Zero-Clearance Fireplaces

Our clients often ask us about adding a wood burning fireplace to an existing home. Because it involves foundation construction and a masonry chimney, adding a fireplace can be expensive. A zero-clearance wood burning fireplace, however, can be installed in almost any home, in almost any location in the home, using existing floor structures and a prefabricated chimney, minimizing much of the cost.

Zero clearance refers to a prefabricated fireplace unit that can be installed almost directly against combustible surfaces, such as walls or floors. A prefabricated chimney is then run up the inside or outside of the house.

Selecting a Zero-Clearance Fireplace

Zero-clearance fireplaces come in a variety of types. Not all types are suitable for every situation. Consult an expert before you buy and keep these considerations in mind:

  1. Where would you like to put it?

  2. Is the purpose ambiance only or do want to get some heat into the house? Most wood burning fireplaces do not actually heat the house. In fact, many cause an overall heat loss as they heat the immediate room they are in, but send all the hot air from the rest of the house racing up the chimney.

Get a Good Installer

This is not a do-it-yourself project. Enlist an expert from the beginning, ideally one trained in installing the type of system you select. The specific expertise is important because all the components must be manufacturer approved. Also, despite what the name suggests, zero-clearance fireplaces must still observe minimum clearances for safety reasons. And once installed, it is difficult to inspect the installation details – another great reason to get an expert on the job.

Glass Doors

Most zero clearance fireplaces have glass doors. In some models the glass doors can be closed while the fire is lit and in others the glass doors must be open. For example, high efficiency units are designed to operate when the glass doors are closed. Many conventional zero clearance units have glass doors to reduce heat loss when there is no fire and should be left open when the fire is lit.

Inspection Requirements

Because zero-clearance fireplaces leave less room for error due to the proximity of a combustible material, they require yearly inspection.

Many zero-clearance fireplaces are installed with a prefabricated chimney pipe enclosed in a chimney chase (enclosure running up the outside of the house). If animals get through the chimney chase, they can build nests in direct contact with the pipe. Under the right conditions, a fire could start in the chimney chase.

Creosote is a combustible deposit that builds up on the inside of a chimney flue. It must be cleaned out regularly to avoid chimney fire.

A good inspection is your best defense against chimney or house fires. The chimney and fireplace inspection industry is unlicensed and unregulated in most states and provinces. Fortunately, excellent organizations of professionals do exist. In the United States, the National Chimney Sweep Guild created a certification organization called the Chimney Safety Institute of America. Look for an inspector who is CSIA certified. In Canada, look for an inspector certified by the Wood Energy Technology Transfer Inc., or WETT certified.

General Tips

  • Burn only seasoned hardwood. Do not burn scraps of wood and paper.
  • Load the logs near the back of the fireplace. Use the spark screen.
  • Do not leave a fire unattended.
  • Make sure your smoke and CO detectors are functioning.
  • Never restrict air flow to the fireplace.
  • Do not operate the fireplace with the glass doors closed without verifying if it is certified to operate with the doors closed.
  • Keep the hearth area clear.
  • Have your chimney and fireplace inspected and cleaned yearly.


Source: Pillar To Post Information Series