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Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair | Ask a Question or Search InspectAPedia |
 Mobile ViewCHIMNEY INSPECTION DIAGNOSIS REPAIR Abandoned Chimneys - Indoor Inspection Abandoned Flue Openings List of Abandoned Chimney Hazards Abandoned Chimneys: Outdoors Angled Chimney Flues ARCHITECTURE & BUILDING COMPONENT ID Attic Chimney Inspection Holes in Masonry Chimneys Dark Stains on Chimney Surface White/Light Stains on Chimneys Backdrafting Appliances BAROMETRIC DAMPERS Blocked Chimney Flues Bracket Chimney Collapse & Fire Risks B-Vent Chimneys B-Vent Clearances Table CARBON DIOXIDE - CO2 CARBON MONOXIDE - CO CHIMNEY INSPECTION & REPAIR GUIDE Chimney Cap & Crown Inspection Missing Chimney Rain Cap Damaged Masonry Chimney Cap or Crown Masonry Chimney Top Damage Separation of Chimney Flues - Chimney Top Soot at the Chimney Top UNLINED FLUE INSPECTIONS Chimney Cleaning Advice, Procedures Chimney Cleaning Fraud Warning Chimney Cleanout Doors Chimney Cleanout Combustible Clearance Chimney Cleanouts Required ChimScan: Inspecting Flues by Cameras Masonry Fragments & Debris at the Cleanout Missing Chimney Cleanout Door Chimney Components Definitions Chimney Crack & Collapse Risks, Repairs Articles on Collapsing Chimneys Bracing for Masonry Chimneys Bracing for Masonry Chimneys, Lateral Bracing for Metal Chimneys Bracket Chimney Collapse & Fire Risks Earthquake Chimney Collapse Dangers Chimney Crack Detection & Diagnosis Chimney Leaning, Separation, Movement-Outdoors Cracked Brick Chimney Sides Cracked Concrete Block Chimneys Curved Brick Chimneys Split Openings in Brick & Chimney Collapse Chimney Draft & Performance Draft: Thermal Performance of Chimneys Chimney Flashing Mistakes & Leaks 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 Chimney Height Extensions 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 Chimney Interior Inspection Methods Barometric Damper view of Flue Chimney Thimble Requirements Chimney Thimble Damage Cleanout Door view of Flue Masonry Fragments & Debris at the Cleanout ChimScan: Inspecting Flues by Cameras Chimney Inspection Indoor Procedures Chimney Inspection Outdoors From Ground Abandoned Chimneys: Outdoors Chimney Crack Detection & Diagnosis Chimney Footing Defective / Missing Chimney Leaning, Separation, Movement Foundation Support for Masonry Chimneys Three-Sided Chimneys: Outdoors Chimney Inspection Outdoors at Rooftop Angled Chimney Flues Blocked Chimney Flues Chimney Cap & Crown Inspection Missing Chimney Rain Cap Damaged Masonry Chimney Cap or Crown Separation of Chimney Flues - Chimney Top 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 Leaning, Separation, Movement Chimney Movement - Causes Chimney Movement - Ongoing vs Static Chimney Footing Defective / Missing Foundation Support for Masonry Chimneys Leaning Chimney Repair Methods Chimney Repair Fraud Warning Chimney Repair Methods Bracing for Masonry Chimneys Bracing for Metal Chimneys Bracing for Masonry Chimneys, Lateral Chimney Height Extensions Chimney Top & Clay Flue Tile Repairs Connecting Metal Chimney Sections Damaged Chimney flues: cracks, holes, spalling Draft Inducer Fans Leaning Chimney Repair Methods Re-Lining Choices for Masonry Chimneys Replacement Components for Metal Chimneys Chimney Safety - CPSC Alert Chimney Shoulder Leaks Chimney Spalling, Exterior Chimney Sweeps Chimney Types & Materials Device Categories vs. Chimney Requirements Double-Wall Metal, Type B & Type L Chimneys Draft Hood Appliances Factory Built Chimneys High Efficiency Heating Appliances High Temperature Plastic Chimneys & Vents Masonry & Clay Tile Chimneys Mid-Efficiency Heating Appliances New Vent Requirements Single-Wall Metal Pipe Chimneys Vents Three-Sided Chimneys: Problems Transite Pipe Chimneys & Flues CO2 TOXICITY COALSTOVE SAFETY COMBUSTION GASES & PARTICLE HAZARDS COMBUSTION PRODUCTS & IAQ COMPLETE COMBUSTION, Stoichiometric Dead End Chimney Flue Hazards Definitions of Chimney Types & Parts DRAFT HOODS - gas fired DRAFT MEASUREMENT, CHIMNEYS & FLUES DRAFT REGULATORS, DAMPERS, BOOSTERS EFFLORESCENCE, Salts & White / Brown Deposits Fire Clearances for Masonry Chimneys Fire Clearances for Metal Chimneys Fire Clearances, Single-Wall Metal Flues CHIMNEY HEIGHT & CLEARANCE CODE Reduction in Fire Clearance - Heat Shields Single Wall Metal Flues - Oil fired heaters Single Wall Metal Pipe Flues - Gas heaters Wood & Coal Stove Flues Fire Clearance Safety Hazards, other FIREPLACES & HEARTHS Chimney Cleanout Combustible Clearance Chimney Cleanouts Required Chimney / Fireplace Settlement Chimney / Fireplace Support Repair Creosote Deposits - Fire Hazard Dead End Flues / Dead Base Chimney Hazards Fireplace Damper Trouble Fireplace Fire Hazards: Carpeting Fireplace Hearth Size Fireplace Inserts Fireplace Inspections Fireplace & Woodstove Air Contaminants Inaccessible Connections Fireplace or Woodstove Wood Burning Fireplace Roof Clearance Fire stopping at Chimney Passage Through Floors FLAME COLOR, BLUE vs YELLOW COMBUSTION FLUE SIZE SPECIFICATIONS Flue Separation Requirements Flue Tile Damage in Chimneys Flue Vent Connectors - Boilers, Furnaces Blocked Chimney at the Flue Vent Connector Dead End Chimney Flue Hazards Extended Too Far into Chimney Joint Connections - Single Wall Metal Flues Length Limits for a Flue Vent Connector Loose, Leaky, Not Sealed, Flue Vent Connector Plastic Heater Vents Plastic Vents Goodman HTPV Recall Rusted Metal Flue Vent Connectors Slope, Proper Flue Vent Connector Fuel Changes for Heating Appliances HEATING COST FUEL & BTU Cost Table HEATING INSPECTIONS HOME HEATING SAFETY HEATING SYSTEMS Lennox SAFETY 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 Nanomaterials Hazards NOISE / SOUND DIAGNOSIS & CURE ODORS & SMELLS DIAGNOSIS & CURE ODORS FROM HEATING SYSTEMS OIL HEAT SAFETY INSPECTIONS PLASTIC HEATER VENTS Safety Recalls, Chimneys, Vents, Heaters BLUE vs YELLOW COMBUSTION FLAMES BLUERAY Recall CHIMNEYS & Flues - Asbestos Transite Goodman HTPV RECALL Lennox Furnace Manuals Lennox SAFETY WARNING PLASTIC Plexvent / Ultravent RECALL Weil McLain RECALL Shared Chimney & Shared Flue Hazards Shared Chimney Flue Examples Exceptions: Shared Flues Permitted? Wood & Oil Fired Heaters Two Gas Fired Appliances Vent in One Flue Multiple Fireplaces Sharing One Flue STAIN DIAGNOSIS on BUILDING EXTERIORS Stains on chimneys Three-Sided Chimneys: Problems Transite Pipe Chimneys & Flues UNLINED FLUE INSPECTIONS WOOD, COAL STOVES & FIREPLACES Chimney Clearance & Condition Safety Coalstove Safety Creosote Deposits - Fire Hazard Dead End Flues - Dead Base Chimney Hazards Fire Clearance Safety Hazards Fire Clearance Wood & Coal Stove Flues Fire stopping at Chimney Passage Through Floors FIREPLACES & HEARTHS Fireplace Inserts Fireplace Inspections Fireplace & Woodstove Air Contaminants HEATING COST FUEL & BTU Cost Table Inaccessible Connections Fireplace or Woodstove WOOD STOVE SAFETY More Information |
This article describes chimney top repairs for masonry chimneys and clay flue tiles, work performed at or from the rooftop. This website provides 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. © Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website. Our photo above shows an unsafe chimney that was still in active use. Notice those missing bricks and lost mortar? Damaged chimney top masonry such as missing bricks and a missing chimney cap were easily spotted from ground level, raising a critical concern for the fire and gas-leak safety of the clay flue tiles lining this chimney. At the front left corner of the clay chimney flue tile you can see our pen inserted into an opening between the chimney flue tile and the (damaged) surrounding brick and concrete chimney structure - water entering the chimney structure at this location risks freeze damage to the chimney flue itself, resulting in potentially very dangerous conditions. Repair of Damaged Clay Chimney Flue Liners at the RooftopDetermine the Extent of Chimney Damage and the Safety of the Entire Chimney Flue
First, you will want to be absolutely sure that the chimney damage, whether to the ceramic clay flue liner or to the surrounding masonry or both, is limited to the upper, visible, accessible part of the chimney. Our chimney clay flue tile liner damage photos above show enough wear and cracking (above left) and opening between clay flue tile liner sections (above right) that further inspection and repair by a chimney professional is warranted. Other chimney damage lower in the chimney itself as it passes through or alongside the building could be very dangerous, even fatal if carbon monoxide or other flue gases leak into the building or if sparks cause a fire.
Our photos above show damage to the chimney clay flue tiles near the chimney top, with multiple cracks in the clay flue liner (above left), and severe spalling in the clay flue tile liner (above right) -these are two different chimneys. Both need repair. The right hand chimney (above right) may need a complete re-lining while the chimney at above left might be damaged only above the roof line, making roof top repair a reasonable approach. We suggest that you hire a professional chimney sweep who can examine the entire chimney flue. Most chimney sweeps also offer repair services, and can suggest what repairs are needed and give alternatives for the particular chimney and flue on your building. Reline the Chimney versus Repairs Just at the Chimney Top
Some chimney repair contractors will want to reline the whole chimney flue - an approach that is often safe, quick, easy, and profitable. But this approach may be inappropriate if the damage is just due to weather at the chimney top and the rest of the flue is intact and safe. Water leaking between the flue liner and the masonry surround is also a very common cause of water and frost damage at the chimney top. Most often we see spalling flue liners and loose or damaged bricks or concrete block around a chimney top caused in large part by failure to protect the chimney to from the weather; lack of an allowance for thermal movement among chimney parts, especially the liner and the surrounding masonry,can also crack and break the flue liner, especially on the above-roof portion where the chimney is in northern climates exposed to coldest temperatures. Potentially, damage to the masonry chimney structure as well as to its clay flue tile liner can occur also inside a freezing attic space. If the damage is just at the top of the chimney and its masonry flue liner, repairs can usually be completed entirely from outside, working from the rooftop. (Be sure the mason performing the repairs protects the surrounding roof surface from damage lest your chimney repair be followed by roof leaks.) Other Chimney Top Repairs for Damaged Flue Liners or Surrounding MasonrySome people try patching the damaged areas of the chimney top or chimney flue with refractory cement but we don't recommend applying "patches" to the interior of a chimney flue: there is a risk that the "patch" might later fall into and block the flue - a very dangerous condition. A better approach and the one used by most chimney repair masons who are not going to simply reline the flue, is to remove all of the damaged materials down to sound chimney flue liner and brick or block, then rebuild with new clay flue liner and brick (or block), adding an appropriate chimney cap and top seal.
Using solid masonry between the clay liner and the surrounding masonry at the chimney top is a common practice (photo at left), and having inspected quite a few chimney tops, we can't say that every chimney built this way fails, but it is not the best practice and is not recommended by experts. Our chimney top photo (left) shows that this roof top chimney seal is already cracking, threatening future damage to the chimney flue liner as well as the chimney structure at roof top. Other problems at this chimney top include the termination of both flues at the same height, and the absence of any rain cap.
Carson Dunlop's sketch (left) show some details of good chimney cap construction. The object of these details is to avoid water and frost damage to the flue or to the chimney itself. see Chimney Inspection From Outside - Rooftop for these chimney top inspection and final repair and sealing details. Questions & Answers regarding this article. Ask a Question or Search InspectAPediaHTML Comment Box is loading comments...
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