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Chimney Rain Cap & Chimney Cap/Crown
Chimney Top Choices, Installation, Inspection, Defects & Repairs

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Chimney caps & crowns: this article describes the types of covers & terminations found at the top of chimneys and flues. We define chimney rain cap, chimney cap, chimney crown, and chimney pot, giving photo-examples of each of these components.

We illustrate common chimney cap & crown types, choices, & defects, and we cite pertinent chimney top cap / crown building codes & standards for fire and other safety concerns.

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Definitions of Chimney Rain Cap, Chimney Cap, Chimney Crown, Chimney Pot, Chimney Shroud

Chimney rain cap (C) Daniel Friedman

Some of us are confused about what to call the topmost components of a chimney. This article offers definitions of chimney rain cap or rain cover, chimney crown or top seal, chimney pot, and chimney shroud. Additional articles in this series describe inspection points, defects, and safety hazards concerning each of these chimney features.

Article Contents

Definition of Chimney Rain Cap or Rain Cover

A chimney rain cap is a rain cover on top of a chimney flue designed to keep out rain (which can damage the flue or appliances it vents) and intended to reduce downdrafts in the chimney in windy conditions.

Some chimney rain caps may be supported atop a masonry chimney in a position to shelter the chimney flue, and may not only cover the chimney flue opening but may also project out beyond the entire chimney top (red arrow, photo at left).

This example is still a chimney rain cap.

[Click to enlarge any image]

On many clay flue tile lined chimneys the rain cap will mount directly on to and will cover only the chimney flue itself (photo at left).

Metal raincap on chimney © D Friedman at InspectApedia.com

A retrofit chimney rain cap is shown in our photo.

This rain cap is designed to fit over the top of a standard sized clay chimney flue tile and is held in place by four threaded bolts that press against the sides of the flue tile.

Other chimney rain caps for clay tile flues mount by friction by insertion into the interior of the top of the flue tile.

Watch out: over tightening the securing bolts of this chimney rain cap can break the flue tile, while leaving them too lose risks that the whole rain cap assembly blows away during high winds.

Definition of Chimney Cap = Chimney Crown = Mortar Cap = Weather Cap

Photograph of a damaged masonry chimney.

Masonry Chimney Caps: on a masonry chimney the chimney cap is a pre-cast concrete or poured in place concrete seal around the flue tile (on a modern masonry chimney). In our photo (at left) the chimney cap, also called a mortar cap, is the gray concrete visible around the projecting flue tiles at the top of the chimney.

This particular chimney cap is defective: too thin, cracked, leaky, missing an expansion joint at the flue tile, and lacking a drip edge projection over the chimney top.

The Masonry Institute of America calls this chimney top surface seal around the flues the chimney cap. We're following their terminology.

Others call this area the "chimney crown" in an effort to avoid confusion between the chimney cap (red arrow) and the chimney rain cap (blue arrow). To add confusion "chimney crown" is used by others to refer to decorative chimney tops or pots (described below).

Details about how the chimney crown, also referred to as chimney weather cap, should be constructed are given

at CHIMNEY CAP / CROWN CONSTRUCTION


Metal chimney caps: the top of a wood-framed boxed-in structure through which a metal or insulated metal flue is routed must also be sealed against water using a chimney crown or cap, and the flue that extends through the chimney crown/cap also needs a rain cap. (Illustrated below)

Metal chimney cap assembly, Bar Harbor Maine (C) Daniel Friedman

Watch out: leakage into a chimney through a defective chimney cap leads to damage to the chimney structure, chimney flue, and leads to interior leaks as well as unsafe conditions.

Our photo of a metal chimney cap and rain-cap combined in a custom-fabricated design (at left), adds more confusion to chimney top terminology. This chimney was observed atop a hotel near Bar Harbor, Maine.

Definition of Chimney Pot

Chimney pot addition to an existing masonry chimney © D Friedman at InspectApedia.com

Our chimney pot photo (left) illustrates a retrofit or add-on chimney pot that increases the effective chimney height of a concrete block chimney, possibly aiding in solving a chimney draft problem.

As we show below and as we illustrate in more detail

at DECORATIVE CHIMNEY POTS,

Birds atop a chimney pot in Oxford in the U.K. (C) Daniel Friedman

the term "chimney pot" is used to describe a decorative rain cap assembly on the top of a chimney, covering its flue and in some cases covering both the flue itself and the entire chimney top, including the chimney flue and chimney cap/crown.

At above left is a common simple chimney pot installed on a New York home while at above right magpies are inspecting the chimney pots atop a chimney in Oxford in the U.K.

Decorative chimney pots in Boston MA (C) Daniel Friedman

Typically the chimney pot also adds height to the top of the chimney flue, as you can see in our photos above.

Chimney pots and chimney shrouds are described

at CHIMNEY POTS & DECORATIVE TOPS

Also see CHIMNEY HEIGHT EXTENSIONS.

Chimney Shrouds: for factory-built chimneys & chimney chases

Replacememt wood framed chimney chase top pan (C) Daniel Friedman Steve Werner - ChimneyKing.com

Chimney shrouds (above) are metal enclosures added atop a (typically wood-framed) chimney chase for cosmetic reasons, to hide the round or retangular metal chimney and rain cap that extend at the top of the chimney chase (below).

Replacememt wood framed chimney chase top pan (C) Daniel Friedman Steve Werner - ChimneyKing.com

Warning About Installing Decorative Chimney Top Shrouds (Chimney "Crowns") on Factory-Built Chimneys

Watch out: installing a decorative chimney pot or chimney crown on a factory-built chimney may be unsafe as well as a building code violation.

Unless the decorative chimney shroud or "crown" is listed and labeled for use with the specific factory-built chimney system where it is installed there is a risk that the added decorative covering can cause overheating, leading to a roof or chimney chase fire or other unsafe conditions such as inadequate draft.

- Thanks to Stephen Werner, Chimney King LLC in Gurnee, IL, for this warning. [5][35]

Details about decorative chimney top shrouds ("crowns" among some installers) installed atop wood-framed chimney chaseways, including model building code citations and fire safety warnings, are

at CHIMNEY SHROUDS.

Also see FIREPLACE INSPECTION PRE-FAB.

Photo of a listed decorative chimney top shroud (above left) provided courtesy of Chimney King. [5][35]

Define Chimney Corbeling

Corbelled chimney © D Friedman at InspectApedia.com

Chimney corbeling is stair-stepping a masonry chimney either to build it into an angle (photo above) or to widen the chimney base to accomodate a fireplace at the chimney base.

Above the corbelled chimney stair steps to one side in an attic in order to exit the roof right at the ridge rather than extending straight up from lower floors to a lower roof penetration location.

Watch out:

R1003.5 Corbeling.

Masonry chimneys shall not be corbeled more than one-half of the chimney’s wall thickness from a wall or foundation, nor shall a chimney be corbeled from a wall or foundation that is less than 12 inches (305 mm) thick unless it projects equally on each side of the wall, except that on the second story of a two-story dwelling, corbeling of chimneys on the exterior of the enclosing walls may equal the wall thickness.

The projection of a single course shall not exceed one-half the unit height or one-third of the unit bed depth, whichever is less. 

Source:

See also

Reader Question: What and where are the soffit, fascia board and are they parts of a chimney? What is a "corible"

Roof soffit and fascia parts (C) S BlissWhere is the "soffit" and "fascia board" on a chimney? I was told they need caulked. And what is a "corible". I was told it needs sealed. Thanks. - Rick

Reply: soffit and fascia are roof edge trim components. Corbelling is stair-stepping in brick work, often used to angle a chimney over to a desired location.

Rick, you got me on that question.

Soffits on building exteriors are the enclosed lower portion of the roof overhang or roof edge, also called "eaves".

See ROOF VENTILATION SPECIFICATIONS for photos & sketches of what roof soffits and fascias look like.

Your question worries me that you are not getting clear cogent advice.

Maybe ask whoever told you to be more clear.

The fascia board 

(green arrow in our sketch) is a vertical board running parallel to the roof edge on the outer edge of the soffit - usually it's covered by the roof edge gutters.

A soffit

 is a general term for a boxed-in overhang and might appear indoors in a kitchen over cabinets. In our roof sketch (left) the soffit is pointed to by our red arrow. The sketch at left is provided courtesy Steven Bliss & J Wiley & Sons [4]

A chimney doesn't have a soffit nor fascia, though a chimney built up along an outside house wall might indeed come into contact with or even penetrate a soffit and fascia along one of the roof edges.

But if your chimney runs up the outside wall of your home where it intersects with a lower roof edge, the soffit might be "interrupted" around the roof eaves in that area - and it's a common leak point.

Sadly it sounds as if you were getting questionable advice. What prevents leaks where a chimney passes through a roof, even at the lower edge or soffit or eaves of the house, is flashing, not caulking. Caulk would be a short-lived band aid.

Corbelling:

Corible - sounds like something "horrible" and isn't a word I've heard nor been able to find in building dictionaries except perhaps used as a term for button-like decorations around a section of building, roof, or chimney trim.

I suspect your contractor meant "corbelling" (photo above, some spell it corbelling) which refers to a stair-stepped or sometimes simply "slanted" chimney construction that allows the mason to angle a chimney off to one side in order to send it where the building designer or architect wanted.

Define Chimney Flue, Flue Damper, Flue-Vent-Connector

Fireplace damper viewed by looking up from inside a masonry fireplace (C) Daniel Friedman at InspectApedia.comReader Question: Definition of chimney flue. What is a chimney flue? What is a chimney flute?

Is it incorrect to say "close the flute" or is it "close the flue"? - Vanna 7/27/12

Reply: chimney flue - chimney flues vent heating appliances; flutes and even chimney "flutes" appear on pipe organs for making music.

Now about your question:

Define: A chimney flue damper

is a movable door or shutter located (in a fireplace) just above the fire-box or on some retrofit jobs located at the top of the chimney - operated by a pull chain or lever.

We close the chimney flue

by closing the flue damper - by moving a lever whose notches can hold the damper door open in various positions or permit it to close fully as the damper is shown in our photo above.

Some retrofit dampers are installed atop the chimney and are operated by a chain that hangs down the chimney flue.

Below we illustrate the major parts of a masonry fireplace including the flue damper - shown in blue.

Fireplace components (C) InspectApedia.com

Define: A chimney flue

(not flute) is the passage inside of a masonry chimney or inside of a metal chimney that allows smoke, heat, and gases of combustion to pass up the chimney to be vented safely above the building.

At a fireplace the chimney flue begins immediately above the smoke shelf above the fireplace itself.

At a heating appliance such as an oil or gas fired heating boiler or water heater, the active chimney flue begins at the point of insertion of the flue vent connector into the chimney.

Leaky flue vent connector at chimney (C) Daniel Friedman

Define: A flue vent connector is a metal pipe that connects the heating appliance to the chimney and chimney flue.

In our photo above our client is pointing to the (leaky) point at which a horizontal flue vent connector is inserted into the chimney flue. In our photo at left those two rectangular openings are the very top of two independent chimney flues.

See CHIMNEY INSPECTION, FLUE INTERIOR for details.

The term "chimney flute" does indeed occur and is used [correctly] to refer to certain German translations for pipe organ parts, and for pipe organ parts.

In documents describing the pipe organ - by which we refer to the musical instrument with a keyboard and air-driven sounding pipes that play various notes and chords - the term "flue pipe", "flute pipe", labial pipe, and also chimney flute all appear. In pipe organs, the "flutes" or "flute pipes" are the widest, elemental or low note producing pipes on the instrument. [24]

Watch out: However, perhaps from German or Old English, and also occasionally among people who are careless with language, we find articles written about heating appliance chimneys and flues that refer to the chimney "flute".

Baloney. If you come across a purportedly technical article about heating appliance chimneys that does not know the proper name for building parts, I'd be careful about trusting the advice offered there.

Chimney Cap / Chimney Crown Defect Inspection Guide

Separated masonry flues but at same height (C) Daniel Friedman

This topic is now found at CHIMNEY CAP & CROWN INSPECTION

Chimney Rain Cap / Rain Cover Inspection Guide to Defects

Metal raincap on chimney © D Friedman at InspectApedia.com

This topic is now located at CHIMNEY RAIN CAP / RAIN COVER INSPECTION

Home Made & Site-Built Brick Chimney Rain Caps & Chimney Caps: Combination Designs

Brick chimney rain cap and cap - San Miguel de Allende, Mexico (C) Daniel Friedman

We have moved this dicussion to CHIMNEY RAIN CAP / RAIN COVER DIY

Chimney Cap Clearance From Flue: Chimney Cap / Screen Vent Opening Dimensions

Squashed unsafe chimney rain cap (C) InspectAPedia TW

We have moved this discussion to a new article found at CHIMNEY RAIN CAP VENT OPENING SIZE

...

Continue reading at CHIMNEY CAP / CROWN CONSTRUCTION or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see CHIMNEY CAP & CROWN DEFINITIONS FAQs - questions & answers about the definitions and properties of chimney top parts found originally at this page.

Or see these

Chimney Top Cap, Crown, Rain Cap Articles

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CHIMNEY CAP & CROWN DEFINITIONS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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INDEX to RELATED ARTICLES: ARTICLE INDEX to CHIMNEYS & FLUES

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