Three Wall Chimney Hazards (C) Carson Dunlop

Examples & List of Indoor Fire Clearance Safety Hazards

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Chimney fire clearance specifications for inside the building
What is a three-sided chimney?
How can we spot a 3-sided chimney?
Why is a three-sided chimney dangerous?
Questions & answers about fire hazards that occur from various improper combustible clearances for chimneys and indoor building surfaces

Fire clearance hazards - unsafe indoor combustible clearances, & hazardous chimney clearances to indoor surfaces: this article describes common indoor fire clearance safety hazards.

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Indoor Fire Clearance Safety Hazards

Here is a list of articles describing in more detail a variety of fire hazards that occur because of inadequate distance between a heating appliance, flue vent connector, chimney, or other building component and combustible materials.

Our page top sketch of a three-sided chimney is courtesy Carson Dunlop. These articles on chimneys and chimney safety provide 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.

Fire Clearances for several common types of manufactured chimneys are summarized at Fire Clearances for Metal Chimneys and just below are links to the specifications of each type of manufactured or metal chimney:

Class A Chimneys, MetalBestos™
Type B-Vents
Type L Vents
Triple-Wall Metal Fireplace Chimneys
Super Chimneys, 629 Chimneys
Connecting Metal Chimney Sections
Wood Framed Chimney Chases

Fire Clearances for Masonry Chimneys

Fire Clearances for Metal Chimneys

FIRE CLEARANCES, Single-Wall Metal Flues includes the following detailed articles
  CHIMNEY HEIGHT & CLEARANCE CODE - a chimney that is too short can cause a roof fire
  Reduction in Fire Clearance - Heat Shields - to reduce the required fire clearance distance for a woodstove or other heating appliance or its flue vent connector
  Single Wall Metal Flues - Oil fired heaters - fire clearance requirements
  Single Wall Metal Pipe Flues - Gas heaters - fire clearance requirements - the distance to the nearest combustible surface
  Wood & Coal Stove Flues - fire clearance requirements - the distance to the nearest combustible surface
  Fire Clearance Safety Hazards, other - typical indoor fire clearance safety hazards listed with links to key articles

Fire stopping at Chimney Passage Through Floors explains the need for a block to natural chimneys that can occur in building walls, speeding the spread of a building fire

Flue Vent Connectors - Heating Boilers, Furnaces, etc - the flue vent connector is a metal pipe connecting a heating furnace, boiler, or other heating appliance to its chimney. Failure to respect the necessary distance between the flue vent connector and combustible surfaces is one of the most common fire hazards in buildings. See Indoor Chimney & Vent Connector Fire Clearances for details of this topic.

Holes in Masonry Chimneys often are not noticed by building owners who do not enter attics or attic knee wall spaces where an older masonry chimney, particularly a brick chimney, may have lost bricks, cracked, or moved, creating a serious fire hazard.

Three-Sided Chimneys - Three-sided chimneys - chimneys which do not provide full masonry thickness or fire protection around all sides of the chimney flue.

Wood Burning Boilers, Furnaces Fireplaces Stoves are often installed without a building permit and without safety inspections.

Particularly when heating costs for conventional heating oil and gas are rising and high, these devices see extra service and may be run longer or hotter than usual in a home. The result is an increase in house fires where wood stoves, coal stoves, or fireplace inserts have been improperly installed or where the chimney has become creosote-laden and catches on fire.

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Questions & answers about fire hazards that occur from various improper combustible clearances for chimneys and indoor building surfaces.

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Technical Reviewers & References

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CHIMNEY HEIGHT & CLEARANCE CODE
  Adjacent Metal Chimney Separation
  B-Vent Clearances Table
  Chimney Too Short
  Chimney Height Extensions
  Chimney Height for Types L & Type B Vents
  Fire Clearances for Masonry Chimneys
  Fire Clearances for Metal Chimneys
  FIRE CLEARANCES, Single-Wall Metal Flues
  Masonry Chimney Roof Clearance
  Wood burning Fireplace Roof Clearance

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
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

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Fireplace & Chimney Design, Repair Books - Fireplaces, Chimneys: design, repair
Fireplace & Chimney Inspection Books - Inspecting and diagnosing chimney problems, fireplace problems, chimney & fireplace standards
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 211: Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, 2006 Edition (older editions and standards are found at the same bookstore)
Principles of Home Inspection: Chimneys & Wood Heating (Principles of Home Inspection), Carson Dunlop
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
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Indoor Fire Clearance Safety Hazards

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