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Chimneys and Flues: Inspection Methods, Diagnosis, Safety, Repairs ChimAPedia © How to inspect chimneys Unlined flue safety inspections & repairs Carbon monoxide & flue gas hazards Heating safety inspections Heating and chimney product recalls Woodstove safety inspections

Chimneys and Flues: Inspection Methods, Diagnosis, Safety, Repairs

This document explains how to inspect and detect defects and hazards in chimneys and flues. We also provide chimney repair advice, chimney repair alternatives. Chimney and flue safety hazards such as carbon monoxide gas leaks, fire hazards, and chimney inspection and testing are addressed.

In the photo shown here, a single wythe brick flue had lost some of its bricks. The owner "fixed" this condition by propping a board against a piece of aluminum flashing to cover the hole in the chimney.

Where do you think the missing bricks were? They were not on the attic floor. I had been called to the building to investigate a basement water entry problem.

This is what we found: a single wythe brick chimney in a tall two story house with full basement.

The water on basement walls was condensate from flue gas spillage from the gas fired heating boiler whose flue was totally blocked by the fallen bricks and debris. This was a serious carbon monoxide hazard and a dangerous chimney. The details of this case are presented at "Unlined Chimney Flues" - see links below.

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© Copyright 2009 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.

• Carbon Dioxide Gas Toxicity
• Carbon Monoxide Gas Toxicity, exposure limits, building inspection for CO hazards
• Chimneys & Flues - Detailed Inspection Procedures: safety concerns, chimney inspection methods, chimney repair methods, chimney relining methods, chimney replacement, new installation alternatives; and direct-vent alternatives to chimneys for heating furnaces & boilers
• Unlined Chimney Flues: Inspection Procedures, Advice Safety Requirements for old chimneys - photos, dangerous carbon monoxide and blocked flue case report, chimney flue standards, chimney inspection suggestions
• Chimney Safety Alert for Wood Burning Appliances - US CPSC Alert Document 5017, wood stoves, fireplace inserts
• Chimney Safety Alert for Metal Chimneys - US CPSC Alert Document 5047, metal chimneys, wood and coal stove safety
• DRAFT HOODS - gas fired heating appliance control for safe venting of combustion gases from the heater into a chimney
• DRAFT REGULATORS - barometric dampers Oil fired heating appliances (furnaces, boilers, water heaters) are connected to a chimney to vent combustion gases; the draft regulator or "barometric" damper is needed to assure both the proper amount of draft and its consistency
• Goodman Furnace High Temperature Plastic Vent HTPV safety recall US CPSC notice
• Home Heating System Should Be Checked [for proper venting and for CO Carbon Monoxide Hazards - DJF]
• Inspection Procedures for Oil-Fired Heating Systems Detailed step by step approaches for inspecting complex systems]
• Lennox Pulse Furnace Safety Inspection/Warranty Program: Carbon Monoxide Warning
• Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
• Stains on chimneys - what do white or brown stains mean on a masonry chimney exterior surface?
• Transite Pipes, Chimneys & Flues - Safety Hazards of deteriorated or blocked asbestos transite chimneys
• Weil McLain Model GV Gas Boiler/gas valve CPSC recall/repair

Critical Chimney, Vent, & Flue Defects

CHIMNEY INSPECTION & REPAIR GUIDE provides a detailed guide to visual inspection of all types of chimneys and flues.

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Technical Reviewers & References

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• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also list books on the specific article topic as well as other references, and information sources.
• Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Additional technical contributors & reference sources listed below

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.

STRUCTURAL INSPECTIONS & DEFECTS
BAROMETRIC DAMPERS
CARBON MONOXIDE/DIOXIDE
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CHIMNEY INSPECTION & REPAIR GUIDE
Chimney Components Definitions
Abandoned Chimneys
Backdrafting Appliances
Chimneys Cleaning Advice, Procedures
Chimney Cleanout Doors
Chimney Crack & Collapse Risks, Repairs
Chimney Crack Detection & Diagnosis
Chimney Leaning, Separation, Movement
Chimney Draft & Performance
Chimney Height & Clearance
Chimney Inspection Checklist
Most Frequent Chimney Defects
Chimney Inspection Checklist - Outdoors
Chimney Inspection Checklist - Indoors
Responsibility of an ASHI Home Inspectors
Chimney Inspection: Flue Interiors
Flue Interior Inspection Methods
ChimScan: Inspecting Flues by Cameras
Chimney Inspection Indoor Procedures
Blocked Chimney Flues
Chimney Crack Detection & Diagnosis
Dead End Chimney Flue Hazards
Fire Clearance Safety Hazards
Fire stopping at Chimney Passage Through Floors
Transite Pipe Chimneys & Flues
Chimney Inspection Outdoors From Ground
Chimney Inspection Outdoors at Rooftop
Angled Chimney Flues
Blocked Chimney Flues
Chimney Cap & Crown Inspection
Chimney Crack Detection & Diagnosis
Chimney Exterior Spalling
Chimney Flashing Mistakes & Leaks
Chimney Height Extensions
Chimney Shoulder Leaks
Flue Tile Damage in Chimneys
Masonry Chimney Top Damage
Soot at the Chimney Top
UNLINED FLUE INSPECTIONS
Chimney Repair Methods
Chimney Types & Materials
CO2 TOXICITY
COALSTOVE SAFETY
COMBUSTION GASES & PARTICLE HAZARDS
COMBUSTION PRODUCTS & IAQ
Dead End Chimney Flue Hazards
Definitions of Chimney Types & Parts
DRAFT HOODS - gas fired
DRAFT REGULATORS, DAMPERS, BOOSTERS
Fire Clearances for Masonry Chimneys
Fire Clearances for Metal Chimneys
Fire Clearances, Single-Wall Metal Flues
Fireplace Damage & Unsafe Hearths - Settlement
Flue Sizing of Chimneys
Flue Vent Connectors - Boilers, Furnaces
Fuel Changes for Heating Appliances
HEATING INSPECTIONS
HOME HEATING SAFETY
Lennox WARNING
Metal Chimneys & Flues
Bracing for Metal Chimneys
Class A Chimneys, MetalBestos™
Connecting Metal Chimney Sections
Continuous metal chimneys
Definitions of Chimney Types & Parts
Fire Clearances for Metal Chimneys
Height required for L Vents & B Vents
Indoor Hazards, Metal Chimney & Vent
Manufactured Chimneys
Offset from Vertical in Chimneys, excessive
Replacement Components for Metal Chimneys
Single-Wall Metal Vents & Chimneys
Super Chimneys, 629 Chimneys
Triple-Wall Metal Fireplace Chimneys
Type B-Vents
Type L Vents
Wet time & Corrosion in Chimneys, Vents
Wood Framed Chimney Chases
Moisture Problems Damage Chimneys
ODORS FROM HEATING SYSTEMS
OIL HEAT SAFETY INSPECTIONS
PLASTIC HEATER VENTS
Safety Recalls
Shared Chimney & Shared Flue Hazards
Stains on chimneys
Transite Pipe Chimneys & Flues
UNLINED FLUE INSPECTIONS
Wood Burning Heaters Fireplaces Stoves
Coalstove Safety
Dead End Flues - Dead Base Chimney Hazards
Fire Clearance Safety Hazards
Fire stopping at Chimney Passage Through Floors
HEATING COST FUEL & BTU Cost Table
Woodstove Safety

• Chimney Building Codes and Chimney, Flue, and Appliance Venting Standards
  • 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
• "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: inspect-ny.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

Books & Articles on Chimney Inspection, Testing, Diagnosis, & Repair

• Books, Complete List of Fireplace & Chimney Design, Inspection, Repair Books at the InspectAPedia Bookstore.
• Ceramic Roofware, Hans Van Lemmen, Shire Library, 2008, ISBN-13: 978-0747805694 - Brick chimneys, chimney-pots and roof and ridge tiles have been a feature of the roofs of a wide range of buildings since the late Middle Ages. In the first instance this ceramic roofware was functional - to make the roof weatherproof and to provide an outlet for smoke - but it could also be very decorative.
  The practical and ornamental aspects of ceramic roofware can still be seen throughout Britain, particularly on buildings of the Victorian and Edwardian periods. Not only do these often have ornate chimneys and roof tiles but they may also feature ornamental sculptures or highly decorative gable ends. This book charts the history of ceramic roofware from the Middle Ages to the present day, highlighting both practical and decorative applications, and giving information about manufacturers and on the styles and techniques of production and decoration.
  Hans van Lemmen is an established author on the history of tiles and has lectured on the subject in Britain and elsewhere. He is founder member and presently publications editor of the British Tiles and Architectural Ceramics Society. Available at the InspectAPedia Bookstore.
• Chimney Inspection Checklist, Carson Dunlop, Associates, Toronto, Ontario
• Chimney & Stack Inspection Guidelines, American Society of Civil Engineers, 2003 - These guidelines address the inspection of chimneys and stacks. Each guideline assists owners in determining what level of inspection is appropriate to a particular chimney and provides common criteria so that all parties involved have a clear understanding of the scope of the inspection and the end product required. Each chimney or stack is a unique structure, subject to both aggressive operating and natural environments, and degradation over time. Such degradation may be managed via a prudent inspection program followed by maintenance work on any equipment or structure determined to be in need of attention. Sample inspection report specifications, sample field inspection data forms, and an example of a developed plan of a concrete chimney are included in the guidelines. This book provides a valuable guidance tool for chimney and stack inspections and also offers a set of references for these particular inspections.
• Fireplaces, a Practical Design Guide, Jane Gitlin
• Fireplaces, Friend or Foe, Robert D. Mayo
• NFPA 211 - Standards for Chimneys & Fireplaces, NFPA
• Principles of Home Inspection: Chimneys & Wood Heating (Principles of Home Inspection), Carson Dunlop
• Woodstove & Fireplace Maintenance & Safety, L. L. Helwig

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