If you've ever had a roof leak, there's a better-than-even chance the flashing was the culprit, not the shingles. Flashing is the metal armor installed at every vulnerable junction on your roof: where the roof meets a wall, where two slopes converge in a valley, around every pipe and vent that penetrates the roof, and along every edge. In Florida's climate of extreme UV, thermal cycling, driving rain, and salt air, flashing takes a beating that most homeowners never see until water shows up on their ceiling.
Types of Roof Flashing
Drip Edge
Drip edge is the L-shaped or T-shaped metal strip installed along every roof edge (eaves and rakes). It directs water away from the fascia board and into the gutter. Florida Building Code requires drip edge on all new roof installations. Types:
- Type C (L-shaped): Basic profile. Minimum code requirement in many jurisdictions. $1-2/linear foot.
- Type D (T-shaped): Extended lower leg directs water further from fascia. Better performance. $1.50-2.50/lf. Our standard recommendation.
- Type F (Gutter apron): Extended profile designed to work with specific gutter systems. $2-3/lf.
Critical installation detail: At eaves, drip edge goes UNDER the underlayment. At rakes, it goes OVER the underlayment. This ensures water that gets under shingles is directed onto the drip edge, not behind it.
Step Flashing
Step flashing consists of individual L-shaped metal pieces woven into each course of shingles where the roof meets a vertical wall (dormers, second-story walls, additions). Each piece overlaps the one below by at least 2 inches, creating a shingle-like water shedding pattern along the wall.
Step flashing fails when: the sealant between flashing and wall cracks (FL UV destroys sealants in 5-8 years), the bottom leg rusts (galvanized steel in coastal areas), or the counter flashing above separates from the wall.
Counter Flashing
Counter flashing covers the top edge of step flashing or base flashing, typically embedded into masonry mortar joints (chimneys, stone walls) or sealed under siding. It prevents water from running behind the step flashing. In Florida, counter flashing at chimneys is the most common leak point because the mortar joint deteriorates from thermal cycling.
Valley Flashing
Valleys, where two roof slopes meet and form a channel, handle massive water volume during Florida thunderstorms. Valley treatment methods:
| Method | Cost | Performance | Recommendation |
|---|---|---|---|
| Open valley (metal) | $8-15/lf | Best for heavy rain | Best for FL |
| Closed valley (woven) | $5-8/lf | Good, aesthetic | Acceptable for FL |
| California valley (closed cut) | $6-10/lf | Good, cleaner look | Acceptable for FL |
For Pinellas County, we recommend open metal valleys. Florida's afternoon thunderstorms dump inches of rain in minutes. Open valleys handle this volume better than closed methods because the metal channel provides an unobstructed path for water flow. The W-shaped center crimp prevents water from overshooting the valley in heavy rain.
Pipe Boot (Vent) Flashing
Every plumbing vent, exhaust pipe, and HVAC penetration through the roof gets a "pipe boot," a rubber or lead collar that seals around the pipe. These are the most common failure point on any Florida roof:
- Rubber (neoprene) boots: Cheapest ($5-15 each). Last 8-12 years in FL sun before cracking. By far the most common failure.
- Lead boots: More durable ($15-30 each). Last 20+ years. Can be formed to any pipe size. Our recommendation for FL.
- Plastic boots: Budget option ($3-10). Crack within 5-7 years in FL UV. Not recommended.
- Metal + rubber hybrid: Aluminum base with replaceable rubber collar ($20-40). Best long-term option.
If your Pinellas County roof is 8-12 years old and you haven't had the pipe boots checked, there's a high probability at least one is cracked. A $150-400 boot replacement now prevents a $2,000-5,000 water damage repair later.
Chimney Flashing
Chimneys require the most complex flashing assembly: base flashing on all four sides, step flashing up the sides, counter flashing embedded in mortar joints, and a cricket (small ridge structure) on the upslope side to divert water around the chimney.
In Florida, chimney flashing fails primarily because the mortar joints where counter flashing is embedded crack from thermal cycling. When the sealant in these joints fails, water runs behind the flashing and into the roof structure. Chimney flashing replacement costs $500-1,500 and should include repointing the mortar joints where the counter flashing is set.
Flashing Materials for Florida
| Material | Cost | Lifespan (FL) | Coastal Safe | Best For |
|---|---|---|---|---|
| Aluminum | $ | 30-50 years | Yes | Standard FL choice |
| Copper | $$$$ | 70-100 years | Yes | Premium, patina aesthetic |
| Galvanized Steel | $$ | 15-25 years | No | Inland only |
| Stainless Steel | $$$ | 50-75 years | Yes | Commercial, high-end |
| Lead | $$ | 50+ years | Yes | Pipe boots, custom forming |
For Pinellas County, aluminum is the standard. It doesn't corrode in salt air, is lightweight, easy to form, and costs less than copper or stainless. The only scenario where aluminum falls short is contact with dissimilar metals (galvanic corrosion). Never install aluminum flashing in direct contact with copper or steel. Use a dielectric barrier or match all metals.
Flashing and Your Roof Replacement
During any roof replacement, ALL flashing should be replaced. This is standard practice and should be included in your quote. Reusing old flashing under new roofing material is a red flag. The flashing has the same age and wear as the shingles being removed. Even if it looks okay, the sealants are degraded and the material has been stress-cycled for 20+ years.
Exception: copper flashing in good condition can be reused since it outlasts multiple roof installations.
Signs of Flashing Failure
- Water stains near walls or chimneys: Interior stains near where the roof meets a wall almost always indicate step/counter flashing failure.
- Rust streaks on the roof: Visible rust running down from a flashing location means the metal is corroding through.
- Separated or lifted flashing edges: Visible gaps between flashing and the surface it's sealing to.
- Cracked pipe boot collars: Visible cracks in the rubber around plumbing vents (check with binoculars from the ground).
- Missing sealant: Dried, cracked, or absent sealant at flashing joints. FL sun destroys sealant in 5-8 years.
Get a Flashing Inspection
Our free roof inspection includes detailed evaluation of all flashing components. We check every pipe boot, wall transition, valley, chimney, and edge for signs of failure. Available throughout St. Petersburg,Clearwater, and all of Pinellas County.