Borate Wood Treatment for Termites

Borate wood treatments, sold under names like Bora-Care and Tim-bor, protect bare wood from termites by soaking a borate salt (disodium octaborate tetrahydrate) into the wood itself. Termites that chew treated wood ingest the borate and die, and the wood stops being food. Borates are most useful on new construction framing before drywall goes up, on exposed wood in crawl spaces, attics and basements, and as a spot treatment for drywood termites and wood-boring beetles. They are not a soil barrier, they cannot soak through paint or sealer, and they wash out of wood that stays wet or exposed to rain. For an active subterranean termite infestation, they are a supplement to soil treatment or baits, not a replacement.

Part of our Pest Control guide →

In this guide

1. How Borate Treatments Work
2. Bora-Care vs Tim-bor
3. Where Borate Treatment Is Used
4. Where Borates Do Not Work Well
5. How Borate Treatments Are Applied
6. Borate-Treated Lumber vs Field-Applied Borates
7. DIY or Hire a Pro?
8. How Long Does Borate Protection Last?
9. Borates in a Complete Termite Plan
10. Frequently Asked Questions

How Borate Treatments Work

Borates are salts of boron, the same family of minerals as borax. Dissolved in water, they move into wood by diffusion, following moisture into the fibers. Once inside, the borate stays put as long as the wood stays reasonably dry. When termites, carpenter ants or wood-boring beetle larvae eat treated wood, the borate disrupts their digestion and metabolism, and they starve or die. Borates also inhibit the fungi that cause wood rot. For how borates fit alongside other termite and household pest methods, see our pest control guide.

Borates have relatively low toxicity to people and pets compared with many traditional wood preservatives and termiticides, which is a big reason they became popular for indoor framing. That does not make them harmless. Read and follow the label, wear the protective equipment it lists, and keep children and pets away from wet treated surfaces.

Bora-Care vs Tim-bor

Feature	Bora-Care	Tim-bor
Form	Liquid concentrate with glycols	Water-soluble powder
Active ingredient	Disodium octaborate tetrahydrate	Disodium octaborate tetrahydrate
Mixing	Diluted with water per label (commonly 1:1)	Dissolved in water to the label’s percentage
Penetration aid	Glycols help carry borate deeper, especially in drier wood	Relies on water diffusion
Typical uses	Framing, logs, crawl spaces, pre-construction termite protection	Framing, crawl spaces, attics, spot treatment, foams and dusts
Handling	Thick concentrate; mix thoroughly	Easy to measure; dissolves best in warm water

Both use the same borate compound. The main practical difference is the glycol in Bora-Care, which the manufacturer says improves penetration into dry wood. Tim-bor is often favored for its flexibility, since the same powder can be mixed as a spray or used as a dust. Professional pest control companies use both, and some sell their own borate brands. Product labels and registrations differ by state, so check that the product you buy is labeled for your intended use.

Where Borate Treatment Is Used

New construction and remodels

The best time to treat is when framing is bare: after the house is dried in and before insulation and drywall. Sill plates, studs, joists and sheathing within a few feet of the foundation are the priority, because subterranean termites usually enter from the soil. Some borate products are labeled as pre-construction termite treatments when applied to framing as directed, which builders use in place of or alongside soil treatment. Requirements vary by local code and lender, so builders should confirm what is accepted.

Crawl spaces, basements and attics

In existing homes, any wood you can reach that is bare can be treated: floor joists and subfloor in crawl spaces, basement sill plates and rim joists, and attic rafters. Treating crawl space wood is one of the most common borate jobs, because it also protects against decay in a damp area.

Drywood termites and wood-boring beetles

Drywood termites, common in the coastal South, Southwest and California, live entirely inside the wood they eat. Borates are useful for localized drywood infestations in accessible wood, often injected into drilled holes or applied as a foam. Powderpost beetles, which leave small round exit holes and fine powdery frass, are also controlled by borate treatment of bare wood. Widespread drywood infestations in inaccessible areas usually call for whole-structure fumigation instead; our guide on preparing for termite tenting covers that process.

Log homes and outbuildings

Log homes, timber frames, sheds and barns are often treated with borates before staining and sealing, then protected with a water-repellent finish to keep the borate from leaching.

Where Borates Do Not Work Well

• Painted, stained, sealed or varnished wood. The borate cannot get in. You must strip finishes or drill and inject.
• Wood exposed to rain or in contact with soil. Borates are water-soluble and leach out. Exterior trim, deck boards and fence posts need pressure-treated lumber or a sealed borate treatment.
• Soil. Borates do not create a chemical barrier in the ground. Subterranean termites can still build mud tubes over treated wood to reach untreated wood.
• Inaccessible framing. Wood behind finished drywall cannot be sprayed without opening walls, though foams can be injected into wall voids in some situations.
• Large active infestations. Borates protect wood and kill termites that feed on it, but they do not eliminate a whole subterranean colony living in the soil.

How Borate Treatments Are Applied

Application details depend on the product label, which is a legal document, so read it in full. A typical DIY application on bare framing in a crawl space looks like this:

1. Inspect first. Look for mud tubes, damaged wood, frass and moisture problems. Our guide to signs of termites shows what to look for.
2. Fix moisture. Repair leaks, improve crawl space ventilation or vapor barriers, and keep wood dry. Borates work best in wood that stays dry, and termites favor damp wood.
3. Clean the surface. Brush off dirt, dust and cobwebs so the solution contacts bare wood.
4. Mix the solution exactly as the label directs, using warm water for powders.
5. Apply with a low-pressure pump sprayer or brush until the wood surface is wet but not dripping heavily. Labels often call for more than one coat on thicker lumber, letting the wood absorb between coats.
6. Let it dry and keep the treated wood protected from rain. The solution may leave a light white residue.

Wear gloves, eye protection and long sleeves, and use respiratory protection in confined spaces as the label directs. Ventilate crawl spaces and attics well while working.

Borate-Treated Lumber vs Field-Applied Borates

Some lumber is sold already treated with borates at the mill, often with a blue or green tint and labeled for interior or above-ground use where it stays dry. Mill-treated borate lumber is pressure-impregnated, so the borate reaches deeper into the wood than a spray on site. It is commonly used for sill plates and framing in termite-prone regions such as Hawaii and parts of the Gulf Coast.

Do not confuse it with standard pressure-treated lumber used for decks and fence posts. That lumber uses copper-based preservatives that resist leaching and is rated for outdoor exposure and, in some grades, ground contact. Borate-treated lumber is not, because rain would wash the borate out. Field-applied borates like Bora-Care and Tim-bor are the way to add borate protection to existing framing or to cut ends and drilled holes in new lumber.

DIY or Hire a Pro?

Borate products are sold to homeowners, and spraying accessible bare wood in a crawl space or attic is a manageable DIY job if you can work in a confined space and follow the label carefully. DIY makes most sense for preventive treatment of exposed framing, treating wood during a remodel while walls are open, and treating a small area of powderpost beetle damage.

Hire a licensed pest control company when you have live termites or swarmers, when the problem may be Formosan termites or a widespread drywood infestation, when you need a termite warranty for a home sale, or when treatment requires drilling and injecting walls. Professionals also carry equipment like foam applicators and moisture meters, and they can combine borates with soil treatments that homeowners generally cannot buy or apply.

How Long Does Borate Protection Last?

In interior wood that stays dry, borate protection lasts for many years, because the borate does not break down; it only leaves the wood if water washes it out. Wood that gets repeatedly wet, from plumbing leaks, a flooded crawl space or condensation, can lose protection over time. Keep the structure dry, recheck crawl spaces periodically and retreat any wood that has been wet for long periods or newly exposed during repairs.

Keep a simple record of what you treated, when, and with which product, ideally with a few photos. It helps when you sell the house, when a pest control company inspects later, and when you need to decide what to retreat after a leak or remodel. Mark treated areas on a rough sketch of the crawl space or attic so you do not have to guess years from now.

Borates in a Complete Termite Plan

Termite control works best in layers. Borate-treated wood is one layer; others include a liquid soil termiticide barrier or a monitored bait system around the foundation, moisture control, keeping wood mulch and firewood away from the house, and annual inspections. Our guide on how to get rid of termites compares treatment methods.

If you see live termites, swarmers indoors or fresh damage, call a licensed pest control company for an inspection before deciding on DIY. Many companies use borates as part of their treatment, and a professional can assess whether you are dealing with subterranean, drywood or Formosan termites. Our checklist on choosing a termite company covers what to ask about warranties and retreatments.