Fumigating for termites involves sealing your entire home under a tent and filling it with a lethal gas that penetrates every piece of wood in the structure. It’s the most effective way to eliminate drywood termites, especially when colonies are hidden behind walls where spot treatments can’t reach. The process typically costs $1 to $4 per square foot, or $2,000 to $8,000 for an average home, and requires you to leave for two to three days.
When Fumigation Is Necessary
Fumigation is primarily used against drywood termites, which nest inside the wood of your home rather than in the soil beneath it. Because these termites can establish multiple colonies behind drywall, inside attic framing, and in other concealed spaces, current detection methods can’t reliably map every infestation. You might find evidence of one colony and miss three others. That uncertainty is the main reason whole-structure fumigation exists: it treats everything at once, including colonies you don’t know about.
Subterranean termites, the other major type, live in the soil and enter your home from below. They’re typically managed with soil barriers and baiting systems rather than fumigation. If an inspector tells you that you have drywood termites in multiple locations, or that the extent of the infestation is unclear, fumigation is likely the recommendation you’ll hear.
How the Gas Kills Termites
The standard fumigation chemical is sulfuryl fluoride, a colorless, odorless gas. Once inside a termite’s body, it breaks down into fluoride, which disrupts the insect’s ability to metabolize fats and carbohydrates for energy. The termite tries to switch to protein as an alternative fuel source, but it can’t keep up with its energy demands and dies within several days. The gas reaches termites wherever they are in the structure, including deep inside wall cavities and thick structural beams that no liquid treatment could penetrate.
What Happens During the Process
A fumigation crew covers your entire home with heavy tarps, sealing the edges to the ground so gas can’t escape. Before introducing the fumigant, they release a separate warning agent (a tear gas compound) that makes it immediately obvious to anyone nearby that the structure is dangerous to enter. The fumigant itself is pumped in and held at concentration for roughly 16 to 30 hours, depending on the size of your home, the type of construction, and the outside temperature.
After the exposure period, the crew opens the structure and uses fans to aerate it for a minimum of 12 hours. They then test the air inside with monitoring equipment. You cannot re-enter until the gas concentration drops to 1 part per million or less. From start to finish, most homeowners are out of their home for two to three days.
Preparing Your Home
Before fumigation day, you’ll need to remove or double-bag all food, medicine, vitamins, and anything consumable that isn’t in a sealed glass or metal container. This includes pet food, spices, and items in your refrigerator and freezer. Plants need to come out, and all people and pets (including fish) must leave. You’ll also need to water the soil around your foundation, trim back landscaping that touches the house so tarps can be placed, and unlock all interior doors and cabinets so the gas circulates freely. Your fumigation company will give you a detailed checklist, but the food and medicine removal is the part most people underestimate in terms of time.
What to Expect After Returning
Sulfuryl fluoride doesn’t leave a residue on surfaces, so you won’t need to deep-clean countertops or furniture after returning. The gas dissipates completely during aeration. You may find dead termites dropping out of wood or accumulating near windowsills in the days and weeks following treatment, which is normal. Termites that were deep inside wood take longer to die and may not appear immediately.
One important thing to understand: fumigation kills the termites present in your home at the time of treatment, but it does not prevent new termites from entering later. There is no lasting chemical barrier left behind. If conditions that attracted drywood termites persist (exposed wood, cracks in exterior walls, unscreened attic vents), reinfestation is possible over time. Some homeowners schedule periodic inspections after fumigation to catch any new activity early.
Cost Breakdown
Gas fumigation runs $1 to $4 per square foot, putting most homes in the $2,000 to $8,000 range. The wide spread depends on your home’s size, the number of stories, how complex the roof structure is (which affects tenting difficulty), and your geographic location. Larger or multi-story homes with steep rooflines sit at the higher end. Some companies include the termite inspection in the fumigation price, while others charge separately.
If your home is part of an HOA or a condo complex, costs and logistics get more complicated because adjacent units may need to be included under the tent. Get at least two or three estimates, and confirm that the quote includes monitoring during fumigation, since monitored fumigations (where gas levels are tracked with sensors inside the structure) have the highest success rates.
Alternatives to Full Fumigation
If your infestation is limited to a small, clearly defined area, localized treatments can work. Options include injecting termiticides directly into infested wood, applying heat to specific sections (raising the wood temperature to at least 120°F for 33 minutes), using microwave devices that kill termites in individual boards, or simply replacing the damaged wood entirely. These approaches cost less and don’t require leaving your home.
The tradeoff is certainty. Because drywood termites are difficult to detect behind walls, localized treatments always carry the risk of missing a hidden colony. You might treat the infestation you can see and discover a new one six months later in a different part of the house.
Whole-structure heat treatment is the main chemical-free alternative to gas fumigation. The entire home is heated until all wood reaches at least 120°F. It costs $1 to $3 per square foot, or roughly $2,000 to $6,000 for a 2,000-square-foot home. Heat treatment avoids the use of any chemical fumigant, but it can potentially damage heat-sensitive items like electronics, candles, and certain plastics if they aren’t removed beforehand.
Choosing Between Gas and Heat
Gas fumigation with sulfuryl fluoride has the longest track record and the highest documented efficacy rates when properly monitored. It penetrates uniformly throughout the structure regardless of wall thickness or construction type. Heat treatment is effective but depends on achieving adequate temperatures in every piece of wood, which can be harder in homes with thick walls, dense insulation, or complex floor plans where heat distribution is uneven.
Both methods share the same limitation: neither leaves a residual barrier against future infestation. Your choice often comes down to whether you want to avoid chemicals (heat wins), whether your home’s construction makes even heating difficult (gas wins), and what’s available from licensed operators in your area. In either case, a monitored treatment with documented readings gives you the best assurance that every part of the structure received adequate exposure.