Adding a wood stove to your unfinished garage can make it much more comfortable in cold weather, but it's important to vent the stove correctly. Simply running the stovepipe out a window or through the wall could result in hazardous conditions. You have several options for venting a wood stove out of your garage, but all of them require a little care and planning.
Most garages are single-story structures with no attic, making it relatively simple to vent your stove through the roof. For this type of installation, the pipe runs upward from the stove and connects to an insulated chimney. You'll need a support box right below the chimney level to keep the chimney itself stable. All chimneys need to extend at least 3 feet above the surface of the roof and 2 feet higher than all parts of the building within 10 feet of the chimney itself.
Garages with slanted ceilings vent similarly to a standard roof vent, but need a few special considerations. Instead of installing a ceiling support box, you'll need to attach a bracket at the roof level. Extend the insulated chimney partly down into the garage and connect it to the stovepipe. Do not run the stovepipe up near the ceiling, since the hot pipe could create a fire hazard.
Through the Wall
When roof venting is inconvenient or impractical, a wall vent may work better. This type of stove vent involves a horizontal stovepipe running from the chimney to a hole in the garage wall. The chimney itself begins at the point where the stovepipe meets the wall. Insulate the pipe at this connection point to reduce fire hazard. This venting method results in a tall insulated chimney running up the side of the garage, which can be visually distracting. Build a wooden frame around the outside of the chimney and add stucco or siding to provide a more attractive venting option.
Never pass a stovepipe through the wall, ceiling, floor or a window. Hot pipe can set flammable materials on fire if they come into contact with it. If pipe must pass through the building, use insulated chimney pipe. For most efficient operation, choose a venting solution with few bends in it. Straight chimneys and stovepipes have a better draft and encourage the fire to burn more cleanly.