Most roof leaks don’t start in the middle of the roof. They start where the roof meets something else: a skylight, a chimney, a wall, a vent pipe, a valley. The metal that seals those joints is called flashing, and when it’s worn, missing or installed wrong, water gets in no matter how good the shingles or tiles are. HomeGuard Roofing repairs and rebuilds flashing on Dublin homes of every age and roof type.
Call (925) 644-8514 or call to schedule a flashing inspection.
Flashing is formed metal, usually galvanized steel, aluminum or copper, plus rubber boots on pipes. It’s layered so water always runs over the top of the next piece and away from the joint. Done right, it doesn’t depend on caulk at all. Done wrong, or with the layers reversed, it funnels water straight into the house.
| Flashing | Where it goes | What fails |
|---|---|---|
| Step flashing | Along a wall that runs up the slope of the roof, one piece per course of shingles or tile | Rusted pieces, missing pieces, stucco or siding installed tight against it |
| Headwall (apron) flashing | Where the top of a roof slope meets a wall | Pulled loose, short laps |
| Kickout flashing | At the bottom of a roof-to-wall joint, turning water into the gutter | Missing on many older homes; water runs behind the wall |
| Counter-flashing | Covers the top of step flashing on chimneys and some walls | Mortar joints cracked, metal pulled loose |
| Chimney cricket | A small peaked “saddle” behind wider chimneys to split the water | Missing, or rusted through |
| Valley metal | Down the valleys where two slopes meet | Rust, debris dams, worn underlayment beneath |
| Pipe boots and vent flashing | Plumbing vents, bath fans, furnace B-vents | UV-cracked rubber, loose storm collars |
| Drip edge | Along the roof edges | Missing, letting water wick back into the fascia |
| Skylight curb flashing | Around skylights | Mastic-only seals, wrong kit for the roof type |
Dublin’s older homes, especially 1960s–80s West Dublin ranches, often have original skylights, some of them plastic domes. Newer homes usually have glass units on curbs or mounted to the deck.
There are three common causes, each with a different fix:
If it drips on cold, dry mornings, suspect condensation. If it drips only when it rains, suspect the flashing or the unit.
If the skylight is old, cracked, yellowed or crazed, re-flashing it alone doesn’t make sense. You’d pay for the labor and still have a failing unit. Replacing the skylight and its flashing together is usually better value. If the unit is in good shape, we re-flash it with a flashing kit matched to the skylight and the roof type: shingle, tile or flat.
Masonry chimneys are flashed in two layers: step flashing tied into the roofing, and counter-flashing set into the mortar joints and lapped over it. When mortar cracks or the counter-flashing pulls out, water gets behind the step flashing and runs down the chimney into the attic or a wall.
Wider chimneys also need a cricket on the uphill side, so water doesn’t pool behind them. Building codes generally require one on chimneys more than 30 inches wide. Many older chimneys have no cricket, or a rusted one.
Metal flues (the round pipes from furnaces, water heaters and some fireplaces) are sealed with a flashing plate and a storm collar. Loose or rusted collars are a common winter leak source.
Both, often. Water can also enter through cracked brick, the chimney crown on top, or a missing chimney cap. We check the roof flashing first, and if the masonry itself is the problem, we’ll tell you so you can call a mason or chimney specialist.
Many Dublin homes have stucco walls rising above lower roofs: two-story homes over a garage or family room, and split-levels in West Dublin. Those joints rely on step flashing, a headwall flashing and a kickout at the bottom. Current code calls for kickout flashing where a roof edge meets a wall, but many older homes were built without it. The result is water running behind the stucco, rotting the framing and showing up inside as a “roof leak.”
Repairing these joints properly usually means opening the roofing along the wall, replacing the flashing and adding a kickout, then patching the stucco edge.
Valleys carry water from two roof slopes at once, so they get twice the water and most of the debris. Leaves and needles dam them up, pushing water sideways under the roofing. We clear valleys, replace rusted valley metal and rebuild the underlayment under it. On tile roofs, valley work often goes hand in hand with tile roof repair.
Caulk is a short-term patch. Dublin’s summer heat dries it out and it pulls away, often within a year or two. If the flashing itself is rusted, missing or installed in the wrong order, caulk can’t fix it.
| Job | Typical range |
|---|---|
| Pipe boot or vent flashing replacement | Range TBD |
| Skylight re-flash | Range TBD |
| Skylight replacement with new flashing | Range TBD |
| Chimney re-flash (step and counter-flashing) | Range TBD |
| Chimney cricket | Range TBD |
| Wall flashing rebuild with kickout | Range TBD |
| Valley rebuild | Range TBD |
Price depends on roof type (tile adds labor), the size of the joint, framing damage, stucco or siding work, and access.
What the homeowner saw: Drips from two plastic dome skylights during storms.
What we usually find: Brittle, crazed domes and mastic-sealed curbs.
The fix: New skylights with factory flashing kits, the curbs rebuilt, and the shingles around them relaid.
What the homeowner saw: A stain on the wall next to the fireplace, only during storms.
What we usually find: Counter-flashing pulled out of cracked mortar joints and no cricket behind a wide chimney.
The fix: New step and counter-flashing, a cricket built on the uphill side, and a note to the homeowner about cracks in the chimney crown for a mason to address.
Nicole F.Dublin Hills · Chimney flashing rebuild“Leak around our chimney that two handymen ‘fixed’ with caulk. These guys rebuilt the step flashing properly. Three storms later, not a drop.”
Formed metal or rubber pieces that seal the joints where the roof meets walls, chimneys, skylights, vents and valleys. They’re layered so water runs away from the joint.
That’s usually condensation, not a roof leak. Warm, humid indoor air condenses on the cold skylight. Better ventilation or a newer insulated skylight usually solves it.
Not always. If the skylight is in good condition, re-flashing it is enough. If it’s old, cracked or cloudy, replacing it with its flashing together is better value.
A bent piece of flashing at the bottom edge of a roof-to-wall joint that turns water into the gutter instead of letting it run behind the wall. Many older homes don’t have one.
A small peaked structure on the uphill side of a chimney that splits water around it. Wider chimneys generally need one.
If the problem is the flashing, yes. If the brick, mortar or chimney crown is cracked, we’ll fix the roof side and recommend a mason for the masonry.
If your leak is near a skylight, chimney, wall or vent, the flashing is the first place to look. Call HomeGuard Roofing at (925) 644-8514 or call to schedule a flashing inspection.
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