Dampwood Termite Treatment Cost in 2026

The Pacific dampwood termite (Zootermopsis angusticollis) is the largest termite species in the United States. Workers reach 20 mm. The colony is also unusual in that it does not have a true worker caste; nymphs do the work and eventually mature into reproductives or soldiers. The reason this matters for cost is that the species needs wood with a moisture content above roughly 30 percent to thrive. Below 20 percent, the colony cannot survive long. Below 15 percent, it dies fast.

That moisture requirement makes dampwood the easiest US termite to control. The treatment plan is, in short, find the water source, fix it, and the termites die. Borate solutions like BoraCare and Tim-Bor are applied to the damaged wood to accelerate the kill and to make the wood unpalatable to the next colony, but most of the work is done by the building drying out. Pacific Northwest pest control operators are typically explicit about this with homeowners. A reputable operator will refuse to take payment for repeat chemical treatments if the underlying moisture problem has not been fixed, because the chemical alone will not control the infestation.

The cost decomposes into three buckets. Bucket one is the inspection, which is typically $75 to $150 and includes a moisture meter survey of the suspected area and a borescope inspection if cavity wood is involved. Bucket two is the chemical treatment of the damaged wood, $250 to $600, applied by a licensed pest control operator. Bucket three, which is usually the biggest line item, is the structural and moisture remediation, anywhere from $300 for a downspout extension to $4,500 for a full crawlspace vapor barrier replacement or a roof flashing rebuild.

The reason this site treats moisture remediation as part of the dampwood cost discussion (rather than ignoring it) is that homeowners who pay only for the chemical treatment almost always come back. Without the moisture fix, the colony reinvades the same wood or finds new wet wood within one or two wet seasons. The combined chemical + moisture cost is the realistic 10-year cost of dampwood control.

For homes in the coastal Pacific Northwest, two common moisture sources cause most dampwood activity. First, the deck ledger board where it meets the house wall. If the flashing is missing or has failed, rain runs behind the ledger and saturates the band joist for years before anyone notices. Second, the crawlspace. Pacific Northwest crawlspaces commonly run at 70 to 85 percent relative humidity in winter unless they have an intact vapor barrier and adequate ventilation. That humidity migrates into the sill plate and the band joist, which is exactly where dampwood termites set up.

Both BoraCare and Tim-Bor use disodium octaborate tetrahydrate (DOT) as the active ingredient. BoraCare is a 40 percent DOT solution in glycol carrier, formulated to penetrate solid wood when brushed or sprayed on the surface. Tim-Bor is a powder DOT formulation mixed with water for surface application or void injection. Both products are EPA-registered for wood-destroying organism control, including termites, carpenter ants, and decay fungi. The DOT mode of action is inhibition of gut metabolism in insects that consume treated cellulose.

BoraCare carries EPA Reg No. 64405-1 and the technical product information is available through Nisus Corporation's BoraCare product documentation. Tim-Bor carries EPA Reg No. 64405-8. Both are low-toxicity products that are considered safe for use in occupied structures (no vacate, no tent, no special protective equipment beyond standard PPE for the applicator). For the homeowner, the practical advantage is that treatment can be applied while the family is at home, and re-entry into the treated area is immediate after the solution dries.

The treatment protocol for a dampwood job is straightforward. The pest control operator identifies the infested members with a moisture meter (looking for 30+ percent moisture content in wood that should be 12 to 15 percent). The operator brushes or low-pressure sprays BoraCare on the exterior of the wood, drills 1/4 inch holes spaced every 18 to 24 inches along the member, and injects Tim-Bor solution into the interior. The borate diffuses through the wet cellulose over 30 to 60 days and remains in the wood for the structural life of the lumber, provided the wood does not get wet enough to leach the borate out. The dosage and application method follow the published Nisus label.

Where dampwood treatment fails, it is almost always because the borate did not reach a section of wood where the colony was still active. The common scenarios: a colony in a wall cavity behind unreachable stucco, a colony in a buried deck post that the operator could not access without demolition, or a colony in the framing of an unfinished addition that was excluded from the inspection scope. A good operator walks the entire property, not just the visible damage area, before quoting.