because it affects the ability of the soil to bear the weight of the building structure.

• Gutters
  • debris-filled
  • Improper slope
  • poor connection
  • corrosion or leakage
  • missing components (end caps)
  • missing or only partially installed gutters
  • tie to perimeter drain
• Downspouts
  • Extensions required to route roof drainage further from foundation.
  • tie to perimeter drains. Downspouts which tie to perimeter drains route roof runoff directly to the foundation. If the system should be overwhelmed, fail to operate correctly or defvelop a leak, this runoff may enter the soil beneath the foundation. While not technically a defect, it's not a good practice.

Pitched (sloped) Roof

Roofs with a steeper slope will shed water more quickly than flat or low-slope roofs. In most cases this will reduce the chances for leakage. The exception is situations in which water running down one roof may run up under the shingles of an opposing roof, such as at valleys.

Inspectors should note locations where snow sliding off roofs will accumulate, especially in homes with metal roofs. Snow sliding off metal roofs can cause considerable damage or injury/death.

Low slope Roofs

Low slope and flat roofs sometimes allow water to pool. Pooled water will stand until it evaporates, giving moisture more time in which to find an avenue through or around the roof-covering material and underlying membrane. Low-slope pitches may have special installation requirements or limitations in some areas.

ROOF FLASHINGS

To avoid moisture intrusion of the wall or roof, it's important that flashing is present and properly installed in the following areas:

Vent Flashing

Roofing should extend over the uphill portion of flashing, but on the down hill side flashing should extend out over the roof-covering material.

The vent on the left is flashed correctly. Vents depending on caulk or mastic for weatherproofing will eventually leak as the sealant dries and cracks. Recommend annual maintenance.

A good reason to keep vents well away from valleys. This vent will crack at its base, causing leaks.

Drip Edge

Drip edge is a flashing installed along the edges of a roof to protect roof sheathing from moisture. While missing edge flashing isnot necessarily a defect, installing it is good building practice.

Edge metal, also called drip edge, protects roof sheathing.

Roof to Wall Junction Flashing

Areas where roof and walls meet require special flashing details. Roof-covering materials installed in courses, such as asphalt shingles, require lapped step-flashing and counter-flashing.

Two poor installations. Left, the counter-flashing is caulked to the stucco. Over time, caulk will dry, shrink, crack and leak unless dilligently maintained. Log homes are notorious for poor counter-flashing practices in this area. Proper installation requires slotting logs.

Kick-out flashing

In areas at which walls extend past roofs, kick-out flashing must be correctly installed. An example of missing kickout flashing...

                                                   Water runs down the roof...                                                   ...and into the hole!

After it enters the hole, roof runoff can enter the wall assembly where it may or may not be apparent. In this particular situation, the tennants below had no idea there was a problem. Drywall gave no indication... no dark stains. Possible mold problems.

Kickout flashing installed correctly

Chimney Flashing

Chimneys, especially stone or masonry chimneys, are often poorly flashed. Counter-flashing should be installed behind stucco, wood and composite siding.

Installed correctly, counter-flashing on brick chimneys should be inserted into mortar joints as on the left. Counterflashing caulked into place will require more maintenance to prevent leakage.

Wrong- but very common. Stone should terminate several inches above the roof and counter-flashing should run up behind the stone.

Skylight Flashing

Skylights require good flashing practices...

Properly flashed skylight

DEFECTIVE SHINGLES

Defective shingles show failure in a number of ways. Here are a couple...

                                         Hail damage or blistering?                                 Hairline cracking:defective shingles or poor storage pracitices?

Don't be too quick to make a call. Inspectors are not required to identify sources of damage!

All photos by Kenton Shepard

Sources for More Information

Roof Defect Identification- Home Inspection and Construction Information Web Site.