Chimneys and Flues: Inspection Methods, Diagnosis, Safety, Repairs
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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.
Website content criticism, questions, and content suggestions are invited and we are pleased to give credit to contributors and technical reviewers.
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
Life Safety Hazards such as visual evidence of unsafe chimneys, fire hazards, flue gas and carbon monoxide hazards, missing or damaged safety devices (relief valves, emergency shutoffs),
and visual evidence of dangerous overheating or leaks. Life safety hazards also include collapsing chimneys.
Responsibly conducted, an inspection of a gas-fired furnace, for example, might
discover that the furnace has been exposed to severe rust-producing conditions which risk an unsafe heat exchanger and a carbon monoxide hazard
which could be fatal to building occupants.
Even though the interior of a chimney or flue is not fully visible, the contextual clues around the
chimney, if they are visually obvious, should be translated into a level of concern by the inspector, and where appropriate, translated into
a recommendation for action. This does not mean "failing" every chimney to be on the "safe side", it means responsible inspecting and reporting.
Costly defects such as evidence of movement, damage to masonry flues, including chimney collapse, metal chimney & flue pitting or rust, leaks and damage to metal flues,
and obvious gaps, openings, or lack of clearance to combustibles should be reported. Sketch showing the fire clearance requirements for metal chimneys (above), courtesy Carson Dunlop.
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Carson Dunlop, Associates, 120 Carlton Street Suite 407, Toronto ON M5A 4K2Toronto. (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.
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.
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
"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
Books & Articles on Chimney Inspection, Testing, Diagnosis, & Repair
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 & 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.
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)
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