A practical, chemistry‑backed DIY wood‑preservation method that protects structural lumber from termites, carpenter ants, rot, and fungus—at a fraction of commercial costs.
🔬 Why Borates Work
Borates are mineral salts that penetrate wood fibers when dissolved in water. As the water evaporates, borate crystals remain embedded inside the wood. These crystals:
- Poison insects like termites and carpenter ants by disrupting their digestive systems
- Prevent rot fungi from colonizing the wood
- Stop mold growth by creating an inhospitable environment
- Remain permanently unless the wood is repeatedly soaked by rain or groundwater
Because borates work internally—not as a surface coating—they don’t flake, peel, or wash off during normal indoor conditions.
🧪 The DIY Recipe
- 1 pound borax
- 1 pound boric acid
- 1 gallon hot water
Stir until fully dissolved. Hot water is essential because it increases solubility and allows the solution to penetrate deeper into the wood.
🛠️ How to Apply It
Use a garden sprayer or paintbrush to saturate exposed wood surfaces such as:
- Joists
- Rafters
- Sill plates
- Subfloor undersides
- Beams in attics, basements, or crawl spaces
The wood should be bare and unpainted so the solution can soak in. One heavy coat is usually enough, though highly absorbent or older wood may benefit from a second application.
🌱 What Happens Inside the Wood
As the solution dries, borates crystallize throughout the wood grain. This internal mineral barrier:
- Blocks termites from tunneling
- Stops carpenter ants from nesting
- Prevents rot fungi from digesting cellulose
- Protects against moisture‑related decay
Because the treatment works from the inside out, it doesn’t require removing drywall or structural components. Any exposed framing can be treated in place.
🏡 Ideal Use Cases
- Older homes with crawl spaces
- Florida homes with high humidity
- Sheds, barns, and workshops
- Renovation projects with exposed framing
- Preventative treatment before installing insulation
This method is especially valuable in regions where subterranean termites are common—like Citrus Springs and Dunnellon—because it adds a layer of protection to structural wood that often goes untreated.
💡 Tips for Best Results
- Apply on dry wood for maximum absorption
- Use warm or hot water to dissolve minerals fully
- Label your sprayer so it’s not reused for gardening
- Store leftover solution in a sealed container
- Reapply only if wood becomes saturated by flooding or leaks


