If you own a Massachusetts house built before 2010, walk outside and look at every spot where a roof eave dies into a sidewall. If there is no small L-shaped metal piece kicking water out into the gutter, you have a code violation and, more likely, a slow leak that has been eating your sheathing for years. That missing piece is called a kick-out flashing, and it is the single most commonly skipped detail in Massachusetts residential construction.

Home inspectors flag it on almost every pre-2010 house they see. Siding crews still cover over the same defect on re-side jobs today. And when the rot finally shows up, homeowners insurance almost always denies the claim as gradual maintenance damage instead of a covered sudden event.

What is kick-out flashing?

Kick-out flashing is an L-shaped metal or molded plastic diverter installed at the very bottom of a roof-to-sidewall junction. Its one job is to catch water running down the roof-side edge of a wall and kick it out into the gutter, instead of letting it wash straight down the siding and behind it.

Think of a garage roof that butts into the second story of a colonial. Water sheeting down the roof surface hits the last shingle course, and without a diverter, it curls around the fascia and streams down the wall. Behind vinyl or cedar or fiber cement, that water finds house wrap seams, nail holes, and every window flange it can reach. Rot follows within a few winters.

The DOE Building Science Education office describes kick-outs as the deflector that "diverts rainwater runoff into gutters and protects walls from water intrusion." The DOE Building America Solution Center is more blunt: missing kick-outs are a documented source of "thousands of dollars worth of damage" per house.

Is kick-out flashing required by code in Massachusetts?

Yes, and it has been since the state adopted the 2009 International Residential Code. The IRC first named kick-out flashing as a requirement in the 2009 edition under R703.8. It has been carried forward in every edition since.

Here is where it sits in the codes MA actually enforces:

• 780 CMR 9th Edition (based on the 2015 I-Codes, effective October 20, 2017): sidewall flashing requirements at IRC R703.4 and R903.2.1.
• 780 CMR 10th Edition (based on the 2021 I-Codes, effective October 11, 2024, sole code as of July 1, 2025): same requirement, same section numbering in the IRC portion adopted by Chapter 51 of 780 CMR.

That means if your siding was replaced under permit any time after roughly 2011 and there is no kick-out at a roof-to-wall junction, the work was not to code. Whether a local inspector caught it is a separate question. In practice, they mostly do not. Roofers assume the siding crew will install it. Siding crews assume the roofer did. Nobody does.

What size does kick-out flashing need to be?

The IRC minimum is 4 inches high by 4 inches out along the roof, in metal at least 0.019 inches thick (26 gauge galvanized), per the DOE Building America Solution Center's summary of R703.4 and R903.2.1. That is the floor. Do not accept it as a target.

The DOE Building America Solution Center and every serious home inspector's guide recommend 6 inches, and that the roof underlayment run at least 6 inches up the sidewall behind the flashing and behind the water-resistive barrier. That extra 2 inches is what makes the difference on a windy nor'easter when water is being driven sideways up the roof.

Kick-out flashing spec, at a glance

Spec	IRC / 780 CMR minimum	DOE and inspector best practice
Height up the wall	4 in	6 in
Length out along roof	4 in	6 in
Metal thickness	0.019 in (26 ga galvanized)	Same or heavier
Fastening	Attach to roof deck	Roof deck only, never fastened to the sidewall
Underlayment lap	Continue up sidewall	6 in above roof deck, behind WRB

Prefabricated single-piece diverters cost about $15 to $30 each. Site-fabricated ones (bent from coil stock on the tailgate) work if the installer knows what they are doing, but the DOE explicitly prefers prefabricated seamless pieces because the site-bent version is easy to undersize and easy to leave with an unsealed seam.

How can you tell if yours is missing?

Look at every place a lower roof runs into a taller wall. The classic MA suspects:

• Garage roof meeting the second story of the house.
• Front porch or entry portico roof meeting the main wall.
• A dormer cheek meeting the main roof (this one needs a kick-out where the dormer sidewall eave terminates).
• Kitchen or family room bump-out with its own roof meeting the main house.
• Two-story rear addition where a shed roof meets the taller original house.

Stand under each junction. If you see:

• A vertical stripe of stained or discolored siding directly below where the roof eave meets the wall
• Peeling paint on cedar or fiber cement in that same strip
• Efflorescence or moss growth on the siding directly under the junction
• Mold or water stains on the interior wall or ceiling in the room behind that junction

then water is running down the wall, not into the gutter. On vinyl siding, look for a horizontal stain line where water has been draining sideways along a course. On cedar shingles, look for shingles that are grayer, cupped, or split in a vertical band under the junction. For more of the tell-tale symptoms of failing sidewalls, our guide on the signs of trim, soffit, and fascia rot in MA homes shows the pattern from the outside in.

Better still, when the siding comes off during a replacement, ask the crew to photograph the sheathing at every roof-wall junction. It is the number one thing that turns up during teardown, which is exactly what our guide on what MA contractors find behind old siding documents.

What does it cost to add kick-out flashing?

The honest answer is "it depends on your siding." A kick-out that gets added during a re-roof or a re-side is essentially free labor on top of a $20 part. Retrofitting on an existing wall, without disturbing the rest of the assembly, ranges wildly.

Scenario	Realistic cost range	Notes
Added during a full siding replacement	Materials only, roughly $20 per junction	No labor premium if the crew is competent
Added during a re-roof, existing siding stays	$150 to $400 per junction	Roofer lifts the bottom course of siding, slides in flashing
Retrofit on existing vinyl siding	$150 to $300 per junction	Vinyl can be unzipped and re-clipped
Retrofit on existing cedar or fiber cement	$300 to $600 per junction	Bottom courses often need to be cut and repatched, sometimes repainted
Retrofit where sheathing is already rotted	$2,000 to $10,000+	Now it's a wall repair, not a flashing job
Retrofit on stucco or masonry	Call a specialty contractor	Cutting and patching is the whole job

Those numbers are for the mechanical work only. If the rot has been going for five or ten winters, budget for sheathing, house wrap, insulation, and drywall repair on the interior side.

Retrofitting during other exterior work is by far the smartest sequencing. A $20 diverter installed while a crew is already on a ladder for a re-roof is trivial. The same $20 diverter installed on its own, months later, is a $400 service call.

Will homeowners insurance cover the wall rot?

Usually no, and this is the part most articles skip. A standard MA HO-3 policy covers sudden, accidental water damage (a pipe bursts, a tree punctures the roof in a storm). It excludes gradual damage from long-term leaks and from lack of maintenance. Missing kick-out flashing is the textbook example of the second category.

When the adjuster opens the wall and sees years of layered staining and mycelium in the sheathing, the claim will be denied as maintenance. The one narrow exception is if you can prove the damage was caused by a specific covered event (a storm blew the flashing off, for example) and you file quickly. Even then, expect a fight.

That's why the code question actually matters. If the siding was installed under permit after 780 CMR started requiring kick-outs and the contractor didn't install them, you may have recourse against the contractor under the Home Improvement Contractor law, not your insurer. For how the "sudden vs. maintenance" line gets drawn in real MA claims, see our companion piece on wind-damage siding insurance claims in MA.

What to ask your siding or roofing contractor

Whether you're getting quotes for a new roof, a re-side, or a spot repair, three specific questions separate a serious contractor from a cover-and-run outfit:

1. "Will you install kick-out flashings at every roof-to-sidewall junction, and can you show me a spec sheet or a photo of one you installed last month?" A crew that has to look this up is not the crew you want.
2. "Are you using a prefabricated diverter or site-bending one?" Prefabricated is not always required, but if they are site-bending, ask them to describe how they'll seal the seam. If they say "caulk," walk.
3. "How far up the sidewall will the roof underlayment run?" The right answer is 6 inches minimum, tucked behind the water-resistive barrier so any water that gets past the flashing still has a path to daylight.

Kick-out flashing is a specific and narrow detail, but it lives inside a bigger drainage-plane conversation. If your house doesn't have a rainscreen or proper WRB behind the siding, a good kick-out only postpones the problem. Our guide on house wrap and rain screen systems for MA siding covers the assembly the flashing is supposed to be part of.

FAQ

Do I have to install kick-out flashing if I'm just doing a spot siding repair? No, but the inspector who signs off on the next work you pull a permit for will likely flag it. And if you know it's missing and don't add it, you own the leak. Massachusetts case law is not kind to homeowners who ignore known defects during a sale.

My house was built in 1985. Am I grandfathered in? For the original construction, yes, the 2009 code doesn't reach backward. For any siding, roofing, or wall work done under a permit since 2011 or so, no. New work has to meet current code, and current code requires the flashing at every applicable junction.

Can I install a kick-out myself? On existing vinyl, some homeowners do. The correct sequence (unzip the bottom course, lift the housewrap tab, slide the diverter over the last piece of step flashing, re-lap the housewrap, re-zip the vinyl) is fiddly but doable. On cedar, fiber cement, or stucco, hire it out. The cost of getting the flashing wrong is a wall.

Is kick-out flashing needed at every roof-wall junction, or only some? Every junction where a sloped roof eave terminates against a vertical wall. Rakes (the sloped edge of the roof running up the gable) do not need one. It is specifically the bottom of the eave, where water is being shed sideways.

Will a home inspector always catch a missing kick-out on a MA home sale? A competent one will. It is one of the most commonly cited defects on inspection reports statewide. If you're buying a MA house with any roof-to-wall junction and the report doesn't mention kick-outs, ask your inspector directly.

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