Flashing details for roofs walls and deck connections

What is flashing and where it goes

Flashing is a purposely shaped piece of metal or a flexible membrane placed at vulnerable transitions on a building envelope. We install flashing around roof penetrations, at valleys, along chimneys and walls, under siding and around windows and doors. On decks we flash the ledger where it connects to the house and where posts or rails meet the rim to keep water out of the framing.

There are two basic kinds of detail to know. One is integrated details that sit under roofing or siding and direct water to the exterior. The other is exposed details that shed water off a visible metal surface. Both must tie into the roof and wall materials without gaps.

Why flashing matters for Pittsburgh homes

Pittsburgh and nearby communities get a mix of freeze thaw cycles, heavy rain events and seasonal wind driven storms. Those conditions force water into any weak point on a roof or wall. Missing or incorrect flashing is one of the most common causes of interior leaks, rot and accelerated material failure.

For homeowners, property managers and HOAs, good flashing preserves resale value, reduces maintenance costs and keeps living spaces dry. For new construction and additions, flashing is a code relevant detail that inspectors expect to see properly integrated with roofing, siding and window systems.

Key concepts every owner should understand

• Water moves downhill. Flashing redirects water to the exterior and away from gaps.
• Layering matters. Flashing should be layered so the outer material overlaps the piece beneath it, creating a shedding sequence.
• Materials differ. Metals and membranes behave differently when exposed to salt, movement, or incompatible materials.
• Tie in to finish materials. Flashing without a proper tie in to shingles, siding, or window flanges will fail.
• Flashing is part of the envelope. It must be coordinated with underlayment, venting and moisture management.

Common flashing types and where we use them

Here are the types you will see on residential work and the situations where they belong.

1. Step flashing. Installed where a roof meets a vertical wall. Small pieces are stepped and overlapped with the shingles.
2. Counter flashing. Used with step flashing at chimneys or masonry walls. One piece is recessed into the wall and a cap overlaps the roof side.
3. Continuous flashings. Long strips used at eaves, rakes and exposed edges to protect the roof line.
4. Kickout flashing. Installed where a roof valley meets a wall to direct water into the gutter, not behind the siding.
5. Flexible membrane flashing. Self adhered or liquid applied membranes used at irregular junctions, around skylights and at window penetrations.

Material choices compared

Inspection triggers and checklist

How we evaluate flashing without encouraging DIY repairs

We inspect flashing for proper material selection, correct sequencing with roofing and siding, secure fastenings and compatibility with adjacent materials. Our review covers roof to wall transitions, chimney counter flashing, window head details and deck ledger flashings.

We describe what needs repair, the trade coordination required and the tradeoffs between repair and replacement, so you can make an informed decision. We never expect homeowners to perform the structural or water management repairs themselves. Skilled flashing work requires access, flashing forming, and careful integration with roofing, siding and window systems.

Common questions owners ask

• Will replacing shingles fix a leak? Not always. If flashing is compromised, shingles alone will not stop water at a wall or penetration.
• Can flashing be patched? Small issues sometimes get a temporary patch, but lasting repairs usually require replacing the flashing and correcting the tie in to adjacent materials.
• Is flashing a code item? Yes. Inspectors look for correctly integrated flashing at windows, doors and roof penetrations. Local codes in Allegheny County reference standard plumbing and building code details.

Related services we coordinate

Flashing work often connects to other trades and services. We manage these interfaces so details are executed correctly. Common related services include our roof repair, siding installation, window replacement and deck building work. For larger projects we act as the general contractor to coordinate trades and inspections.

Related planning and code topics

Good flashing ties to several planning topics. We routinely link flashing details to permit requirements, moisture management and trade coordination. Read more about the permit process at our permit guidance page permit process, and about protecting wall assemblies on our moisture management page moisture management. For new construction and additions, review building code and framing topics like building codes and framing systems.

What good flashing looks like

Good flashing is continuous, layered so water sheds outward, and integrated with the adjacent materials. Fasteners do not penetrate the water path, and sealants are a secondary defense not the primary water stop. The finished flashing will sit tight to the wall or roof, without gaps, and will be compatible with nearby metals and finishes.

Helpful resources

We recommend consulting authoritative guidance when you need standards or technical references. National Roofing Contractors Association publications and the International Code Council illustrate common accepted details for roofing and flashing. For product specifics, review manufacturer instructions for the roof or window system you are using.

For our service area and examples of local projects, see locations we serve, including Pittsburgh neighborhoods and surrounding communities at our locations overview service area and locations.