Worker on a ladder at the gutter line of a Long Island house in autumn

Alec's Construction repairs chimneys in Islip, Suffolk County — crowns, caps, repointing, spalled brick and the roofline flashing — working out of the yard in East Patchogue.

What Chimneys Do Wrong in Islip

South of Montauk Highway the salt load shortens everything. Mortar joints on an exposed chimney weather faster here than inland, and galvanised caps and flashing rust out years before the masonry needs attention.

Flashing Before Masonry

If there is a stain on a ceiling anywhere near the chimney, the flashing is the first suspect and the masonry is the second. Chimney flashing is a two-part detail: step flashing woven in with the shingle courses, and counterflashing let into a cut in the mortar joint and lapped over the steps so water cannot get behind it.

What is on a great many Long Island chimneys instead is roof cement, troweled over the joint by somebody who was up there for a different reason. Roof cement is brittle within a few winters, it cracks, and it hides the failure while the water keeps going in. It also has to be chipped off before a proper repair can be made, which makes the eventual job larger.

Failed step flashing and old roof cement where a brick chimney meets the shingles

The Crown and the Cap Are Two Different Things

The crown is the sloped surface on the very top of the chimney, covering the brickwork around the flue tiles, and it is what keeps water out of the masonry. On a lot of houses here it is a thin skim of mortar troweled over the brick — never the right material, cracked within a decade. A proper crown is cast concrete, reinforced, sloped, with an overhang and a drip edge and a bond break at the flue tile.

The cap sits above the crown over the flue opening, and it keeps rain, snow, debris and animals out of the flue itself. It should be stainless, not galvanised: galvanised caps rust, streak the masonry below and end up in the yard. A blocked flue on a gas or oil appliance is a carbon monoxide problem, which makes the cap a safety item rather than only a maintenance one.

Repointing, and the Mortar That Matters

Failed, recessed or missing mortar joints get cut out to depth and repointed. On older chimneys the mortar has to be compatible with the existing masonry — a mortar that is harder than the brick will not let the wall move, and the brick takes the damage instead. That is a real decision, not a bag choice, and it is worth asking about.

Spalled brick gets replaced. Coating it or repointing around it leaves the failure in the wall.

Permits and Departments in Islip

Islip files with the Town of Islip, whose published permit guidance treats finish work differently from anything touching water, gas or electric. Repointing, crown and flashing repairs are generally maintenance rather than permitted alterations, but rebuilding a chimney above or below the roof line is a different scope, and we confirm with the department rather than assume.

Book It Before the First Fire

Masonry wants temperatures above freezing to cure, so chimney repointing and crown work are autumn jobs on Long Island and the calendar fills from September. Flashing, caps and sheet-metal work can be done later in the cold.

Free walkthrough in Islip. Alex goes up, photographs the crown, the cap, the joints and the flashing, and you get the photos whether or not you hire us.

Frequently Asked Questions

Does salt air affect an Islip chimney?

South of Montauk Highway, noticeably. Salt gets into masonry with the moisture and crystallises in the pores as it dries, which does mechanically what freezing does, and mortar joints on an exposed chimney weather faster here than inland. It also attacks metal, so the cap, the flashing and any steel lintel usually need attention before the brick does. Galvanised caps and flashing on this side of town rust out years early.

Why is my chimney brick flaking?

That is spalling: the brick absorbs water, the water freezes and expands, and it pushes the face of the brick off. Long Island gets a lot of these cycles because the winter temperature keeps crossing freezing rather than staying below it. The water usually comes from a cracked crown, failed mortar joints or an open flue, and fixing those stops it progressing.

Do I need the chimney swept as well?

Sweeping and inspection are a chimney sweep's work and they are worth booking before the first fire of the season — a build-up of creosote in a wood-burning flue is a fire risk and a blockage in any flue is a carbon monoxide risk. Our work is the structure: the masonry, the crown, the cap and the flashing. The two jobs sit alongside each other.

Can chimney work be done in winter?

Masonry repairs want temperatures above freezing for the mortar to cure properly, so repointing and crown work are autumn jobs and we book them accordingly. Flashing, caps, chase covers and sheet-metal work can be done in the cold. If you call us in January with a leak we will stop the water and schedule the masonry for the spring rather than lay mortar that will fail.

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Also Serving Islip

Work With Alec's Construction

This guide is written by the crew that does the work. See Alec's Chimney Repair service — repointing, crowns, caps and roofline flashing. One crew start to finish, free walkthrough and a written estimate inside 48 hours.

Booking the cold months now: we also handle Roofing and Seamless Gutters.

Get a Free Estimate from Alec's Construction

Working across Suffolk County since 2018, one crew from start to finish. We come out, look at the actual job, and put a written number in your hand — no pressure, no obligation.

Or call (631) 312-7441

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