A fireplace is one of those features that feels almost universally safe — after all, fire burns things, and throwing something in seems harmless enough. But what goes into your firebox has a direct effect on air quality inside your home, the condition of your chimney liner, and your risk of a chimney fire or carbon monoxide exposure.
Florida homeowners tend to use their fireplaces seasonally and lightly, which means the fireplace may sit idle for months, then get fired up on a cool December evening without much thought about what gets tossed in. That casual relationship with the fireplace is exactly where problems start.
This guide covers the materials that should never go into a fireplace — wood-burning or gas — and explains the real reasons why, so you can make informed decisions every time you light a fire.
Key Takeaways
- Never burn treated, painted, or stained wood — the chemicals released are toxic and leave residues in your flue that standard cleaning cannot remove.
- Wet or humid wood produces excessive creosote and dramatically accelerates dangerous buildup in your chimney liner.
- Driftwood and salt-soaked wood are a Florida-specific hazard that corrodes chimney components from the inside out.
- Gas fireplaces are sealed systems — nothing should ever be placed inside them that is not manufacturer-approved.
- Carbon monoxide detectors are non-negotiable; always have working detectors before lighting any fire.
Treated, Painted, or Stained Wood
This is the most common mistake homeowners make, and one of the most dangerous. Pressure-treated lumber — the greenish wood used in decks, fences, and outdoor structures — is saturated with chemical preservatives designed to resist rot and insects. When burned, those chemicals release toxic compounds including heavy metals and other harmful residues.
Painted or stained wood presents the same problem. The combustion temperature inside a firebox is nowhere near high enough to cleanly neutralize those compounds. Instead, they off-gas into your living space and coat the interior of your flue with residues that standard chimney cleaning does not fully remove.
In Florida, treated lumber is everywhere — old fence boards, deck scraps, pressure-treated framing from storm repairs. It often ends up in a woodpile without a second thought. If you are not certain the wood is untreated, do not burn it.
Wet or Unseasoned Wood
Seasoned firewood has been dried for at least six months to a year, bringing its moisture content down to around 20 percent or less. Wet or green wood — freshly cut or improperly stored — can have moisture content above 50 percent.
When you burn wet wood, a significant portion of the fire's energy goes toward boiling off that moisture rather than producing heat. The result is a cooler, smokier fire that produces far more creosote — a flammable, tar-like byproduct that accumulates inside your flue. The CSIA recommends a chimney inspection when creosote deposits reach 1/8 inch, and wet wood gets you there much faster.
This is particularly relevant in Florida. The humidity here is relentless, and wood stored outdoors without proper cover can re-absorb moisture even after it was initially well-seasoned. Store your firewood elevated off the ground, covered on top but open on the sides, and away from the exterior wall of your home.
Cardboard, Packaging Materials, and Household Trash
Cardboard burns too fast. Large pieces can send flaming embers up the flue and out the top of the chimney, landing on your roof or nearby vegetation. In Florida's dry winter months, when lawns and landscaping can get parched, this is a genuine fire hazard.
Colored or glossy paper — including gift wrap, magazine pages, and printed cardboard — contains inks and coatings that release toxic fumes when burned. Plastic packaging, foam, and anything with a plastic coating should never go near an open flame indoors. These materials produce dense, dark smoke loaded with compounds that are harmful to breathe and leave residues in the flue that no standard cleaning removes.
Beyond the health risk, burning household waste in a residential fireplace is prohibited under Florida state law and local ordinances in most jurisdictions. The fireplace is a heating appliance, not a disposal system.
Driftwood and Salt-Soaked Wood
Living on or near the Florida coast comes with easy access to driftwood, and it can look appealingly rustic in a fireplace. Do not burn it. Wood that has soaked in saltwater for any length of time is saturated with sodium chloride and other minerals. When burned, it releases corrosive compounds that attack metal fireplace components and chimney liners.
Salt air alone — without direct saltwater exposure — accelerates corrosion on chimney caps, dampers, and flashing over time. Burning salt-laden wood accelerates that damage dramatically from the inside. For coastal homeowners, chimney maintenance is already more frequent due to salt air exposure. Adding salt-soaked fuel to the fire only shortens the lifespan of your system further.
Accelerants and Lighter Fluid
Gasoline, lighter fluid, charcoal starter, and other liquid accelerants have no place in a wood-burning fireplace. They can cause sudden explosive flare-ups that send flames into areas of the firebox not designed to handle them, including the damper, smoke shelf, and lower flue. The surge in heat can crack fireplace components or overwhelm a system already operating near its thermal limits.
If your wood is properly seasoned and your fire-starting technique is sound — small kindling, good draft, the damper fully open before striking a match — you should not need accelerants. Commercially made fire starters, the wax-and-sawdust variety, are a safe and effective alternative.
Anything Inside a Gas Fireplace
Gas fireplaces are common throughout Florida, and they are a fundamentally different appliance than a wood-burning firebox. The burner, logs, and media inside a gas fireplace are engineered components — the ceramic or refractory logs are positioned specifically to produce the correct flame pattern and direct heat safely.
Placing real wood, paper, decorative items, or anything else inside a gas fireplace is dangerous. It can block the burner, disrupt gas flow, create combustion byproducts the venting system was not designed to handle, and in some cases cause a fire outside the firebox itself. Treat the interior of a gas fireplace as a sealed system. Nothing goes in, nothing gets moved around.
If you want to add visual interest, use only items the manufacturer explicitly states are compatible with your specific unit — and even then, confirm with a fireplace professional before making changes.
A Note on Florida Firewood and Carbon Monoxide Safety
Florida has its own wood landscape. Live oak is one of the best burning hardwoods available locally — dense, long-burning, and widely available. Slash pine and other Florida pines burn hot but produce more creosote and sap, so they are better used as kindling than as a primary fuel. Avoid burning any wood from citrus trees that may have been treated with pesticides.
Whatever wood you use, source it locally where possible. Transporting firewood across county or state lines can introduce invasive insects — a real concern that Florida agricultural authorities take seriously.
Carbon monoxide is the invisible risk that runs through nearly all of these scenarios. CO is odorless and colorless, and exposure builds gradually. If your home does not have working carbon monoxide detectors, that is the first thing to address — before the next fire, regardless of what you are burning.