• 210 S State St Lake Oswego, OR 97034
  • (503) 954-0726
  • clayton@metrochimneypdx.com


Zero Clearance Fireplaces are factory built units made from sheet metal or cast iron. They are also known as prefabricated fireplaces because they come ready to install complete with instructions on how to assemble the unit and explain the framework requirements. These types of fireplaces are used by professional builders and are commonly found in many Apartments and Condominiums complexes, as well as newer home builds from the mid to late 1980’s on. Zero clearance fireplaces are so named because they are sufficiently insulated to be installed within close range of combustible materials, such as walls or wood framework, without requiring a masonry foundation. Many apartment and condominium complexes come with a one. Some come with glass doors, and some only have spark arrester screens.

zero clearance fireplace


The flue is the passageway in your fireplace that allows the smoke to rise up and out of it. The dimensions of your flue, as well as every part of your zero clearance fireplace is based on measurements that must work together. As the smoke rises up your flue, it clings to the walls of the flue as soot, thereby closing off the flue. Since the flue of a Zero Clearance Fireplace is usually an 8″ round pipe (as you can see in the picture below) that runs up the interior the wooden/brick enclosures, they will get filled up and closed down quicker than a masonry fireplace during use. Solids burn up as carbon, which we call soot, and can build upon itself to close down the interior dimension of your flue, causing it to become ineffective. But more importantly, Creosote is an inevitable by-product of burning wood, and is formed when wood smoke condenses on the inside of a cool chimney. Zero Clearance fireplaces must be cleaned yearly if used.

zero clearance fireplace liner diagram

If creosote is left unchecked and allowed to build up over a period of time, it can superheat, and turn into 3rd degree creosote. (The picture below is 3rd Degree Creosote in a masonry flue, and is provided to give a visual example)

3rd degree creosote

This is the cause of chimney fires. So having our Chimney Sweeps come out and perform a chimney cleaning not only returns your flues interior dimensions to its proper working dimensions, but if early, can stop creosote build up before it is not removable with a sweep, and other actions are needed to make sure your chimneys safe use. The good news about Zero Clearance Fireplace liners is that they are made of metal, and Creosote can not get a permanent foothold on it like they can with masonry fireplaces, which are made of bricks with pores. Cleaning them yearly will handle any creosote problem your unit may have.

When we clean a zero clearance fireplace flue, we make sure to take off 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 before cleaning

zero clearance fireplace flue after cleaning

It is also important to clean a wood stove periodically to prevent the soot build up from corroding the metal on the interior of the flue, or rusting it. Carbon, if left unchecked, will corrode everything on a molecular level. To prolong the lifespan of your flue, if you use your wood stove, have it cleaned once a year and avoid costly flue replacement.


During your zero clearance fireplace cleaning, we look at all aspects of your system to give you a Safety Inspection Report on the condition of your zero clearance fireplace unit. Any problem areas and repair recommendations will be noted on this inspection, which is also a part of your receipt. We check your installation to be sure that there are no hazards created by the stove from improper installation, and that all the parts such as the damper and clay refractory heat deflection panels are in working order. If any repairs are necessary, we will inform you in the inspection so that you can contact the manufacturer or authorized replacement part reseller for the correct replacement parts. Zero Clearance Fireplace must sent to United Laboratories for testing for each new model unit that a Manufacturer produces. When the units pass U.L. testing and are cleared for mass production, they are manufactured with a placard denoting Manufacturer, Model Number, Serial Number and Date of Manufacture that is affixed somewhere at the front of the unit. Some are silver with black, others are copper with black, but they resemble the one see in the example picture.

UL plate

These unit are tested as one unit (with liner, damper, cap and everything installed as one complete unit that makes up that model number) for safety rating and insurance purposes. If a part has gone bad, it needs to be replaced with the original Manufacturer’s Part (if available) to comply with UL testing and for insurance purposes. Only if the manufacturer is no longer in existence, or they no longer make the original replacement part can we replace it with an after market part ON SOME PARTS ONLY – Caps, chase covers, storm collars, dampers and refractory (ceramic heat shield) panels on the interior of the firebox IF AVAILABLE. If the liner has gone bad, we will tell you to contact a Wood Stove Installer for repair as the Oregon Construction Contractors Board has separated Chimney Contractors for performing repairs on wood stove and prefabricated fireplace liners.

Note – It also may take a bit of time to track down the Manufacturer as many have changed hands or sold themselves off to other larger heating companies and are hard to find. Depending on the age of the unit, some Manufactures may not stock replacement parts for that model number anymore. Some Manufactures have gone out of business but sold their existing replacement parts stock to another company and parts may only be available in the stock they have left in the warehouse. Many Manufacturers have gone out of business entirely and replacement parts of any kind are not available. At that point, only some parts may be replaced with after market parts, specifically caps, chase covers and storm collars.

If you just need us to come out to inspect your chimney, but it does not need a cleaning, there is still a service call charge for this.

Schedule a chimney cleaning appointment today for one of our chimney sweeps to come out and make 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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