By Kenton Shepard

ROOF CONSIDERATIONS

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 sol to bear the weight of the building structure.

Roof Flashing

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

Vents

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

Drip Edge

Drip edge is a flashing installed along the sloped edges of a roof to protect roof sheathing from moisture. Levels areas of the roof, such along the bottom of a sloped area, are usually protected by the overhang of the roof-covering material.

Roof to Wall Junctions

Step flashing should be used with roofing materials installed in courses such as tiles and shingles.

Chimneys

Chimneys, especially masonry chimneys can be extremely difficult to flash correctly and often require cutting a slot into the chimney to accept counter flashing.

Skylights

Home-made skylight flashing is relatively commend and ineffective

Pitched (sloped) Roof

Roofs with a steeper slope will shed water more quickly than flat or low-slope roofs. In most cases this will lessen 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.

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.

Type of Roof Covering Materials

Different types of roof-covering materials have different lifespans. Among the roof-covering materials with long lifespans (all things being equal) are...

• slate
• tile
• metal

The lifespans of roof-covering materials are affected by the following:

• Material quality
• Installation method and quality
• Number of existing layers (less is better)
• Roof orientation (South-facing roofs deteriorate more quickly)
• roof pitch (amount of slope)
• Climate (snow, rain, ice, hail, etc.)
• Building site (overhanging branches, protection from wind, etc.
• shingle color (dark colors absorb more heat)
• Elevation (deterioration from ultra violet light)
• Roof structure ventilation (cooled roofs last longer)
• Quality of maintenance