Zero clearance gas fireplace (C) Daniel FriedmanFactory-built fireplace inspection procedures
Checklist for building inspectors

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How to inspect factory-built fireplaces & fireplace inserts. This article provides a checklist useful for building or home inspectors who need to examine a factory-built fireplace and chimney.

Zero-clearance fireplaces are typically steel constructed fireplaces to burn wood or perhaps other fuels such as LP or natural gas in modern homes, usually connected to a metal chimney.

Our photo (left) shows a zero-clearance gas fireplace. Other zero clearance fireplaces burn wood or perhaps other fuels.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Factory-built fireplace inspection checklist

Zero clearance metal fireplace (C) Daniel Friedman

Following this example of hard-to-spot but unsafe factory-built fireplace installation fire hazards we provide a checklist for the inspection of factory-built fireplaces.

Watch out: we have found a few zero-clearance fireplaces improperly installed too close to combustibles.

[Click to enlarge any image]

The clearance to combustibles is not "zero" but one or more inches, depending on the materials, construction, and manufacturers' instructions.

The installer did not understand the purpose of steel clearance-assuring projections welded to the zero-clearance fireplace, and s/he had hammered them flat to "shoe-horn" the zero clearance fireplace into a too-small wood-framed rough opening.

The result was a serious building fire hazard and a building code violation as well.

Our photo of a zero-clearance fireplace from inside the framed opening (left) shows the clearance guards intact next to our ruler. But inspection showed chimney leaks onto this unit - evidenced by the rust and white stains that can ultimately damage the flue (at upper right) and the fireplace unit, making it unsafe.

Factory-built fireplace inspection checklist warning: This factory-built fireplace inspection checklist given below is a companion to our FIREPLACE INSPECTIONS article and our FIREPLACE INSPECTION PRE-FAB article

It is essential to also review and be familiar with the fireplace manufacturer's installation instructions and the homeowner should be familiar with the manufacturer's fireplace operation and maintenance instructions and recommendations.

This inspection checklist is also not a substitute for checks for compliance with local building and fire codes.

No checklist is ever a complete guide to building inspection or diagnosis since no checklist can contain every possible hazard or every clue that suggests a problem.

Therefore do not rely on this or any checklist to assure that your inspection of a chimney is complete. Instead, use this list to suggest additional topics that you otherwise may have omitted from your inspection.

The more detailed chimney inspection and repair articles at the links at Related Links and the citations below below suggest further, more-detailed chimney inspection points and procedures.

Factory-Built Fireplace, Fireplace-Insert & "Zero-Clearance Fireplace" Defects & , Unsafe Conditions
Item # OK?
Factory-built Fireplace Hazard or Concern Comment / More Detail

Building ID & Location: __________________________________________

Date & Time: _________________________________________________

Inspector: ____________________________________________________



Chimney cap and crown defects: 

missing chimney cap, damaged chimney crown or top seal, leaks into the chimney leading to rust damage on metal flues or frost and water damage to masonry flues, leading to an unsafe chimney.

Watch out: attaching anything other than the manufacturer's spark arrester to the chimney top cover and flashing violates the listing and the building code.




Chimney Chase:

Chase termination adapters and sections may be described in separate instructions from those provided with the chimney & firebox.

Inspect the chimney chase interior (it may be necessary to make or provide visual access, often feasible from inside the building attic).

Check the chimney chase interior surfaces for signs of flue or metal chimney leaks, soot, smoke, or darkening of surfaces that may indicate overheating or an usafe chimney.

if there has been a prior chimney fire in a metal flue the system should not be used again before it is replaced.

Baird (1991) reported that "certain chase termination-adapter kits were improperly installed, ... leaving a gap in the metal chimney near the top of the chase". [4]


Definition of pyrolysis


Chimney Chase insulation

does the manufacturer require or prohibit insulation within the chimney chase? Have those instructions been followed?

Note: insulation may be required or prohibited as may fire-blocking within the chimney chase. See the separate chimney chase inspection article cited at right.



Chimney elbows, bends, angles

no section of the chimney should be angled or inclined more than 30 degrees off of vertical;

where chimney elbows or angled runs are used, the weight of the chimney must be adequately supported above the elbows (by elbow support straps or by other means specified by the manufacturer).

    Chimney Installation air space / clearances: is the manufacturer-required air space or clearance provided between the chimney and any combustible materials at all locations?




Chimney passage through building interior living space: is the chimney enclosed where it passes through occupied space in the building?

Are any required fire-stopping materials (fire-sealant, fire stops) installed where the chimney passes through floors or ceilings in the building?




Chimney section connections,

connections, gaps, offsets: are connecting chimney sections adequately overlapped, connected, supported?

Baird (1991) reported that "... chimney sections are sometimes terminated at an elevation that does not allow for sufficient overlap of the various adapters and telescoping sections.

This lap distance is specified by the manufacturer.

If chimney offsets are used and not properly supported, the chimney is more likely to settle and open a gap in the flue.". [4]

    Chimney top clearances:

is the top termination of the chimney at least 3-ft. above the roof surface & 2-ft above any component of any structure that is within 10-ft. horizontal distance?

Chimney top housing, covering, shroud: have the chimney top housing or termination assembly been installed and secured following the manufacturer's instructions?

Also see Decorative Shrouds in the checklist below.


Code compliance:

are components listed and labeled and installed according to the manufacturer's installation instructions and in accordance with local building codes for use of materials, clearances, etc.?

Watch out: only the local building official has authority to declare an installation "legal" or "code-compliant".

The local code official should not approve an installation or component if the manufacturer has not provided a listing (such as UL listing) for the the component as installed and used at a particular building or site.


Component Labels:

do all parts of the pre-fabricated fireplace & chimney bear labels identifying them as listed components intended for use with the fireplace model installed?

Watch out: Baird (1991) points out that some component labels will not be visible after fireplace or chimney construction & installation are completed and must have been inspected at rough-in or other appropriate times. [4]

    Creosote or heavy soot in chimneys:

a possible chimney fire hazard, especially at wood-burning fireplaces or woodstove flues



    Decorative shroud not listed: installation of a non-listed decorative chimney top shroud [4] 



Decorative shroud connected to wood:

a decorative shroud fastened to flashing that is in contact with combustible materials (wood chimney chase materials, roofing &c) is a common cause of fires [4]

Watch out: If the decorative cap on your chimney is not listed and approved and correctly installed, have it removed, leaving the chimney flue top cap and spark arrestor installed.


Doors to the fireplace insert

If a glass fireplace door or cover has been added to the original installation, is the fireplace rated-for and does the manufacturer permit the installation of add-on glass doors?

Add-on doors can make some fireplaces operate at a higher temperature than that for which the unit was designed.

Baird (1991) reported that "... glass doors had been installed on a fireplace that had never been tested for use with glass doors". [4]

    Fireplace air circulating louvers & openings: are the air openings or louvers intended for circulating air around the fire-box clear of obstructions?  
    Fire clearances 

unsafe between metal flues or other types of chimneys and nearby combustibles.





Fireplace insert clearance to combustible materials

in accordance with both manufacturer's instructions and building codes.

Note: Baird (1991) reported that numerous fires occurred as a result of long-term effects of placing wood-framing too close to the opening of the fireplace.

"A number of fires have occurred in a single development several years after prefabricated concrete tilt-up fireplaces were installed in violation of Section 3703 (h) of the Uniform Building Code™.".. [4]

    Fireplace inserts for wood or coal installed into an existing masonry flue 

without chimney inspection and if needed, re-lining.

Fireplace hearth extension:

is the hearth extension made of only non-combustible materials?

Are the thickness, depth, width of the hearth extension in compliance with both the manufacturer's installation requirements & building codes?

Is the hearth extension also pre-fabricated and is it a listed accessory approved by the fireplace manufacturer?

[Watch for wood trim that returns around a hearth extension and terminates in contact with the fire box.]


Fireplace insert add-ons:

no add-on fireplace insert should be installed unless it is listed by a testing laboratory as approved for use with the fireplace brand and model installed in the building.

    Fireplace instructions:

the manufacturer's instructions for maintenance & use of the fireplace should be left where it will be available to building occupants.

Fireplace parts:

Are all parts of the fireplace installed in accordance with the manufacturer's instructions including connections and clearances from combustibles?

Are all parts of the fireplace un-damaged & un-modified?

Have fire clearance spacers been bent, cut, modified? Are there material intrusions into the fireplace space that violate the clearance distances intended by the spacers?

Note: Baird (1991) reported that all of the fires associated with factory-built fireplaces that he studied (n=4) were related to installation errors.. [4]

And in the article introductory text above we describe finding a fireplace insert whose welded-on extensions intended to assure adequate clearance from wood combustibles had been hammered-flat by the installer so that he could force the fireplace into a too-small wood-framed enclosure - DF.


Fireplace support:

is the fireplace adequately supported? Are there signs of tilting, settlement, movement, gaps?


Fireplace mantel & trim:

are all trim components around the face of the fireplace or applied to the actual face of the fire-box in compliance with the fireplace manufacturer's instructions & building codes?

Are there gaps or cracks between the trim and the fireplace? Are these gaps due to error or movement?

Are the fireplace mantel and trim around the fireplace hearth front at the required distance from the fireplace hearth front opening as required by the manufacturer's instructions & local building code?


Fuel used in fireplace:

most fireplace manufacturers do not permit use of manufactured "fireplace logs" made of compressed sawdust, wax-treated wood scraps, or similar products.

Fuel quantity used in fireplace:

don't build too big a fire, regardless of fuel type used. Piling on logs to make a huge bonfire in any fireplace is inviting a hazard of overheating and a building fire.

Watch out: the author's NY home [DF] caught fire in 1969 as a result of the combination of an improperly-constructed masonry fireplace (wood damper support left in place, in contact with wood wall framing, burned through) and the use of a wax log.

After the wax log had been ignited, visitors enjoyed poking at the log with a fireplace poker.

The log fell apart, suddenly and greatly increasing the level of combustion and heat in the fireplace, setting the wall above the hearth on fire.


Maintenance history:
fireplaces and in particular also fireplace chimneys require periodic cleaning, maintenance, inspection in order to avoid a chimney fire.

Note: The fireplace and chimney manufacturers recommend cleaning procedures and minimum inspection and cleaning interval.

The actual required chimney cleaning interval will vary depending on the types fo fuel used, how the fireplace is used (combustion heat for example), and the amount of fireplace usage.


Rusted or damaged chimney or fireplace components:

rusted, damaged, inoperative or missing fireplace dampers.

Examples include a damper that has rusted through, a metal damper enclosure in the chimney throat rusted through, a metal fireplace insert rusted out at the chimney base.

Watch out: damaged, leaky gas fireplace vents or flues or other fireplace components risk more than a building fire, also risking fatal carbon monoxide poisoning




Notes to the table above

Adapted from fireplace and chimney inspection safety sources including these documents

Continue reading at FIREPLACE INSPECTION PRE-FAB or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

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