Serpula lacrymans
Description
Serpula lacrymans is perhaps the most serious form of fungal decay. It attacks timber, generating moisture from digesting the surface it grows on. Unlike the less dangerous wet rot, dry rot can spread through damp brickwork and plaster, allowing it to spread throughout a building with ease.
This fungus normally feeds off of woodland timber but is known to also affect the wood in both ships and buildings. Its common name comes from how it consumes the cell walls which give timber its strength, leaving it dry and brittle.
The dry rot fungus uses non-enzymatic mechanisms to modify lignin and initiate the breakdown of cellulose. Hydrolytic cellulases and oxidative enzymes are then used to fully degrade and metabolize the cellulose. Various myths associated with the destructive nature of the dry rot fungus often lead to the use of harsh and destructive treatment that cause more damage to the building than the fungus itself.
It’s one of the most difficult types of rot to treat and can even lead to timber and brickwork collapsing in extreme cases.
Common names: Dry Rot.
Serpula lacrymans Health Risk
Of all the timber fungi, dry rot is one of the most dangerous, not just to the integrity of your building, but because of the underlying damp problem it represents. Whilst dry rot on its own won’t cause too many health problems, it can cause costly structural damage that will eventually become a health hazard.
Dry rot is not believed to produce any toxic chemicals or compounds and is therefore not too much of a threat to your health directly, however, a small number of hyper sensitivity cases to the fungus have been reported.
More pressingly, the presence of dry rot in your home indicates high levels of dampness and condensation, which can cause respiratory problems and make underlying conditions, such as asthma, worse. Furthermore, dry rot eats through your timbers, causing them to weaken and eventually collapse - this can cause serious health and safety concerns.
Serpula lacrymans Growth Cycle
When spores take root on a piece of hospitable wood, they begin to take root. These roots, or hyphae, grow and merge to create a white, fluffy-looking growth known as mycelium.
Mycelium growth eventually becomes weakened by exposure to sunlight or the absence of moisture, air, or consumable wood. At this stage, the fungus begins to produce spore caps known as sporophores, which release more spores into the air. The new spores then spread and land on surfaces, causing more dry rot when the conditions are right.
Serpula lacrymans Treatment
Dry Rot removal is complex and should only be carried out by professionals.
The single most important step in treating a dry rot problem is to get rid of the source of moisture. This may involve repairing a damaged roof or wall, replacing leaky pipes, or other measures. Afterward, the wood itself must be dried, and you may wish to add additional ventilation to help reduce humidity. After these basic steps have been taken, there are several treatment options available.
Borates
Borate-based preservatives are often used to treat new wood, and may also be used as a means to destroy dry rot in existing wood. This method involves either drilling holes in the affected wood and injecting a borate solution or spraying the solution over the infected wood. The most common borate solution used for treating an existing problem is Bora-Care.
Tim-Bor is another popular borate solution that comes as a water-soluble powder that is sprayed onto all wood surfaces. The coating may protect your timber for up to 30 years and is also commonly used as a termite barrier.
A major downside to using borates is the fact that they’re water-soluble. While this helps them penetrate the wood more deeply, it also means the protective coating will wash away over time if there is an ongoing moisture problem. Any white coating which appears on the wood’s surface after treating must be washed off and that are allowed to dry.
Glycol
Another popular chemical treatment method, glycol is a chemical component in antifreeze and other de-icing solutions. Ethylene glycol may cause serious health problems with too much exposure. Propylene glycol, alternatively, is made using less toxic chemicals.
While glycol treatments may become diluted or wash away in a high-moisture environment, it can be sprayed on painted or coated wood surfaces, absorbing into the wood quickly without damaging the surface. The exceptions to this are epoxy and polyurethane, which are more resistant.
Heat
Dry rot is susceptible to high temperatures. Thus, some heat-treated methods used in pest control may also be used to treat dry rot. Two of these methods are heat fumigation and microwave treatment.
For heat fumigation techniques, specific rooms or even your entire home is covered in tarpaulin. All heat-sensitive objects are removed from the treatment area, which is then heated to dry out and kill the fungus. This method can be very expensive and is not widely available.
Alternatively, microwave treatment is a newer method that requires special equipment. The use of microwaves can be effective, but it’s also costly and can only target small areas. Microwave treatment can also cause heat damage, making its use far less favorable than other, more proven methods.
Home Remedies
While not as effective, it is possible to make rudimentary fungicides out of common household ingredients. Many of these products alter the pH balance of the wood, making it less hospitable to the dry rot.
Examples of common household products used include hydrogen peroxide, baking soda, and vinegar. There are some commercial fungicides made from similar ingredients, although chemical fungicides have more field testing.
Replacement
An expensive but highly effective method is to remove all wood that has been affected by dry rot. The surrounding areas should be treated with fungicides to kill any additional traces of the fungus. This method has been traditionally used to combat dry rot, which was considered very difficult to eliminate.
As more methods arise to get rid of dry rot for less cost and effort, it is becoming less common to replace wood which has not been seriously compromised.
Photo sources:
Photo 1 - Author: Majavamm.jpg: Eppderivative work: Ak ccm (talk) (CC BY-SA 3.0)
Photo 2 - Author: Energiesorgenfrei (Diskussion) (CC BY-SA 3.0)
Photo 3 - Author: Boatbuilder (CC BY-SA 3.0)
