Zero Clearance Fireplaces often referred to as prefabricated fireplaces, are factory-built units constructed from materials like sheet metal or cast iron. They are designed for easy installation and come complete with assembly instructions and framework requirements. These fireplaces are commonly used by professional builders and are prevalent in apartment and condominium complexes, as well as newer homes constructed from the mid to late 1980s onward.


The term “zero clearance” signifies that these fireplaces are well-insulated, allowing them to be safely installed in close proximity to combustible materials like walls or wood framework, without the need for a traditional masonry foundation. Zero clearance fireplaces may vary in features, with some equipped with glass doors and others featuring spark arrester screens.

zero clearance fireplace


The flue is the passage in your fireplace responsible for allowing smoke to rise up and exit. The dimensions of your flue, as well as every component of your zero-clearance fireplace, are based on carefully coordinated measurements. As smoke ascends through your flue, it adheres to the flue walls as soot, gradually obstructing the flue’s interior.

Since the flue of a Zero Clearance Fireplace is usually an 8″ round pipe (as depicted in the picture below) that runs up the interior of wooden or brick enclosures, it tends to accumulate soot and close down more rapidly than a masonry fireplace during use. Solid particles burn as carbon, commonly known as soot, and can accumulate, diminishing the interior dimensions of your flue, rendering it less effective. More significantly, creosote is an unavoidable by-product of burning wood, forming when wood smoke condenses on the inside of a cool chimney. Zero Clearance fireplaces should undergo annual cleaning if used.

zero clearance fireplace liner diagram

If creosote is left unattended and allowed to accumulate over time, it can superheat and transform into 3rd degree creosote. (The picture below illustrates 3rd Degree Creosote in a masonry flue and is provided as a visual example.)


3rd degree creosote

This is the leading cause of chimney fires. Therefore, having our Chimney Sweeps come out to perform a chimney cleaning not only restores your flue’s interior dimensions to its proper working size but, if done early enough, can prevent creosote buildup that might become unremovable with a regular sweep, requiring additional actions to ensure the safety of your chimney. The advantage of Zero Clearance Fireplace liners is that they are made of metal, making it difficult for creosote to accumulate permanently, unlike masonry fireplaces, which are constructed from porous bricks. Cleaning them annually will effectively address any creosote issues your unit may have.


When we clean a zero-clearance fireplace flue, we ensure the removal of both soot and creosote from the fireplace pipe. Below are pictures of a Zero Clearance Fireplace flue pipe before and after cleaning.


zero clearance fireplace flue after cleaning

It is equally important to periodically clean a wood stove to prevent the buildup of soot from corroding the interior metal of the flue or causing rust. Carbon, when left unchecked, can corrode materials on a molecular level. To extend the lifespan of your flue, especially if you use your wood stove frequently, it is advisable to have it cleaned annually. This maintenance routine can help you avoid the need for costly flue replacement down the line.


During your zero clearance fireplace cleaning, we conduct a thorough examination of your system to provide you with a Safety Inspection Report detailing the condition of your zero clearance fireplace unit. This inspection includes identifying any problem areas and making repair recommendations, all of which are documented on your receipt. We also assess the installation to ensure there are no hazards resulting from improper setup and verify the functionality of essential components such as the damper and clay refractory heat deflection panels.


If any repairs are needed, we will outline them in the inspection report so that you can promptly reach out to the manufacturer or an authorized replacement part supplier to obtain the correct replacement components.


It’s worth noting that each new model of Zero Clearance Fireplace must undergo testing by United Laboratories (U.L.) for approval. Once these units pass U.L. testing and receive clearance for mass production, they are equipped with a placard that includes information such as the manufacturer, model number, serial number, and date of manufacture. This placard is affixed to the front of the unit, and its appearance may vary, but it typically resembles the example picture provided.

UL plate

These units undergo testing as a complete system (including liner, damper, cap, and all integral components) for safety certification and insurance compliance. If a part within the unit has malfunctioned, it must be replaced with the original manufacturer’s part (if available) to maintain UL (United Laboratories) certification and meet insurance requirements. Replacement with aftermarket parts is only considered for some components IF AVAILABLE, including caps, chase covers, storm collars, dampers, and refractory (ceramic heat shield) panels within the firebox.


In the event that the liner needs replacement, we will advise you to contact a Wood Stove Installer for repair. It’s important to note that the Oregon Construction Contractors Board has distinct categories for Chimney Contractors performing repairs on wood stoves and prefabricated fireplace liners.


Please be aware that tracking down the manufacturer can sometimes be a time-consuming process, especially if they have undergone changes in ownership or merged with larger heating companies. Depending on the unit’s age, some manufacturers may no longer stock replacement parts for specific model numbers. In cases where manufacturers have gone out of business but their existing replacement parts stock has been acquired by another company, parts may only be available as long as stock lasts. Unfortunately, many manufacturers have ceased operations entirely, rendering replacement parts unavailable. In such instances, only select parts, such as caps, chase covers, and storm collars, may be replaced with aftermarket alternatives.


Even if your chimney doesn’t require cleaning but you need an inspection, please note that there is still a service call charge for this service.


Schedule a chimney cleaning appointment with us today, and our experienced chimney sweeps will ensure your Zero Clearance Fireplace Unit is safe to use.



Cancelled appointments will be subject to a cancellation fee. Once you schedule the chimney cleaning, at that point you are authorizing the terms of the cancellation fee. Cancellation fee applies to people who cancel the chimney cleaning or call in to say they need to reschedule but are not actually rescheduling the appointment at that time. To not get the cancelation fee, you actually need to call up and physically reschedule the appointment time to another day/time. The charges do not apply to people who call in and actually reschedule the time.


Metro Chimney reserves the right to walk away from a job even there is signed bid before the work is initiated. If we sense there will a problem or ongoing issue between us and the customer. This is the Oregon CCB’s position. The customer can call another contractor or chimney company.





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