Dry rot destroys wood by attacking it with fungal spores known as Serpula lacrynens. Antifreeze is an effective treatment. It saturates the dry rot and kills the fungal spores. It also blends with any moisture below the surface of the wood and destroys wet rot spores. Antifreeze is a water-based solution available at shops that stock motoring products. It contains either ethylene glycol or propylene glycol. To increase the effectiveness of antifreeze when applying it to dry rot, you should mix it with borax powder and boric acid.
Create a mix of antifreeze, borax powder and boric acid. The proportions should be 50 per cent antifreeze, 28 per cent borax powder and 22 per cent boric acid. You should determine these percentages by weight. If you wish to have 50 g of dry rot solution, use 25 g of antifreeze, 14 g of borax powder and 11 g of boric acid. You can buy borax powder at shops that sell laundry items. Boric acid comes in powder or crystal form. Supermarkets often sell it alongside cleaning products.
Pour your solution of antifreeze, borax powder and boric acid into a saucepan and heat gently. Regularly check the solution with a thermometer. Remove the saucepan from the heat when the temperature has reached 126 degrees. At this temperature, much of the water in the solution will have boiled away. When the solution has cooled, add further antifreeze equivalent to the amount you originally used. For example, if you used the amount given in Step 1 above, you should add 25 g. This extra antifreeze helps to make the solution easier to apply to dry rot. Stir the solution and pour into a plastic or tin container.
Drill holes at regular intervals in the wood affected by dry rot. Carefully pour the solution into the holes. Also apply the solution onto the dry rot with a standard paint brush. After the antifreeze has dried, you may wish to improve the condition of the damaged wood. Proprietary treatments can bond the wood fibres that dry rot has spoiled.
Antifreeze based on ethylene glycol is toxic for humans and pets. If possible, use a less harmful antifreeze based on propylene glycol.
Boric acid also has toxic properties. Wear a mask and gloves when using it.