Roof Leaks Around Dormers and Walls: Step Flashing Explained
Some of the worst roof leaks in Murfreesboro are not on the roof at all. They are in the wall below it: a stain at the top of a window on the first floor, siding that is soft at the bottom of a two-story section, a corner of drywall in the garage that keeps bubbling. Every one traces up to the line where a roof slope runs into a vertical wall, and to a piece of bent metal that was either missing, too short, or installed in the wrong order.
What step flashing is
Where a roof slope meets a wall — the side of a dormer, the wall of a two-story section rising above a one-story roof, the side of a chimney — water running down the wall and water running down the roof meet. Step flashing is a series of L-shaped metal pieces, one per shingle course, each lapped over the shingle below and under the shingle above, with the vertical leg running up the wall behind the siding. Water that hits the wall runs down the vertical leg, onto the horizontal leg, and out onto the shingle below. Each piece steps down the roof; that is the name.
Done right, it is close to permanent. Done wrong, it leaks from the first storm, but slowly enough that nobody notices for years.
How it goes wrong on Murfreesboro houses
Most of the city was built between 2005 and 2020 by production crews working fast, and the wall-to-roof junctions are where the speed shows.
Short flashing. Pieces cut too short up the wall, so wind-driven rain gets over the top. Common where a crew ran out of stock and made do.
Continuous flashing instead of step. One long strip of metal caulked along the joint instead of individual stepped pieces. The caulk fails in three summers of Tennessee heat and the strip becomes a gutter aimed into the wall.
No kick-out. At the bottom of the run, where the roof edge meets the wall, a kick-out flashing is supposed to turn the water out into the gutter. Without it, every drop that came down that wall goes behind the siding at the corner. On a two-story house in Blackman or Salem with a one-story garage roof running into the main wall, the missing kick-out shows up as rot at the bottom corner of the wall, usually right where the gutter ends.
Housewrap lapped wrong. The housewrap should lap over the top of the vertical flashing leg so water on the wrap runs out onto the flashing. When the flashing goes on after the wrap, water on the wrap runs behind the flashing. On new builds this is common.
Dormers on the newer farmhouse builds. The 2016–2022 houses south of the city with two or three dormers on the front slope have six wall junctions each, and every one is a chance to get it wrong.
How to spot it from inside
- A stain on the ceiling or the top of a wall directly below where a higher roof section meets the wall
- A stain at the top of a window on a lower floor, under a dormer or a roof-to-wall line
- Siding that is soft, discolored or pulling away at the bottom corner of a two-story wall
- In the attic of a one-story section, a dark line on the framing along the wall it butts into
The leak is often several feet from the stain because the water runs down the inside of the wall before it finds drywall. Our post on tracing a leak from inside covers the attic side.
What the repair involves
A real fix means taking off the siding along the junction and the shingles in the first few courses, then rebuilding it in the right order: underlayment or membrane up the wall, step flashing woven course by course, a kick-out at the bottom, housewrap lapped over the flashing, and siding reinstalled. Caulk is not a repair here; it is a delay.
| Job | Typical Murfreesboro price |
|---|---|
| Step flashing, one wall junction, 8–15 ft | $450 – $1,100 |
| Add a kick-out flashing at one corner | $150 – $350 |
| Dormer, both sides and the front | $700 – $1,600 |
| Chimney step and counter-flashing | $600 – $1,500 |
| Replace rotted sheathing behind the wall | $90 – $150 per sheet, plus siding |
Vinyl siding comes off and goes back easily. Brick is a different job: the flashing has to be counter-flashed into a mortar joint, and the price goes toward the top of each range.
Why builders skipped it
Step flashing takes time, kick-outs are an extra part, and neither is inspected closely on a production build. Tennessee adopted the International Residential Code, which requires flashing at every roof-to-wall intersection, but "flashing" on a fast build often meant one strip and a tube of caulk. The result is a whole generation of houses in Rutherford County where the roof itself is sound and the walls under it are quietly getting wet.
Checking your own house
Walk around the outside and find every place a roof runs into a wall. On a typical Blackman two-story there are three to six. At each one:
- Look at the bottom corner, where the roof edge meets the wall. Is there a small angled piece of metal turning water into the gutter? That is the kick-out. If there is none, note it.
- Look at the siding just below and beside that corner for stains, swelling or soft spots. Press gently on it.
- Look up the joint for caulk. A thick bead where the shingles meet the siding often means flashing was skipped or cut short.
- Inside, check the drywall and window trim below each junction.
Take a photo at each spot. If two or more look suspect, that is worth a contractor's visit before the next storm season.
Questions to ask about a flashing repair
- Will you remove the siding so the flashing goes behind it, or only work from the roof side?
- Will each piece be a separate step flashing, woven with the shingles?
- Will you add a kick-out at the bottom?
- How will the housewrap be lapped over the new flashing?
- What will you do if the sheathing behind the siding is soft?
- On brick, will the counter-flashing be set into a cut mortar joint?
If the answer to the first question is "no, we can seal it from the roof," get a second opinion. Step flashing leaks are fixed behind the siding, not on top of it.
Common mistakes
- Re-caulking every year. It keeps the stain away for a season and lets the rot behind it continue.
- Replacing the siding without the flashing. New siding over the same flashing gives you the same leak.
- Fixing one side of a dormer. If one side was done wrong, the other probably was too.
- Waiting for a stain inside. By then the sheathing has usually been wet for a while.
Getting it checked
If your house has a two-story section over a one-story roof, a dormer, or a chimney, and it was built after 2005, the junctions are worth a look before a leak shows up inside. A good roof inspection covers every one of them, and a fix now is a $450–$1,100 repair instead of a wall rebuild in three years.
Common questions
How long does a step flashing repair take?
A single wall junction is usually a day, including taking off and putting back the siding. A dormer may take a day or two, and brick work takes longer.
Can a flashing leak cause mold?
Yes. Water that runs behind siding for months keeps the sheathing and framing damp, which is where mold grows. That is a good reason to fix these early.
Do I need a roofer or a siding contractor?
Usually a roofer who is comfortable removing and reinstalling siding. On some jobs a roofer and a siding contractor work together. Ask who is responsible for the whole junction, top to bottom.
Need roof work in Murfreesboro?
Call for a free estimate. Mon–Sat 7am–7pm.