InspectAPedia ®

Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice
Home | Air
Conditioning
| Electrical
-
Energy Saving
| Environment
Indoor
| Exteriors | Heating | Home
Inspection
| Insulate
-
Ventilate
| Interiors | Mold
Inspect/Test
| Plumbing
Water
Septic
| Roofing | Solar
Energy
| Structure | Contact Us
Directory of Professionals to Inspect or Test a Building


Mobile Phone/PDA website viewMobile View
STRUCTURAL INSPECTIONS & DEFECTS
CARBON MONOXIDE
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CHIMNEY INSPECTION & REPAIR GUIDE
Chimney Cleaning Advice, Procedures
Chimney Crack & Collapse Risks, Repairs
  Articles on Collapsing Chimneys
Chimney Draft & Performance
Chimney Inspection Checklist
Chimney Inspection Indoor Procedures
Chimney Inspection Outdoors From Ground
Abandoned Chimneys: Outdoors
Chimney Crack Detection & Diagnosis
Chimney Inspection Outdoors From Ground
  Foundation Support for Masonry Chimneys
  Chimney Leaning, Separation, Movement
  Leaning Chimney Repair Methods
Chimney Movement - Ongoing vs Static
Chimney Footing Defective / Missing
Chimney Height & Clearance
  Chimney Too Short
  Masonry Chimney Roof Clearance
  Adjacent Metal Chimney Separation
  Chimney Height for Types L & Type B Vents
    Table of B-Vent Clearances
  Wood burning Fireplace Roof Clearance
Three-Sided Chimneys: Outdoors
Chimney Inspection Outdoors at Rooftop
Chimney Cap & Crown Inspection
  Missing Chimney Rain Cap
  Damaged Masonry Chimney Cap or Crown
  Separation of Chimney Flues - Chimney Top
  Chimney Height Extensions
  Chimney Top & Clay Flue Tile Repairs
Masonry Chimney Top Damage
  Blocked Chimney Flues
  Angled Chimney Flues
  Flue Tile Damage in Chimneys
  Soot at the Chimney Top
Chimney Flashing Mistakes & Leaks
Chimney Crack Detection & Diagnosis
Chimney Shoulder Leaks
Chimney Exterior Spalling
Chimney Repair Methods
  Bracing for Masonry Chimneys
  Bracing for Metal Chimneys
  Bracing for Masonry Chimneys, Lateral
  Chimney Height Extensions
  Chimney Top & Clay Flue Tile Repairs
  Connecting Metal Chimney Sections
  Damaged Chimney flues: cracks, holes, spalling
  Draft Inducer Fans
  Leaning Chimney Repair Methods
  Re-Lining Choices for Masonry Chimneys
  Replacement Components for Metal Chimneys
Chimney Types & Materials
Chimney Cleanout Doors
CO2 TOXICITY
COALSTOVE SAFETY
COMBUSTION PRODUCTS & IAQ
DRAFT HOODS - gas fired
DRAFT REGULATORS - barometric dampers
ENERGY SAVINGS in BUILDINGS
Fire Clearances for Masonry Chimneys
Fire Clearances for Metal Chimneys
Fire Clearances, Single-Wall Metal Flues
Flue Sizing of Chimneys
Fire Stopping Between Floors
Flue Vent Connectors - Boilers, Furnaces
Chimney Inspection: Flue Interiors
Flue Interior Inspection Methods
ChimScan: Inspecting Flues by Cameras
Fuel Changes for Heating Appliances
Metal Chimneys & Flues
Connecting Metal Chimney Sections
Definitions of Chimney Types & Parts
Fire Clearances for Metal Chimneys
Indoor Hazards, Metal Chimney & Vent
  Metal Chimneys - Continuous
  Excessive Offset from Vertical in Chimneys
Replacement Components for Metal Chimneys
Types of Metal Chimneys, Vents
  Bracing for Metal Chimneys
Class A Chimneys, MetalBestos™
  Manufactured Chimneys
  Single-Wall Metal Vents & Chimneys
  Super Chimneys, 629 Chimneys
  Triple-Wall Metal Fireplace Chimneys
  Type B-Vents
  Type L Vents
    Chimney Height for Types L & Type B Vents
Wet time & Corrosion in Chimneys, Vents
Wood Framed Chimney Chases
Shared Chimney & Shared Flue Hazards
  Shared Chimney Flue Examples
  Exceptions: Shared Flues Permitted?
    Wood & Oil Fired Heaters
    Two Gas Fired Appliances Vent in One Flue
    Multiple Fireplaces Sharing One Flue
Fireplace Damage & Unsafe Hearths - Settlement
HEATING INSPECTIONS
HOME HEATING SAFETY
Lennox WARNING
Moisture Problems Damage Chimneys
OIL HEAT SAFETY INSPECTIONS
PLASTIC HEATER VENTS
PLASTIC VENTS Goodman HTPV RECALL
STAINS on chimneys
Transite Pipe Chimneys & Flues
UNLINED FLUE INSPECTIONS
Weil McLain RECALL
Wood Burning Heaters Fireplaces Stoves

More Information

InspectAPedia.comInspectAPedia ® Home & Site Map
InspectAPedia Blog - News Updates
Air Conditioning & Heat Pumps
Bookstore
Electrical
Environment
Exteriors
Heating
Home Inspection
Insulate Ventilate
Interiors
Mold Inspect/Test
Plumbing Water Septic
Roofing
Structure
Accuracy & Privacy Policies
Contact Us



Photograph of a damaged masonry chimney.

Chimney & Flue Inspection, at the Rooftop
InspectAPedia®  -    

  • Chimney inspection procedures on the rooftop: rooftop chimney defects
  • Detailed Inspection & Photo Guide to chimney defects
Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. Our contact info is at InspectAPedia.com/appointment.htm.

This article describes chimney defects that can best be spotted and diagnosed by on-roof access. These include inspection of the chimney cap and crown or top seal, the condition of the uppermost chimney flue, the separation of multiple chimney flues. Additional rooftop chimney inspection details are provided in subsequent sections of this article.

Climbing ladders and accessing roofs is inherently dangerous and was the cause of the first home inspector death recorded to have occurred during a home inspection. Home inspectors are not required to climb onto a roof which for any reason the inspector feels is unsafe or too fragile for direct access. However this article describes describes chimney defects which may be difficult or impossible to detect from a ground-level inspection. If you have not done so, see Chimney Inspection Outdoors From Ground. Readers should also see Chimney Crack & Collapse Risks, Repairs.

This website provides detailed suggestions describing how to perform a thorough visual inspection of chimneys for safety and other defects. Chimney inspection methods and chimney repair methods are also discussed. As with most inspection and safety topics, this material may be incomplete. © Copyright 2010 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Rooftop Chimney Inspection at the Rooftop

An on-roof inspection of the chimney allows inspecting the upper portion of the flue lining, cap and roof flashing, chimney top seal or "crown", and it permits a closer inspection of masonry chimneys for cracking or other damage that might not be visible from a more remote "from ground" inspection.

Suggestions for Inspecting Chimney Caps & Crowns

Chimney cap (C) Daniel FriedmanSome of us are confused about what to call the topmost components of a chimney.For clarity in this article, unless we state otherwise here is what we mean by "rain cap", "chimney cap" and "chimney crown":

Rain Cap: 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. The metal cover shown in our photo at left is a metal "rain cap".

Some people call this the rain cap.This interesting chimney has a metal cap on one flue and not the other. The metal chimney cap looks home-made and perhaps not functional.

Chimney Cap: 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 (above left) the chimney cap, also called a mortar cap, is the white concrete visible around the projecting flue tiles at the top of the chimney. Some of us call the mortar cap or concrete chimney cap the chimney crown. The Masonry Institute of America calls this the "chimney cap" - we're following their terminology.


Chimney cap and spark arrestor (C) Carson DunlopThe purpose of the chimney cap [chimney crown] is to close off the space between the flue liner and chimney wall, to shed water clear of the chimney and generally prevent moisture entry.

The rain rain cap has the job of keeping rain and wind down-drafts out of the chimney. The rain cap or hood may also be charged with preventing sparks from leaving the chimney - a fire safety measure shown in Carson Dunlop's Sketch.

The Brick Institute of America (BIA) recommends chimney caps of pre cast or cast-in- place concrete a minimum of 2-inch thick with a projection of 2 1/2-inch beyond the face of the masonry surround so that water shed from the top will not run down the face of the brick.


Chimney cap slope (C) Carson DunlopChimney cap slope: The chimney "cap" [or crown] should slope away from the flue at a good rate of about 3-inches per foot.

The chimney cap should not be bonded to the flue liner or top of the chimney in order to allow for thermal expansion of the liner. The space between the cap and the flue liner must be closed with a flexible sealant.

Mortar chimney "caps" are prone to cracks and allow water to drain over the face of the chimney masonry leading to spalling, loss of mortar and leakage to the interior spaces. Corrosion at the chimney base cleanout doors are common to those types of chimneys.

Check the chimney top for damaged masonry (or rusted metal), a missing cap, damaged, cracked, or missing top seal or crown on the top of a masonry flue, and here, an important discovery (at least in some jurisdictions) is whether or not the chimney is single wythe or thicker masonry and whether or not the chimney has (or perhaps needs) a chimney liner.


Lost rain cap (C) Carson Dunlop

Missing Chimney Rain Cap

If we want proof that people don't spend a lot of time looking at their chimney, ask a home inspector or chimney sweep how often they find that the rain cap or spark arresting chimney cap has been completely lost from a chimney.

As Carson Dunlop's sketch shows, a missing cap invites water damage to the chimney and the equipment it vents, draft problems, and unsafe operation. Water entering the chimney can cause enough corrosion in a metal flue that the chimney needs replacement.


Chimney top missing drop edge (C) Carson Dunlop

The concrete crown in our photo (above) looks recently installed and does not drain past the chimney sides. There has been water damage covered up with painted metal on the chimney side facing us.This chimney needs some safety inspection and probably new caps on the flues.

As Carson Dunlop's sketch shows (left), a good drip edge at the chimney top cap helps reduce water and frost damage to the chimney sides and structure. Watch out particularly for flat or even in-sloping metal caps on wood-framed chimney chases built around metal chimneys - these are often a source of hidden leaks into the structure and potentially dangerous rust or corrosion damage to fireplace inserts and flues as well as damage to heating equipment.


Chimney top cap construction details (C) Carson Dunlop

Carson Dunlop's sketche (left) show some details of good chimney cap construction. The object of these details is to avoid water and frost damage to the flue or to the chimney itself.

Chimney cap history: if a chimney has spent part of its life with no rain cap installed, or if the masonry cap is poorly constructed, there is extra risk of water damage to the flue interior.

In a masonry chimney damage may appear as frost cracking of the upper flue liners or masonry.

In any chimney, there may also be water damage to the heating appliances being vented by that chimney, such as rust, formation of corrosive condensate, or creosote.

Damaged Masonry Chimney Cap or Crown

Photograph of a cracked chimney top crown and no cap installed.

Chimney Cap: shown here is the concrete seal around the top of a chimney, sealing the upper chimney surface around the projecting chimney flue (clay flue tiles in this photo) in order to close off the space between the flue liner and chimney wall, to shed water clear of the chimney and generally prevent moisture entry.

Here is a chimney with a mortar cap but no rain cap. The design would have been better if one of the clay flue liners projected several inches higher than its neighbor, and if the concrete cap had been pre-cast or otherwise constructed to give an overhang past the sides of the chimney so that runoff would not wet and damage the brick masonry below.

Installation of this chimney cap would also have been better if there were an expansion gap and sealant permitting the flue tiles to expand without cracking the surrounding concrete cap.

Share this Article      

...

Technical Reviewers & References

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

CHIMNEY INSPECTION & REPAIR GUIDE
CHIMNEY INSPECTION DIAGNOSIS REPAIR
Chimneys Cleaning Advice, Procedures
Chimney Cleanout Doors
Chimney Crack & Collapse Risks, Repairs
Chimney Draft & Performance
Chimney Inspection Checklist
Chimney Inspection Indoor Procedures
Attic Chimney Inspection
Chimney Inspection Outdoors From Ground
Chimney Crack Detection & Diagnosis
Chimney Inspection Outdoors From Ground
Chimney Height & Clearance
Chimney Inspection Outdoors at Rooftop
Chimney Cap & Crown Inspection
  Missing Chimney Rain Cap
  Damaged Masonry Chimney Cap or Crown
  Separation of Chimney Flues - Chimney Top
  Chimney Height Extensions
  Chimney Top & Clay Flue Tile Repairs
Masonry Chimney Top Damage
  Blocked Chimney Flues
  Angled Chimney Flues
  Flue Tile Damage in Chimneys
  Soot at the Chimney Top
Chimney Flashing Mistakes & Leaks
Chimney Crack Detection & Diagnosis
Chimney Shoulder Leaks
Chimney Exterior Spalling
Chimney Cap & Crown Inspection
Chimney Types & Materials
Chimney Cleanout Doors
Fire Clearances for Masonry Chimneys
Fire Clearances for Metal Chimneys
Fire Clearances, Single-Wall Metal Flues
Flue Sizing of Chimneys
Fire Stopping Between Floors
Flue Vent Connectors - Boilers, Furnaces
Chimney Inspection: Flue Interiors
Metal Chimneys & Flues
Shared Chimney & Shared Flue Hazards
Fireplace Damage & Unsafe Hearths - Settlement
Moisture Problems Damage Chimneys
Wood Burning Heaters Fireplaces Stoves

  • Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
  • Thanks to Luke Barnes for suggesting that we add text regarding the hazards of shared chimney flues. USMA - Sept. 2008.
  • Arlene Puentes, an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at ap@octoberhome.com
  • Roger Hankey is principal of Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com
  • Residential Masonry Fireplace and Chimney Handbook, James E. Amrhein, S.E., MIA, Masonry Institute of America, 2d. Ed., 1995, ISBN 0-940116-29-4. The MIA is in Los Angeles, CA 213-388-0472. This manual reflects the 1994 Uniform Building Code, Energy Conservation Requirements of California, and the U.S. Department of Housing and Urban Development - HUD. The complete UBC is available from the International Conference of Building Officials (ICBO), Whittier CA 310-699-0541.
    • NFPA 211 - Standards for Chimneys & Fireplaces, NFPA 211: Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, 2006 Edition (older editions and standards are found at the same bookstore)
    • NFPA #211-3.1 1988 - Specific to chimneys, fireplaces, vents and solid fuel burning appliances.
    • NFPA # 54-7.1 1992 - Specific to venting of equipment with fan-assisted combustion systems.
    • GAMA - Gas Appliance Manufacturers' Association has prepared venting tables for Category I draft hood equipped central furnaces as well as fan-assisted combustion system central furnaces.
    • National Fuel Gas Code, an American National Standard, 4th ed. 1988 (newer edition is available) Secretariats, American Gas Association (AGA), 1515 Wilson Blvd., Arlington VA22209, and National Fire Protection Association (NFPA), Batterymarch Park, Quincy MA 02269. ANSI Z223.1-1988 - NFPA 54-1988. WARNING: be sure to check clearances and other safety guidelines in the latest edition of these standards.
    • Fire Inspector Guidebook, A Correlation of Fire Safety Requirements Contained in the 1987 BOCA National Codes, (newer edition available), Building Officials and Code Administrators International, Inc. (BOCA), Country Club HIlls, IL 60478 312-799-2300 4th ed. Note: this document is reissued every four years. Be sure to obtain the latest edition.
    • Uniform Mechanical Code - UMC 1991, Sec 913 (a.) Masonry Chimneys, refers to Chapters 23, 29, and 37 of the Building Code.
    • New York 1984 Uniform Fire Prevention and Building Code, Article 10, Heating, Ventilating, and Air Conditioning Requirements
    • New York 1979 Uniform Fire Prevention & Building Code, The "requirement" for 8" of solid masonry OR for use of a flue liner was listed in the One and Two Family Dwelling Code for New York, in 1979, in Chapter 9, Chimneys and Fireplaces, New York 1979 Building and Fire Prevention Code:
  • "Top Ten Chimney (and related) Problems Encountered by One Chimney Sweep," Hudson Valley ASHI education seminar, 3 January 2000, contributed by Bob Hansen, ASHI
  • Chimney Inspection Checklist, Carson Dunlop, Associates, Toronto, Ontario
  • "Rooftop View Turns to Darkness," Martine Costello, Josh Kovner, New Haven Register, 12 May 1992 p. 11: Catherine Murphy was sunning on a building roof when a chimney collapsed; she fell into and was trapped inside the chimney until rescued by emergency workers.
  • "Chimneys and Vents," Mark J. Reinmiller, P.E., ASHI Technical Journal, Vol. 1 No. 2 July 1991 p. 34-38.
  • "Chimney Inspection Procedures & Codes," Donald V. Cohen was to be published in the first volume of the 1994 ASHI Technical Journal by D. Friedman, then editor/publisher of that publication. The production of the ASHI Technical Journal and future editions was cancelled by ASHI President Patrick Porzio. Some of the content of Mr. Cohen's original submission has been included in this more complete chimney inspection article: InspectAPedia.com/chimneys/Chimney_Inspection.htm. Copies of earlier editions of the ASHI Technical Journal are available from ASHI, the American Society of Home Inspectors.
  • Natural Gas Weekly Update: http://tonto.eia.doe.gov/oog/info/ngw/ngupdate.asp Official Energy Statistics from the U.S. Government
  • US Energy Administration: Electrical Energy Costs http://www.eia.doe.gov/fuelelectric.html
  • Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

More expert information on this topic

STRUCTURAL INSPECTIONS & DEFECTS
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CHIMNEY INSPECTION GUIDE
HEATING SYSTEMS

More Information

InspectAPedia.comInspectAPedia ® Home & Site Map
InspectAPedia Blog - News Updates
Air Conditioning & Heat Pumps
Bookstore
Electrical
Environment
Exteriors
Heating
Home Inspection
Insulate Ventilate
Interiors
Mold Inspect/Test
Plumbing Water Septic
Roofing
Structure
Accuracy & Privacy Policies
Contact Us

More Information on Building Diagnostic Inspections and Repairs

  • NFPA 211 - 3-1.10 - Relining guide for chimneys
  • NFPA 211 - 3-2 - Construction of Masonry Chimneys
  • NFPA 211 - 3-3 - Termination Height for chimneys
  • NFPA 211 - 3-4 - Clearance from Combustible Material
  • NFPA 54 - 7-1 - Venting of Equipment into chimneys
  • Brick Institute of America - Flashing Chimneys
    Brick Institute of America - Proper Chimney Crowns
    Brick Institute of America - Moisture Resistance of Brick
  • American Gas Association - New Vent Sizing Tables
  • Chimney Safety Institute of America - Chimney Fires: Causes, Effects, Evaluation
  • National Chimney Sweep Guild - Yellow Pages of Suppliers
InspectAPedia.comInspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.
GO TO the MOLD and INDOOR ENVIRONMENT INFORMATION CENTER for in-depth advice on avoiding testing for or cleaning up mold and other indoor environmental hazards, odors, gases, contaminants
The Mold Information Center:
What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
GO TO MOLD TEST KITS: This expert-recommended mold test kit is cheap and yet top performing *IF* you use a competent analysis laboratory!
Use this simple, economical mold test kit
by following our instructions on how to collect and mail mold samples to our lab
GO TO IAQ/MOLD-TEST LAB SERVICES: Mold, Pollen, indoor air quality, field and laboratory services by an expert.Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.
GO TO our PRE PURCHASE BUILDING INSPECTION SERVICES: Authoritative information for home buyers and home owners is included with your inspection.
Building Inspection, Problem Diagnosis
, Forensic Investigation & Testing, Repair Consulting

CONTACT Daniel Friedman - Dan is a senior ASHI home inspector, nationally recognized expert on building inspection, building failures, and sick building investigation
Contact Daniel Friedman for website content suggestions or for fee-paid consulting

02/12/2009 - 01/27/1994 - InspectAPedia.com/chimneys/Chimney_Rooftop_Insp.htm - © 2010 - 1994 Copyright Daniel Friedman All Rights Reserved - InspectAPedia® is a Registered U.S. Trademark