Adding a Fireplace to a House Without One

Decide what the fire is for

Start with the reason. A fire for atmosphere on winter evenings, a fire that actually heats a room, and a backup heat source for outages lead to different appliances.

EPA's Burn Wise guidance, now kept as a historical record, describes fireplaces as typically very inefficient heaters meant mostly for ambiance and secondary heat, and puts the share of heat most traditional open fireplaces lose up the chimney at more than 90 percent. Stoves and sealed inserts are the wood-burning choices for heat. Gas units range from mostly decorative to real room heaters. Wood, gas or electric? compares the fuels; this guide is about getting any of them into a house that has nowhere to vent.

A decision path, starting from the vent

1. Gas or wood?If you want gas, go to step 2. If you want wood or pellets, go to step 3. If you want the look with no venting, an electric unit is the answer and the rest of this guide does not apply.
2. Is there a gas supply you can extend?A gas fireplace needs a gas line to its location. If one exists nearby, a direct-vent fireplace is usually the simplest vented option. If not, a new line has to be run by a plumber or the gas company first.
3. Can a chimney rise inside or along the house?Wood fireplaces and stoves need a chimney that clears the roof by the required heights. If it can run up through closets and the attic, or in a framed chase on an outside wall, go to step 4. If neither works, a pellet stove with its own vent may be the remaining wood-type option.
4. What will the floor carry?A factory-built fireplace or a stove sits on the framed floor with the protection its manual requires. A site-built masonry fireplace and chimney need their own concrete footing, which usually means foundation work.

The options side by side

Direct-vent gas: a fire on an outside wall

A direct-vent gas fireplace is a sealed firebox that pulls combustion air from outdoors and returns its exhaust outdoors through a pipe within a pipe. Because it does not need a chimney, it is often the most practical way to add a fire to a house that has none.

The manual controls almost every detail. The Valor installation manual for one direct-vent model, as an example of what to expect, limits total vent length to 40 feet with at most four 90-degree elbows, calls for at least 24 inches of vertical rise off the unit or after the first elbow, and lists minimum distances from the outside termination to things like an operable window (12 inches), a gas meter and regulator below it (36 inches) and a mechanical air intake (72 inches). It forbids connecting the fireplace to a chimney that serves a solid-fuel appliance, requires noncombustible board around the opening, and sets a mantel clearance chart.

Those numbers belong to that model only. The point is that the wall you pick has to satisfy the manual from the inside and the outside. See direct-vent, B-vent and vent-free for how the venting types differ.

Factory-built wood fireplace: a listed system, start to finish

A factory-built wood fireplace is a metal firebox and a matching metal chimney, tested together. The building code requires these fireplaces to be listed and labeled and tested to UL 127.

A Majestic wood fireplace manual shows what that listing brings with it. The unit is listed with one chimney series and no other. The chimney needs firestop spacers at each ceiling level, a 2-inch air gap to anything combustible, and a minimum overall height that starts at 13 feet with no offsets. Its top has to clear the roof penetration by 3 feet and anything within 10 feet by 2 feet. On a combustible floor, a noncombustible hearth extension must cover a strip 16 inches deep in front of the opening, running 8 inches beyond it on both sides. It also rules out adding a wood or gas insert unless the manufacturer authorizes it in writing.

Many of these fireplaces are installed in a framed chase on an outside wall, topped by a chase cover. That chase becomes part of the house to maintain, and a rusted or poorly sealed chase cover lets water down into it. See factory-built fireplaces: care and limits and chase cover materials.

A freestanding stove instead of a fireplace

For heat, a freestanding wood stove is often the stronger choice, and it needs no built-in firebox. It sits on a protected floor, connects through stovepipe to a listed chimney, and that chimney rises through the house or along an outside wall. The building code requires factory-built chimneys serving solid-fuel appliances in homes to meet the HT requirements of UL 103. See single-wall, double-wall and Class A pipe and EPA-certified wood stoves.

Pellet stoves vent through smaller listed pipe and can often exit through a wall, but EPA notes that most of them need electricity to run. See pellet stove venting.

Building a masonry fireplace from the ground up

A site-built masonry fireplace is a structure in its own right. The 2021 IRC model text describes a footing of concrete or solid masonry no thinner than 12 inches that projects 6 inches or more past the fireplace on every side. Above it come the firebox, the smoke chamber, a lined flue, and a chimney that carries the same termination rules as any other. The flue has to be sized to the fireplace opening; for a square flue, the code's ratio method calls for a net area of at least one-tenth of the opening.

That makes a masonry fireplace the largest project on this list: foundation work, framing changes through every floor and the roof, and a design that has to work as a system. It is usually a project for an architect or designer and a mason working from the code. Related reading: chimney foundations, hearths and hearth extensions and Rumford fireplaces.

Permits, paperwork and who does what

Every vented option here involves construction permits, and the factory-built manual reviewed above tells installers to check with local building officials and obtain required permits before starting. New Jersey's chimney verification form, UCC F370, includes statements for new or additional appliances and for solid-fuel appliances and fireplaces, confirming the chimney or vent is in sound condition, free of blockage, and lined and sized for the appliance. Your construction office will tell you which subcodes and inspections apply.

Several trades usually share the work: framing and finishes, gas piping, electrical for fans or pellet stoves, roofing at the penetration, and the appliance and venting itself. We install wood stoves, fireplace inserts and gas fireplaces and gas logs, connecting gas units to a gas supply that already exists. New gas lines are outside our work. If you are weighing options, an inspection before a new appliance looks at the planned location and venting route, with findings and photos sent before anything is scheduled. See also gas fireplace installation and wood stove installation.

Questions homeowners ask

Sources

1. U.S. EPA Burn Wise: Choosing the Right Fireplace (historical page)
2. U.S. EPA Burn Wise: Choosing Wood-Burning Appliances
3. Valor 1800KN/1800KP Direct Vent Zero Clearance Gas Fireplace: Installation Manual (PDF)
4. Majestic SSTB11 Woodburning Fireplace: Installation, Operation and Maintenance Manual (PDF)
5. 2021 International Residential Code, Chapter 10: Chimneys and Fireplaces (model code text as published in the 2021 Seattle Residential Code)
6. NJ DCA Form F370: Chimney Verification for Replacement of Fuel-Fired Equipment (PDF)

This guide is general information. It can't diagnose a specific chimney; an inspection can.