Roof flashing is thin sheets of metal - typically aluminum, galvanized steel, or copper - installed at joints, transitions, and penetrations in the roofing system. Flashing directs water away from vulnerable areas and is one of the most critical components for preventing leaks.
Why Flashing Is Critical
Every roof has areas where different surfaces meet or where items penetrate through the roofing material. These transitions are natural weak points where water can enter. Flashing creates a watertight seal at these junctions, protecting your home from moisture intrusion.
In New England's harsh climate, where heavy rain, snow, ice, and freeze-thaw cycles are common, properly installed and maintained flashing is essential. Most roof leaks in Massachusetts and Rhode Island homes can be traced back to failed or improperly installed flashing.
Types of Roof Flashing
Step Flashing
Step flashing consists of small L-shaped metal pieces installed in a overlapping "step" pattern along the intersection of a sloped roof and a vertical wall (such as where a roof meets a dormer or an addition). Each piece of step flashing overlaps the one below it and is integrated with the shingle course at that level.
**Used at:** Wall-to-roof transitions, dormers, additions
Valley Flashing
Installed in the "valley" formed where two roof slopes meet. Open valleys use exposed metal flashing; closed valleys use overlapping shingles with concealed flashing underneath. In Massachusetts and Rhode Island, open metal valleys are preferred for their superior water-shedding performance in heavy rain and snowmelt.
**Used at:** Where two roof planes meet
Chimney Flashing
Chimney flashing is a multi-component system:
- •**Base flashing** - Runs up the sides of the chimney from the roof
- •**Counter flashing** - Embedded into the chimney masonry and overlaps the base flashing
- •**Saddle (cricket)** - A peaked structure behind wide chimneys to deflect water
**Used at:** Chimney-roof intersections
Pipe Boot / Vent Flashing
A pre-formed flashing piece, often with a rubber collar, that seals around plumbing vents, exhaust vents, and other pipe penetrations through the roof.
**Used at:** All pipe and vent penetrations
Drip Edge Flashing
Metal flashing installed along the eaves and rakes of the roof to direct water into gutters and away from the fascia. See also: [Drip Edge](/glossary/drip-edge/)
**Used at:** Roof edges
Skylight Flashing
Manufactured flashing kits, often integrated with the skylight unit itself, that seal the skylight curb to the surrounding roofing material.
**Used at:** Skylight installations
Common Flashing Materials
| Material | Lifespan | Best For | Notes |
|---|---|---|---|
| Galvanized Steel | 20-30 years | Most residential applications | Most common, cost-effective |
| Aluminum | 20-30 years | Valleys, pipe boots | Lightweight, easy to work |
| Copper | 70+ years | Premium installations | Excellent durability, higher cost |
| Lead | 50+ years | Complex shapes | Easy to form, less common today |
Signs of Flashing Failure
- •Water stains on ceilings near chimneys, walls, or skylights
- •Visible rust, corrosion, or gaps in metal flashing
- •Lifted or separated flashing at chimney base
- •Cracked or missing caulk at flashing joints
- •Daylight visible through flashing joints during attic inspection
Flashing and New England Homes
Many Massachusetts and Rhode Island homes have chimney flashing that was sealed with tar or caulk rather than properly integrated step and counter flashing. This is a common source of leaks, especially in older homes. Tar-based patches typically fail within a few years and require repeated patching - a permanent fix involves removing the roofing material and reinstalling proper mechanically fastened flashing.
Professional Flashing Services from Roofing Doctors
Roofing Doctors provides comprehensive flashing inspection, repair, and replacement services across Massachusetts and Rhode Island. Our certified crews specialize in both modern installations and historic New England homes where complex rooflines require custom fabricated flashing solutions.