Can I Use Antifreeze to Fix Wood Dry Rot?

About Dry Rot

• "Dry rot" describes damage caused to wood by any one of several species of wood-eating fungus. Serpula lacrymans, which causes "brown rot," is one of these. As the fungus grows, it breaks down the cellulose of the wood, leaving behind only the weaker lignin. The resulting damage leaves the wood dry, brittle and blocky in appearance. Over time, dry rot damage can accumulate to cause dangerous structural instability.

Protection From Moisture

• Treating dry rot fungus and preventing future infections is a two-step process. The first step is to locate any areas where moisture is coming into contact with the wood. Excessive and consistent moisture is what allows dry rot fungus to get a foothold in the first place, so it's critical to stop water from getting in.

Antifreeze Antifungal Treatment

• The next step is to soak the affected wood in an antifungal agent, both to kill existing fungus and discourage future infection. You can use ethylene glycol or propylene glycol antifreeze for this just as you would a glycol-based borate solution. Oregon State University entomologist Jack DeAngelis writes that glycol may actually improve absorption of the solution by the wood fibers, such that both antifreeze and glycol borate solution will penetrate the wood more thoroughly than will a solution of borate powder in water.

Epoxy Sealant

• The next step in dry rot restoration is to brush solvent-thinned epoxy onto the wood. This seals the wood against future moisture incursions and fungal invasions. It also reinforces the stability of the wood to some extent, though you shouldn't rely on this to renew the structural integrity of load-bearing pieces. If there are large holes, Paul Oman of Progressive Epoxy Polymers, Inc. suggests filling them in with wooden plugs to save on epoxy and incorporate more actual wood into the repair.

Epoxy-only Process

• Oman says that the antifreeze treatment is optional because the epoxy seal will kill the fungus on its own. However, he notes that epoxy will not penetrate as thoroughly as glycol solutions will.

Structural Triage

• Do not attempt to repair by this method any wood that has sustained enough damage as to be structurally unsound. Epoxy will not restore the wood's ability to provide safe stability and support. Instead, replace these sections of wood with new timber. This may require the services of a professional carpenter.

Toxicity

• Ethylene glycol antifreeze can be lethal if ingested, even in small amounts. According to the Michigan Department of Environmental Quality, it takes as little as two tablespoons to cause serious damage to children, and even less than to be fatal to dogs and cats. Propylene glycol has a lower toxicity rating than ethylene glycol, but can still cause serious health effects. Keep all antifreeze in tightly sealed, clearly labeled containers out of reach of children.

Environmental Concerns

• Because antifreeze poses risks of environmental contamination, special consideration must be taken in disposing of it. This is true even if the antifreeze is labeled "environmentally friendly." Never pour antifreeze down drains or out on the ground where it can seep into waterways or wind up in septic systems. Never simply discard antifreeze in your trash. Instead, contact your local recycling coordinator or household hazardous waste collection departments for help to properly disposing of used or unused antifreeze.