Drywood termite fumigation is the most effective way to eliminate an entire drywood termite infestation from a home, especially when colonies are hidden inside walls, attics, or other inaccessible areas. The process involves sealing your house under a large tarp and filling it with a gas that penetrates every crack, crevice, and pore in the wood. For an average-sized home, it costs $1 to $4 per square foot, or roughly $2,000 to $8,000 total.
Signs You May Need Fumigation
Drywood termites live entirely inside the wood they eat, so infestations can grow for years before you notice anything. The most reliable sign is frass: tiny fecal pellets about the size of a grain of sand, hard and dry, with six concave sides that give them a hexagonal shape under magnification. Their color ranges from light tan to dark brown depending on the type of wood being consumed. You’ll typically find small piles of these pellets on windowsills, countertops, floors, or beneath infested wood, where they’ve been pushed out through tiny “kick-out holes” the termites use to keep their tunnels clean.
Other signs include:
- Small holes in wood surfaces, which serve as entry or exit points for the colony
- Discarded wings near windowsills, doors, or light fixtures, shed by reproductive swarmers during mating season
- Hollow-sounding wood when you tap on beams, frames, or furniture
- Visible damage to wooden structures, especially in attic framing or exposed beams
Finding large numbers of shed wings indoors is a particularly strong indicator that an active colony is living somewhere inside the structure. Drywood termite swarmers are distinguishable from other flying insects by their straight, bead-like antennae, broad waist with no pinched section, and two pairs of equal-length wings with a distinctive vein pattern.
Why Fumigation Instead of Spot Treatment
All drywood termite treatments fall into two categories: whole-structure or localized. A spot treatment targets a single board or small group of boards where termites have been detected. Fumigation treats the entire structure at once, reaching every infestation simultaneously, including ones you don’t know about.
That distinction matters because current detection methods are unreliable enough that you can never be completely sure where all the colony boundaries are inside a home. Spot treatments only work on infestations you’ve found. Fumigation eliminates hidden colonies in wall voids, roof framing, and other places no inspector can easily reach. For homes with multiple infestation sites or evidence of widespread activity, fumigation is the standard recommendation because it’s the only method that isn’t detection-dependent.
Spot treatments still have a role for small, clearly isolated infestations caught early. Drywood termite treatment costs for localized approaches range from $225 to $2,500 or more, depending on the scope. But if there’s any doubt about whether you’ve found everything, whole-structure fumigation is the more reliable choice.
How the Fumigation Process Works
The gas used in structural fumigation is sulfuryl fluoride, a colorless, odorless compound that’s highly toxic to insects. Inside a termite’s body, it breaks down into fluoride, which disrupts the insect’s ability to metabolize stored fats and carbohydrates. Cut off from its primary energy source, the termite tries to burn protein and amino acids instead, but can’t keep up metabolically. It dies.
During fumigation, concentrations inside single-family homes typically range from 1,440 to 3,850 parts per million. The gas penetrates deep into wood grain, reaching termites in galleries that no liquid or foam treatment could access.
The Tenting Timeline
The entire process usually takes two to three days from start to finish. Here’s what happens:
First, a pest control crew covers your entire home in heavy tarps, sealing it as tightly as possible to trap the gas inside. Warning signs are posted around the property, and the structure is secured to prevent anyone from entering. Before releasing the fumigant, applicators introduce chloropicrin, a highly irritating tear gas agent, as a safety warning. Because sulfuryl fluoride itself has no smell, chloropicrin ensures that anyone who accidentally approaches the structure will be driven away immediately.
The fumigant is then released and held inside the sealed structure for a set exposure period, typically 24 to 72 hours depending on the size of the home, the severity of the infestation, and outdoor temperatures. Warmer conditions generally allow faster penetration.
After the exposure period, the tarps are removed and industrial fans are used to aerate the structure, pushing the gas out into the atmosphere where it dissipates. Applicators then conduct air monitoring to confirm that sulfuryl fluoride levels have dropped below the EPA’s established limit of 1 part per million. You are not allowed to re-enter your home until those clearance checks are complete.
How to Prepare Your Home
Preparing for fumigation takes real effort, and your pest control company will give you a detailed checklist. The major tasks involve protecting anything you’ll consume or put on your body.
All food, medicine, vitamins, and supplements need to be either removed from the house or sealed in special protective bags (called Nylofume bags) that the fumigation company typically provides. This includes items in your refrigerator, freezer, and pantry. Anything in a factory-sealed glass or metal container is generally considered safe, but items in plastic bags, cardboard boxes, or opened containers must be bagged or taken off-site. Pet food, tobacco products, and toothpaste fall under the same rules.
You’ll also need to remove all people, pets, and houseplants. Fish tanks need to be relocated or have their air pumps disconnected and sealed, since the gas will dissolve into the water. Indoor plants will not survive the fumigant concentration. Mattresses and pillows can stay, as the gas doesn’t leave residue on fabrics or hard surfaces once the home is properly aerated.
Exterior preparation includes trimming back landscaping that touches the house so tarps can seal flush against the foundation, turning off gas lines, and sometimes removing or protecting rooftop antennas or solar panels. Your company will walk you through what applies to your specific home.
Cost Breakdown
Gas fumigation for an average-sized home runs $1 to $4 per square foot, putting a 2,000-square-foot home in the $2,000 to $8,000 range. The wide price variation depends on your home’s size, the number of stories, roof complexity (which affects tenting difficulty), your geographic region, and the severity of the infestation.
Heat treatment, another whole-structure option, costs $1 to $3 per square foot, or roughly $2,000 to $6,000 for a 2,000-square-foot home. Heat treatment raises the interior temperature high enough to kill termites throughout the structure and doesn’t involve chemicals, but it may not penetrate as deeply into thick structural timbers as gas fumigation does.
Both whole-structure approaches are significantly more expensive than spot treatments, but they address the fundamental problem: you can’t treat what you can’t find, and drywood termites are exceptionally good at hiding.
What Fumigation Won’t Do
Fumigation kills every termite inside your home at the time of treatment, but it leaves no residual protection. The moment the gas clears, your home is just as vulnerable to a new infestation as any other untreated structure. New swarmers can fly in next season and start a fresh colony.
This is why some homeowners combine fumigation with preventive measures afterward, such as wood treatments with borate-based products that make the wood itself toxic to termites, or regular inspections to catch new activity early. The fumigation solves the immediate crisis. Ongoing prevention is a separate concern that’s worth discussing with your pest control provider once the tenting is done.
Fumigation also does nothing to repair the structural damage termites have already caused. Once the infestation is eliminated, you may need a contractor to assess whether any framing, joists, or other load-bearing wood needs reinforcement or replacement.