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Inspection & Assessment of Abandoned Chimneys in buildings InspectAPedia®  -     Definition of abandoned chimney or flue Where do we find abandoned chimneys in buildings? What are the risks associated with abandoned chimneys? Questions & answers about abandoned chimney detection, inspection, hazards, removal or repair

This article describes the discovery, inspection, and significance of abandoned chimneys in buildings. By "abandoned chimney" we do not mean simply a chimney that is not in use.

A greater concern are chimneys that have been only partially removed, may not be adequately supported, and risk collapse, fire spread, heat loss, and other building concerns. Our photo (above) shows the abandoned chimney in the attic below the corrugated metal roof in the photo shown in our outdoor chimney inspection section. Happily this chimney was not in use at the time of our inspection. Do you suppose someone might some day try to use this flue without checking it out first?

Readers should also see Abandoned Chimneys: Outdoors and then Chimney Crack & Collapse Risks, Repairs.

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. As with most inspection and safety topics, this material may be incomplete.

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Inspection & Assessment of Abandoned Chimneys in buildings

Abandoned chimneys may be discovered in an attic, basement, or even in the middle of a structure, and can be a big surprise. We often wonder what's holding up all this weight.

Someone may have eliminated a fireplace or an entire chimney on the lower floors, but neglected to remove the chimney from the attic out through the roof, perhaps because they didn't want to repair the ensuing hole in the roof left if the chimney were removed.

Point loads from unanticipated weight or even a sudden collapse can be a real hazard if chimney bricks suddenly come through an upper floor bedroom ceiling.

see Chimney Collapse Hazards & Chimney Support & Bracing Requirements.

Our photo (above) shows an unsupported chimney in the top floor of a pre-1900 home. This chimney has it all (bad): the masonry chimney rests on floorboards between floor joists - it does not support its own weight. The chimney is cracked, damaged, and has evidence of a fire. The hole in the floor at the base of the chimney was a passage for a woodstove flue vent connector (with no fire protection or clearance) that connected into the upper opening in the chimney. At Chimney Cleanout Doors and at Flue Vent Connectors - Boilers, Furnaces we show a closeup of the lower cleanout opening - which was blocked by falling debris.

Carson Dunlop's sketch (above right) demonstrates the need to repair the roof and add support where a through-roof chimney is removed above the roof line.

Fire & Gas Hazards of Abandoned Chimney Flue Openings

Look for unsupported or inadequately supported masonry left in the building, sagging floors, or worse, on occasion you may find that the chimney was only "abandoned" above the roof, and that it continues to vent into the building attic. We found just that condition in a chimney trying to vent a gas fired furnace.

Our photo (above left) shows fiberglass stuffed into a round hole in a building surface. Regardless of whether you see this clue in a floor, ceiling, or wall, some investigation for the presence of a chimney behind the opening is an important safety check. Older homes were sometimes constructed with a single flue chimney that served appliances on multiple floors - an unsafe practice that is prohibited by modern building and fire codes.

Carson Dunlop's sketch (above right) shows a common "pie plate" cover over an un-used chimney opening. For safety the opening should be filled in with masonry. Be sure the repair leaves masonry flush with the chimney interior, not just the chimney's exterior side. Otherwise the repair may interfere with draft and it may make cleaning the flue difficult or impossible.

When an upstairs woodstove is removed the hole left in the chimney is best sealed with masonry material, not a metal cover plate, not insulation, not wood or drywall. Closing a chimney opening with those less durable materials leave a fire and flue gas leakage risk in the building.

A List of Abandoned Chimney Hazards on buildings

Some of the hazards associated with incomplete removal of a masonry or even a metal chimney in a building include:

• Fire spread in the building: an un-sound chimney may speed the spread of a building fire between floors
• Air quality and air safety: an un-used chimney may increase the flow of toxic gases from a problem area upwards into other building rooms, such as a smoke, soot, or potentially fatal carbon monoxide generated by heating appliance that is malfunctioning in a lower building area. Drafts can also move moisture and toxic mold spores or allergens and other problematic particles in a building.
• Bracket chimneys: old incomplete and possibly inadequately supported masonry chimneys in buildings - see Bracket Chimney Collapse & Fire Risks for details.
• Structural collapse: an old chimney may collapse causing damage or even injury to people at lower floors in the building. see Chimney Collapse Hazards & Chimney Support & Bracing Requirements.

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CHIMNEY INSPECTION DIAGNOSIS REPAIR

• 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
• Chimney Inspection Checklist, Carson Dunlop, Associates, Toronto, Ontario
• 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