How a Gas Fireplace Is Installed: Steps and Costs

Last updated: October 2026

Installing a gas fireplace means choosing the type of unit, planning how it will vent, running a gas line and any electrical, setting and connecting the fireplace, installing its safety barrier, and passing a county inspection. In Fairfax County, every gas appliance installation requires a permit, even a straight replacement.

On AVS’s existing installation guides, gas fireplace installation labor runs about $600 to $1,600, gas fireplace inserts start at around $1,200, and custom installations can cost more than $4,000.

Planning a gas fireplace installation in Alexandria, Arlington, Fairfax or elsewhere in Northern Virginia? AVS’s licensed technicians install and service gas fireplaces across Northern Virginia and Maryland. Call 703-457-9028 (VA) or 301-686-7129 (MD) for an estimate.

Types of gas fireplaces and inserts

The right type depends on whether you already have a fireplace and where you want the new one.

Each type uses natural gas or propane. If your home doesn’t have a natural gas line, a propane setup is an option, and the fireplace must be configured for the fuel it will burn.

Venting options: direct vent, natural vent and vent-free

Venting is the most important and most difficult part of a gas fireplace installation. It’s what keeps combustion gases out of your living space.

Direct vent. A direct-vent fireplace uses two vents: one carries exhaust out of the home, and the other brings fresh air in for combustion. The vent can run straight out through an exterior wall or, if that’s not possible, up through the roof. Choosing the correct flue pipe size matters, both for safety and to avoid cutting unnecessary holes in the wall.

Natural vent (B-vent). These units vent vertically through a chimney or flue rather than straight out a wall.

Vent-free. These units don’t vent to the outside at all, so they’re only permitted in certain locations and situations. Learn more about the pros and cons of vent-free gas logs before choosing one.

Gas line, electrical and ignition

Gas line. The gas supply line is the main early step of a gas fireplace installation. A licensed professional decides the route and installs threaded black metal gas pipe of a type approved in your fireplace’s installation manual. In Fairfax County, adding new gas piping changes which permit you need (more on that below).

Ignition and electrical. Gas fireplaces use one of two ignition systems, and that decides whether you need an electrical connection:

According to fireplace manufacturer Heatilator, a standing pilot doesn’t need electricity to light the flame, while an intermittent pilot system requires electricity to spark the pilot each time it’s used. A blower fan also needs power, so most installations include an electrical outlet or circuit near the fireplace.

Who does what on a gas fireplace project

Step-by-step gas fireplace installation

Here’s how a professional gas fireplace installation comes together, based on AVS’s installation instructions and the manufacturer’s manual for the unit.

1. Choose the location and confirm clearances. Check the manufacturer’s required clearances from the firebox to surrounding walls, framing and the mantel.
2. Plan the gas line route. The gas fitter decides how the supply line will reach the fireplace.
3. Frame the space. Build the platform or chase that will hold the fireplace.
4. Mark the mantel location. Place the mantel to mark and cut the baseboard.
5. Set the firebox and mark the vents. Place the firebox on its legs temporarily to mark the vent holes, then drill them.
6. Route the vent. Decide whether the vent will exit through the wall or the roof, using the correct flue pipe size.
7. Fit the fire stop. Install the fire stop where the vent passes through the wall or ceiling.
8. Install the vent pipe and exterior cap. Fix the fireplace in place and make sure the external vent cap passes through to the outdoors.
9. Connect gas and electrical. Hook up the gas line and power, then leak-test the connections and run a burn test.
10. Install the barrier, surround and mantel. Fit the protective safety barrier, then finish the surround, columns and mantel shelf.
11. Pass the county inspection. The inspector verifies the installation meets code.

How long does gas fireplace installation take?

The fireplace itself can often be installed in about a day, as Family Handyman notes for a direct-vent unit, but the full project usually takes several days. Framing, gas and electrical work, finishing, and scheduling the county inspection all add time.

How much does gas fireplace installation cost in Northern Virginia?

On AVS’s existing installation guides:

What raises the price:

• A new gas line. Running gas to a room that doesn’t have it adds labor and changes the permit.
• Venting through the roof instead of straight out an exterior wall.
• Chimney relining for an insert in an older masonry fireplace.
• Electrical work for an intermittent pilot ignition or blower.
• Custom surrounds and mantels.

AVS also notes that if natural gas or electricity isn’t readily available at your home, labor costs rise. Whatever the budget, fireplace safety matters more than cost.

Permits, inspection and safety in Fairfax County

Fairfax County treats gas fireplaces like any other fuel-burning appliance:

• A permit is always required. The county’s Household Appliance (HAPL) permit covers the replacement or first-time installation of appliances in a home, and it requires one inspection. Gas appliances aren’t exempt, even for a like-for-like replacement.
• New gas piping means a different permit. If the project includes new gas piping, you need a Residential Plumbing permit instead of a Household Appliance permit.
• The vent or chimney must be certified. For replacement installations of fuel-burning appliances, Fairfax County uses a vent/chimney certification in which a certifier with a Virginia contractor’s license confirms the vent or chimney is sized to the Virginia Residential Code and is clean, unobstructed and in operable condition.
• Let your contractor pull the permit. Fairfax County strongly suggests that the contractor secure the necessary permits in their name.

The safety barrier is required. According to the Hearth, Patio & Barbecue Association, a standard effective January 1, 2015, requires technicians to install a protective barrier before leaving the home if a gas fireplace’s glass surface exceeds 172 degrees Fahrenheit. If your fireplace came with a barrier, make sure it’s installed.

Arlington, Loudoun and Prince William counties and Maryland jurisdictions set their own permit requirements, so your installer should pull the right permit for your address.

Installing an insert? Check the chimney first

A gas insert relies on the existing chimney to carry exhaust out of your home, so the chimney has to be in good condition before installation. Fairfax County’s vent and chimney certification requires the vent or chimney to be clean, free of obstructions and sized to code, and it asks whether a re-line system was installed, because many older chimneys need a new liner before an insert can vent safely. Watch for the signs that your chimney needs cleaning or repair before you schedule the work.

Gas fireplace installation in Alexandria, Arlington and across Northern Virginia

AVS installs gas fireplaces throughout Northern Virginia, including Alexandria, Arlington, Fairfax, Loudoun and Prince William counties, and in Montgomery and Prince George’s counties in Maryland. If you live in Arlington, see our local fireplace installation in Arlington page.

A few local considerations:

• Townhouses and condos. If your HOA controls exterior changes, check the rules before a vent goes through an outside wall.
• Older masonry fireplaces. An existing brick fireplace can take a gas insert or gas logs, but the chimney should be inspected first.
• Permits vary by jurisdiction. Fairfax County’s rules are described above; other counties and cities have their own process.

Why Northern Virginia homeowners choose AVS for gas fireplace installation

• Licensed, trained technicians for both gas fireplace installation and repair
• Founded in 1991, with more than 50,000 residential and commercial customers served across the Washington DC metro area
• Licensed in Virginia (HVAC 2705039269A) and Maryland (HVAC 520714137895, Home Improvement 4192876)
• 24/7 service, 365 days a year, with no extra charge for evenings, weekends or holidays
• Call 703-457-9028 (VA) or 301-686-7129 (MD)

Frequently Asked Questions

Will my gas fireplace work during a power outage?

It depends on the ignition. Heatilator explains that a fireplace with a standing pilot should light fine during a power outage, because it doesn’t need electricity to light the flame. Newer fireplaces with intermittent pilot ignition need electricity to spark the pilot, but many models include a battery backup. The blower won’t run without power.

Can I convert my wood-burning fireplace to gas?

Yes. Common options are installing gas logs in the existing firebox or installing a gas fireplace insert, which typically vents through the chimney with a liner. Either way, the chimney should be inspected first, and in Fairfax County the work needs a permit and a vent or chimney certification.

How often should a gas fireplace be inspected?

At least once a year. The Chimney Safety Institute of America follows National Fire Protection Association Standard 211, which says chimneys, fireplaces and vents should be inspected at least once a year for soundness, freedom from deposits and correct clearances. That applies to gas fireplaces, not just wood-burning ones.

Can I install a gas fireplace myself?

It’s not a DIY job. A contractor is required to install direct-vent and vent-free gas fireplaces, as Total Home Supply notes, and Fairfax County strongly suggests that a licensed contractor pull the permit. The work involves gas piping, venting and safety testing that must pass a county inspection.

How hot does gas fireplace glass get?

Very hot. In a petition to the U.S. Consumer Product Safety Commission, Consumer Reports noted that industry standards had allowed gas fireplace glass fronts to reach temperatures of 500 degrees Fahrenheit. That’s why newer fireplaces come with a protective barrier and why young children should be kept away from the glass.

Do I need a carbon monoxide detector with a gas fireplace?

Yes, it’s a smart safeguard. Gas utility Philadelphia Gas Works recommends installing a battery-operated carbon monoxide detector in homes with gas appliances. Place detectors according to the manufacturer’s instructions, test them regularly, and have the fireplace and vent inspected every year.