Material placed over a joint and used to prevent water entry.

The area in a valley where water runs. Usually referred to with open valley configurations.

Being resistant to moisture infiltration.

The treatment of a surface or structure in order to prevent the passage of water under hydrostatic pressure.

To undergo degradation in quality and appearance which is caused by exposure to the sun, wind, rain, etc.

Small holes used to permit moisture to drain that has gathered inside a building component.

To join multiple metal or PVC components together by heat fusion.

Air temperature in ° F as measured by a thermometer with a bulb covered by a damp wick.

The thickness of an uncured material such as a coating.

To convey liquid by capillary action.

A clip that slips over the ends of tile, slate and other steep slope roofing materials in order to help prevent wind uplift damage.

The force that wind puts on structures.

(1) The upward displacement of a section of a roof system or component caused by movement of air from a location of higher air pressure, such as inside a building, to an area of lower air pressure, such as the surface of a roof during a windy day. Strong wind across the surface of a roof, especially at corners and along perimeters, creates low air pressure above the surface of the roof. Nature will automatically try to compensate for this by moving air from an area of higher pressure such as inside a building. If all penetrations and perimeters are not properly sealed, then "blow-off" can occur. (2) Displacement or blow-off of shingles or other roofing caused by the wind.

Facing into the wind.

A system for attaching heavy steep slope roofing materials such as slate r tile by using wire fasteners in addition to or in place of nails.