Diagnosing and fixing a chimney problem at an Everett address

CSIA lists three signs of chimney water intrusion a homeowner can see without a ladder: rust stains, dripping or standing water, and bent or damaged flashing. Two of those three are describing metal, and that is the useful clue at an Everett address.

A large share of the city's housing sits within a mile of tidewater. Guidance on coastal exposure holds that standard corrosivity categories are not sufficient inside that mile, because the microenvironment decides — prevailing wind direction, how exposed the face is, how close the salt spray gets. On the same structure, faces sheltered from the constant salt wind kept far more of their protective coating than the faces taking it directly.

So rust running down a brick face is not a brick problem. It is a report from something above: a cap or chase cover perforating, a storm collar opening up, fasteners failing, or a flashing edge thinning. Repointing under that, or sealing over it, treats the stain and leaves the source running.

The reason it turns into damage rather than just staining is drying time. Brick and mortar are networks of microscopic capillaries that pull water in by suction and then dry themselves by evaporation, and a leak starts when the masonry stops fully drying between wettings. Everett's rain is concentrated rather than constant — 6.14 inches in November, 5.25 in December, and 4.08 in January against 0.95 in July — so for a stretch of months the drying interval simply closes.

Flashing is the detail people most often assume is roofing work. It is worth separating, because in Everett the assumption has a permit consequence attached to it.

Three zones, not one

A chimney has three distinct flashing zones. The roof intersection is only one of them — the chimney base and the area under the crown need flashing too, and a leak diagnosed only at the roof line misses two thirds of the system.

Three parts at the roof line

Correct roof-to-chimney flashing is base flashing, counter flashing, and through-wall flashing working together, and on a sloped roof the base flashing has to be stepped rather than run as a single piece.

Counter flashing belongs in the masonry

It is meant to be let into a mortar joint three quarters of an inch to an inch deep and mortared solidly in, not surface-glued to the face of the brick. That is masonry work performed on a roof, which is why it sits awkwardly between two trades.

It is an expansion joint

Flashing exists because masonry and roofing move at different rates. A rigid caulk bead or tar smear over the gap cannot follow that movement, so it fails — usually within a season or two — and it is the most common thing found holding an Everett flashing together.

Now the paperwork. Everett splits the residential building permit into subtypes with their own submittal checklists. Structural work on an existing house is filed as a residential alteration. Re-roofing is a separate subtype covering replacement of existing roofing material only. They are not one application, so a roof replacement and chimney work above the roof line are two decisions that need sequencing rather than one line item on a roofer's quote.

1. 1

   Diagnose before the roofer is booked

   If the masonry the counter flashing has to be cut into is failing, the flashing cannot be detailed correctly over it. That is a reason to look at the chimney first, not after the shingles are down.

2. 2

   Make the masonry sound

   Crown, cap, and the joints the counter flashing will be let into. This is chimney work in a different permit subtype from the roofing, and it wants dry weather.

3. 3

   Detail the flashing with the roof open

   Base, counter, and through-wall flashing go in while the roofing is off and the chimney is accessible from every side. Doing it later means lifting new roofing to do it properly.

4. 4

   Confirm the cricket question

   A cricket — a small peaked structure diverting water around the back of the chimney — is required where the chimney dimension parallel to the ridgeline is greater than 30 inches and the chimney does not intersect the ridge. On a wide pre-war stack that is a real possibility and it is a roof-open decision.

The order matters, because water moves down. Starting where the stain is means starting at the end of the story.

1. 1

   Cap, crown, and the metal at the top

   Cap, chase cover, storm collar, arrestor screen, and fasteners, checked for perforation, scale, and open seams before anything else. On a shoreline address this is where the highest yield is.

2. 2

   All three flashing zones

   Under the crown, at the roof intersection, and at the chimney base. Whether counter flashing is genuinely let into a joint or simply stuck to the face, and whether anything is being held together with sealant.

3. 3

   The faces read separately

   The windward face and the sheltered face of the same chimney are not in the same condition here, and coastal guidance is explicit that exposure within a mile of the shore varies that much across one structure. A quote written from photographs of one side is a quote for half a chimney.

4. 4

   The masonry itself

   Joint erosion, spalled faces, cracks, plumb. Heavy wind-driven rain will penetrate a single wythe of brickwork regardless of materials or workmanship, so a single-wythe stack is read for how it drains rather than for whether it is watertight.

5. 5

   The inside

   Firebox, damper, smoke chamber, and the wall and ceiling surfaces around the chimney breast. Rust on a damper is a finding, not a cosmetic issue.

6. 6

   The flue, then the write-up

   A camera scan where the liner's condition is in question, and then a written scope and price that names the cause rather than the symptom, with urgent separated from what can wait and what needs nothing.

Chimney repair is a family of distinct jobs rather than one job. A diagnosis at an Everett address usually resolves to one or two of these.

• Cap or chase cover replacement. The most common single fix on a marine-exposed address, and the one that stops the most water for the least demolition. An unused flue collecting rainwater should get a ventilated cap as part of controlling moisture in the building.
• Crown repair or recasting. Where the slab across the top has cracked or lost its overhang. Weather-dependent work.
• Flashing rebuild. Base, counter, and through-wall flashing replaced as a system, with the counter flashing let back into the joints rather than sealed to the face.
• Repointing and brick replacement. Once the source above is closed. See chimney masonry repair for how mortar is selected on an older Everett stack.
• Relining. Where the flue itself has failed, which is established by a scan rather than inferred from the outside.
• Partial or full rebuild. Where the masonry above the roof line, or the whole stack, is past repointing. This is the scope most likely to bring a permit and, on some addresses, a historic review into the schedule.

Season is a real constraint here rather than a preference. Crown work, masonry, and repellent all need dry masonry and a dry forecast, and Everett's seasonal normals give 4.05 inches of precipitation across June through August against 12.66 across December through February. A leak reported in November is often stabilized temporarily and scoped properly for the summer, and that sequencing should be said out loud rather than discovered later.