How Much Does Chimney Cap Replacement Cost?

What you are actually paying for

A cap replacement bill has three parts: the cap itself, the labor to get to the chimney and fasten it properly, and any repair to the surface it fastens to. On a simple job the cap is the main expense. On a tall or awkward chimney, getting there safely can outweigh the part. And when the old cap failed because the tile or crown underneath was breaking up, the repair becomes the biggest line on the estimate.

Knowing which of the three is driving your price makes it much easier to compare two estimates. A low number that leaves out the repair, or quotes a stock cap for a flue that clearly needs a custom one, is not really a lower price.

Flue size and shape

Caps are made to fit standard clay flue tile sizes, square, rectangular or round. If your tile is a common size and sticks up cleanly above the crown, the cap is a stock part that clamps around it. That is the simplest and least expensive case.

Older chimneys across the boroughs, Jersey City, Philadelphia and Wilmington often break that pattern. Tiles may be an uncommon size, chipped at the top, sitting flush with a mortar wash, or missing entirely in a flue that was never lined. Those need an outside-mount cap whose legs fasten to the crown, or a cap made to measure. Measuring on the roof is how you find out which you have; a cap ordered from a guess either does not fit or sits loose and blows off later.

One flue or a whole stack

Plenty of brownstone, rowhouse and colonial chimneys carry several flues: a fireplace on each floor plus one for the boiler. Each can get its own cap, or one wide cap can cover the whole top. Single caps cost less apiece, but four of them add up, and each is one more set of fasteners to fail. A full-width cap is a larger, usually custom piece, and it needs a crown in good shape to sit on.

On a party-wall chimney that also vents the neighbouring home, a full-width cap covers both homes' flues. That can make sense for both owners, but it means agreeing on the design and the cost split before anything is ordered.

Material and how it holds up

The metal makes a real difference both in the price and in how long the cap stays on the chimney.

Mesh and the fuel below

The cap has to suit what the flue carries. A wood-burning fireplace takes a standard mesh that stops birds, squirrels and larger embers. An oil boiler sheds soot, and fine mesh on an oil flue can clog within a season and choke the draft, so the opening size has to match. A gas boiler or water heater vented through a stainless liner often needs the termination cap the liner or appliance maker calls for.

Getting this wrong does not show up on the day of installation. It shows up months later as a smoky fireplace or a boiler service call, which is why the estimate should say what each flue serves and which cap goes on it.

Access, height and the roof

Fastening the cap is usually quick. Getting to it is where the time goes. A three- or four-story rowhouse reached through a roof hatch is often easier than it sounds, because the roof is flat. A steep slate roof on a colonial, a chimney on the far side of a ridge, or a stack that can only be reached from a neighbour's roof adds time, ladders, roof protection and sometimes more crew.

Weather plays a part as well. Wind, ice and wet slate all slow the work or push it to another day, and a crew that will not work on an icy roof is doing the job correctly.

What turns up on the roof

Once up there, the crew sometimes finds that the old cap failed because of what is under it. A cracked flue tile, a crumbling crown or a thin mortar wash with no solid surface for fasteners has to be repaired before a new cap will stay put.

That repair is a separate item, and it should appear on its own line with a short explanation, not folded into the cap price. If it was not seen at the first visit, ask the crew to explain on the spot what they found and why it has to be done before the cap goes on.

• Chipped or cracked top of the flue tile
• Crown cracks or a mortar wash breaking away from the tiles
• Loose top courses of brick under the crown
• Debris, nests or fallen tile pieces collected at the bottom of the flue
• Rusted damper from years of rain falling into an uncapped flue

Comparing two estimates

Cap quotes are hard to compare when one is a single line and the other runs half a page. The details below are what separate a cap that lasts from one that comes down in the next storm, and a clear estimate states each of them.

If one quote is far below the others, check these points first. The gap is usually a galvanized cap instead of stainless, a stock size instead of a measured one, or a cap screwed into a crown that the cheaper estimate does not mention repairing.

• Which flues are covered, and whether by separate caps or one full-width cap
• The metal, and the mesh opening chosen for each fuel
• How the cap is fastened: clamp band on the tile, or anchors into the crown
• Any tile, crown or brick repair, listed and explained on its own line
• Removal of the old cap and any debris found in the flue
• A draft check on the heating flue after the cap is on

Why the cheap cap costs twice

A thin galvanized cap pressed onto a chipped tile is the lowest bid, and it is also the cap most often found in the gutter after a nor'easter. Paying once for a correctly sized, fastened stainless cap is usually less than paying for a cheap cap, its replacement and the water damage in between.

The fair way to price it is to measure first. Pro 1 Chimney measures each flue, checks the crown and gives a free written estimate that lists the cap, the installation and any repair separately, so you can see where every part of the price comes from.