In the construction industry, “flashing” refers to thin pieces of impervious material installed to prevent the passage of water into a structure from a joint, through a wall, or around projections. Flashing is a crucial component in waterproofing and weatherproofing, protecting buildings from water damage, which can lead to structural issues and mold growth.
Composition and Structure
Flashings are commonly made from materials such as aluminum, copper, stainless steel, or lead, although modern alternatives include rubber, PVC, or bituminous materials. The choice of material depends on factors such as the building’s location, climate, and the specific area where the flashing will be installed. They come in various forms, including strips, sheets, tapes, and prefabricated units, designed to fit specific areas and needs.
Functionality
The primary function of flashing is to direct water away from critical areas of a building, preventing leaks and water damage. Flashing is installed at vulnerable points, such as:
- Roof valleys
- Chimneys
- Skylights
- Windows and doors
- Vent pipes
- Wall penetrations
Correctly installed flashing forms a barrier against moisture, preventing water from seeping into the building’s structure. Flashing is often installed overlapping in such a way that water is directed away from the structure and toward the ground or gutter system.
Types of Flashing
There are several types of flashing commonly used in construction:
- Step Flashing: Step flashing is commonly used where a sloped roof intersects with a vertical wall. It is installed in small “steps” and integrated with shingles or other roofing material.
- Drip Edge: Drip edge flashing is installed at the edges of a roof to direct water away from the fascia and into the gutter system.
- Counterflashing: Counterflashing is installed to overlap and cover the top edge of vertical base flashing, such as that installed around a chimney.
- Cap Flashing: Cap flashing is used to protect the tops of parapet walls or where a sloped roof meets a vertical wall.
- Window and Door Flashing: Flashing installed around windows and doors to prevent water from penetrating the building envelope.
Installation and Maintenance
Proper installation and maintenance of flashing are critical for its effectiveness. Some essential guidelines include:
- Ensuring that flashing materials are compatible with the surrounding building materials.
- Correctly positioning flashing to direct water away from the building.
- Using sealants and adhesives as needed to secure flashing in place.
- Regularly inspecting and maintaining flashing to ensure its integrity and effectiveness.
Conclusion
Flashing is a vital component in protecting buildings from water damage. By correctly installing flashing at vulnerable points, such as roof joints, windows, and doors, construction professionals can ensure the longevity and integrity of a building’s structure.
