A Class A chimney system—also known as an all-fuel, prefab, or factory-built chimney—is a complete system in and of itself. The pipe can pass through a house as its own separate structure. The factory-built chimney is a double wall pipe, which is made of an inner wall of stainless steel and an outer wall of either stainless steel or galvanized steel. These chimney systems are designed to vent any fuel (oil, gas, wood or coal), and they have a life expectancy of 20 to 30 years, depending on use. We encourage you to keep reading to determine if a prefab chimney is right for you and your home!

Prefab Chimney Diagram - Asheville NC - Environmental Chimney

Installation Considerations

If the chimney is being used as an exterior chimney, the stainless steel outer wall is recommended. In between the two layers is a one-inch layer of insulation. This added layer reduces the clearances to a mere two inches. This means that the pipe can be installed in the middle of your house with ease. It can also be enclosed with a wooden chase that’s finished off with a chase cover made from a material of your choosing.

The particular type of all-fuel chimney you need varies depending on the size of your appliance. Improperly sized chimneys will result in a poor drafting appliance as well as increased amounts of creosote deposits; both of these scenarios put your home and family at an increased risk for both chimney fire and/or CO poisoning.


Class A chimney systems have increased in popularity since it came on the market in the 1980s, in part because of their low cost to construct and maintain as compared to a traditional masonry chimney.

Care and Maintenance

The same fire safety precautions that are used for a traditional masonry chimney should be observed where a factory-built chimney is in use as well. In order to ensure safe and optimal operation of the heating system, normal maintenance and cleaning are required, similar to those used for a traditional system. It is important to remember that the presence of water (moisture) will cause a quicker deterioration, and reduce the life exprectancy. Many chimneys may appear to be in fine condition on the outside, but the inside could be a completely different situation entirely.

We urge every homeowner to have their chimney inspected on a regular basis to keep their home and their family safe from fire hazards. The chimney should be inspected monthly during the heating season to determine if creosote has accumulated. A professional chimney sweep should be hired to clean out the unit at least once a year; however, it wouldn’t hurt to have it cleaned more frequently if the system is relied upon quite heavily.

We, the certified professionals at Environmental Chimney Service, take great pride in the work we do and endeavor to provide each of our clients a chimney that is environmentally safe for your family. If you are in the market to have a Class A/metal chimney installed (classified for wood stove or gas burning), please give us a call at your earliest convenience. We are standing by each and every day to help you with all of your chimney and dryer vent servicing needs.