Most Eastside homeowners who have a wood-burning fireplace stop using it for the same reasons: the prep work, the cleanup, the air quality restrictions during Puget Sound burn bans, and the inconsistency of actual heat output. Converting to gas eliminates all of those. The fireplace that was gathering dust becomes the one that runs every evening.
The conversion itself is less invasive than most homeowners expect — particularly for masonry fireplaces, which make up the majority of pre-1990 construction in Bellevue's established neighborhoods.
Is your wood fireplace a candidate for gas conversion?
The first question is what type of fireplace you have. Eastside homes built before roughly 1985 typically have masonry fireplaces — brick or stone firebox, concrete or stone hearth, and a masonry chimney above. These are almost always strong candidates for a gas insert conversion.
Homes built between 1985 and 2005 often have factory-built zero-clearance prefab fireplaces — a steel firebox surrounded by an air-gap chase and a lightweight metal or siding chimney exterior. These can also be converted, but the insert has to be selected to match the existing firebox dimensions and the existing chase has to be in serviceable condition.
The two situations that don't convert via insert are masonry in significant structural deterioration (deteriorated liner, failing crown, spalling brick that affects firebox integrity) and situations where the existing firebox opening dimensions don't accommodate any available insert — both rare on typical Eastside construction.
A walkthrough confirms candidacy. It's not something that can be accurately assessed remotely.
The two conversion paths
Path 1: Gas insert — the most common conversion
For masonry fireplaces, a gas insert is the standard conversion path. The insert — a sealed gas appliance — slides into the existing firebox opening. A flexible stainless co-linear liner runs from the insert's collar up through the existing chimney to a new crown termination cap. This liner becomes the dedicated vent for combustion exhaust.
What stays: the existing firebox surround, the existing hearth, and the existing masonry chimney structure. What's replaced or added: the insert itself, the stainless liner, a gas supply connection to the insert, and a face/surround update (optional, but common since the existing wood-fireplace trim often doesn't suit a gas insert's proportions).
This is the lowest-cost conversion path because it reuses the existing vent infrastructure. No new exterior penetration. No new chase framing. No roofing or flashing work above.
Path 2: New-build — when the existing firebox doesn't work
If the existing firebox is in poor condition, has dimensions that don't accommodate a modern gas insert, or if the homeowner wants to change the location or format entirely, the conversion becomes a new-build project. The existing firebox is removed or bypassed, and a new gas fireplace — typically direct-vent through an exterior wall — is installed in its place or in a new location.
This adds venting scope (new exterior penetration or new chase), but it also opens up format options that an insert conversion can't accommodate: linear wide-format units, see-through fireplaces, or a fireplace in a location with no existing chimney.
What the chimney does (and doesn't) need
For a gas insert conversion, the existing chimney doesn't need to be rebuilt or resurfaced — but it does need to be in structural condition that can support the liner installation. The chimney inspection before the liner install checks: crown condition, mortar joint integrity, flue tile condition, and any obstructions.
If the chimney inspection finds issues — a cracked liner, a failing crown, significant mortar deterioration — those items are addressed as part of the project scope. Minor issues (surface mortar, minor crown cracking) don't affect the insert conversion; significant structural deterioration does.
The liner itself is sized to the insert's venting specs. Pellet stove liners, old oil-heat liners, and other re-use scenarios aren't applicable — the gas insert gets its own dedicated co-linear stainless liner sized to the unit.
The gas line connection
A gas insert needs a gas supply connection. For most Eastside homes, there's already a gas line running to the area — to the range, the furnace, or a dryer — and a new branch can be run to the fireplace location without a full new line from the meter.
The gas line scope depends on where the nearest gas supply is relative to the fireplace location. For a living room fireplace in a typical Bellevue or Kirkland home, the run is usually short. For a finished basement or a room on the opposite side of the house from the gas meter, the run is longer. This variable affects the gas line cost line item in the estimate.
Permits for gas conversion in Bellevue
The City of Bellevue requires a gas piping permit for the new gas supply work and, in most cases, a mechanical permit for the appliance installation. These are standard permits — not unusual or difficult to pull — with fees published by Bellevue Development Services.
Prime includes permit fees in the written estimate before work starts. The permits are pulled by Prime before installation begins; inspection is scheduled and completed before the fireplace is commissioned. An unpermitted gas conversion — meaning a gas appliance connected to a gas line without a permit — will surface on home inspection at sale. The cost to remediate an unpermitted conversion is substantially higher than the permit fees.
What you won't need to do
Homeowners researching gas conversion often assume it's more invasive than it is. For a masonry fireplace with a gas insert:
- You don't need to rebuild the chimney — the existing structure stays in place.
- You don't need a new exterior wall penetration — the liner runs through the existing flue.
- You don't need to demo the existing firebox surround — though updating it is common since insert proportions differ from wood-burning proportions.
- You don't need to frame a new fireplace opening — the insert fits the existing opening.
The result: the existing masonry, hearth, and chimney cap largely stays intact. What changes is what comes out of the firebox opening and how it vents.
Thinking about converting your wood fireplace? Schedule a free walkthrough — we assess the existing firebox, confirm candidacy, and give you a written estimate with all four cost variables and permit fees included.