Outdoor Chimney Inspection, from the Ground
Ground-level detection of
Leaning Moving or Separating Chimneys
CHIMNEY LEANING, SEPARATION, MOVEMENT: OUTDOORS - CONTENTS: Ground-level chimney inspections: curved, collapsing chimneys. Evidence of chimney foundation defects. Leaning, separated or cracked chimneys; missing chimney supports. Collapsing metal chimneys. How to detect chimney movement. What causes chimney movement or collapse
Other chimney defects & hazards visible by outdoor ground-level inspection
Overgrown chimneys & flues - trim back vegetation
Bird or other animal nests in or on chimneys - fire & gas hazards
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This article describes chimney inspection procedures and critical chimney defects which can be observed from outdoors at ground level. We begin with the detection of chimney movement, its causes, its symptoms.
These articles continue with other chimney defects that can be found by visual inspection from outdoors at ground level, then from an on-roof inspection, followed by indoor inspections and ending with chimney-flue interior inspections.
Chimney leaks: water leaking into the chimney interior or structure, such as efflorescence, frost cracking, spalling
Chimney cap missing, chimney cap not draining; wrong type of cap for flue type or items being vented
Chimney crown cracked, damaged, missing, leaking, or not properly sloped to drain off of the chimney top; no drip edge over chimney sides. Some experts including Al Carson call our "crown" the chimney cap. Sketch above showing the basic parts of a masonry chimney is courtesy of Carson Dunlop.
Chimney type & usage: chimneys improperly shared among appliances, building rooms or building floors, or chimneys of the wrong type in use.
We describe these and other chimney defects in detail in the following sections of this article.
Chimney Separation from House, Settlement, Leaning, Movement, Cracking
A chimney which has settled and moved away from the building is almost certainly a serious safety hazard risking fire and flue gas leaks into the structure, and it is likely to require costly repairs or complete reconstruction. Details of how to see and evaluate chimney movement and separation are provided here.
Foundation Support for Masonry Chimneys
A summary of the chimney footing problem is just below.
What happens if a chimney footing is missing or inadequate? Masonry chimneys represent a heavy concentrated load on the soil or
support structure. Therefore, proper footing support is critical and is generally
separated from the building footings except possibly at the exterior wall.
Some masonry chimneys are constructed with an inadequate footing, or no supporting footing whatsoever. Future settlement, movement, tipping, or separation of the chimney from the building is certainly likely in such installations.
Even a casual inspection from outside would raise the question about the absence of a footing for the chimney shown in our photo. You will notice the erosion of soil from below a little concrete skirt around the chimney base of this concrete block chimney.
Homes built upon dry-laid stone foundations may have a chimney installed with its base sitting atop the foundation wall itself. Those chimneys might be stable, but be sure to review our warnings about dead end flues that are usually in use where such chimneys were built with no extension very far below ground level.
We continue below with an explanation of the causes of chimney movement, followed by a demonstration of how we spot evidence that chimney movement has been ongoing. Other articles in this series outline most other chimney defects that can be found outdoors or indoors on buildings.
At CHIMNEY MOVEMENT CAUSES we explain the common causes of chimney cracking, separation, leaning, tipping, or collapse.
At CHIMNEY MOVEMENT, ONGOING vs STATIC we continue this article with a case reporting evidence of ongoing chimney movement, repeated repairs, and the need to remove and rebuild a large masonry chimney.
Other Chimney Defects Visible by Outdoor Ground-Level Inspection
Overgrown chimneys & flues - trim back vegetation
Watch out: As you can certainly see from our photos above, tree, shrubbery or vine growth close to or covering a chimney can be a serious or even fatal hazard including risk of
Fatal carbon monoxide poisoning of the building occupants - venting a gas appliance into a chimney that is blocked by over-growth or blocked by anything else is likely to both cause production of high levels of carbon monoxide (especially from gas fired heating equipment) and to cause the fatal venting of carbon monoxide back into the building.
House fire - when chimney sparks ignite dried vegetation
Chimney structural damage as vine growth holds moisture on or in the chimney surfaces
Bird or other animal nests in or on chimneys - fire & gas hazards
As you can certainly see from our photo (left), this chimney, located in Rabat, Morocco, serves as a home for a stork's nest. This chimney top is essentially totally blocked by highly-combustible material - a bird's nest.
Watch out: even in areas where storks are not common, other smaller birds, squirrels, and some other animals may make a smaller nest inside the chimney or its flue, presenting hazards of blocked flue, fire, and potentially fatal carbon monoxide poisoning.
Risk of Hidden Chimney Damage - hybrid structures
This next chimney shown at below left ... well we're not sure what the heck we've got here.
We see a fired clay masonry flue tile projecting through a flat, leaky, too small, metal chimney cap surrounded by a wood and plywood structure.
We suspected that this was a masonry chimney that had suffered frost damage.
The owner installed a new clay flue tile at the very chimney top and boxed in the masonry chimney to cover the frost-damaged chimney structure (the home was being sold).
We've got a few concerns:
a missing rain cap - risking hidden damage to flue, flue vent connectors, heating equipment below
a defective leaky chimney cap or crown risking hidden damage to the chimney itself
wood framed covering over a chimney of uncertain material and condition, possibly adding to the fire hazard
a risk of hidden damage, unsafe flue, fire hazards, flue gas leak hazards
See CHIMNEY CAP & CROWN for definitions of chimney rain cap, chimney cap, chimney crown, and for more examples of chimney top defects that may be visible from the ground or from an on-roof inspection.
Poorly-secured or poorly-supported factory-built chimneys risk collapse
As you can certainly see from our photo (left), this chimney is collapsing and is unsafe.
After reviewing this "ground level chimney inspection guide" readers should then review CHIMNEY INSPECTION at ROOFTOP which describes chimney defects which may be difficult or impossible to detect from a ground-level inspection.
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Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: email@example.com
Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program. Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Home Reference Book, a reference & inspection report product for building owners & inspectors. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
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 firstname.lastname@example.org
Roger Hankeyis 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 #211-3.1 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.
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_Repair.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
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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.