In order to recognize and combat the wood-destroying fungus, or the so-called dry rot, there are a few important factors to consider. Serpula lacrymans is found in many parts of the world and can attack both forest trees and wooden materials in buildings. Additionally, dry rot is known for its ability to cause major damage to wood in homes or basements. If you are concerned about the possibility of this type of fungal infestation on your property, the following information and tips may help you.
Recognize the difference between wet rot and dry rot
One of the main threats to lumber is wet rot and dry rot. The main difference between the two is the amount of mycelial growth and the ability offungus, on lumberand other building materials. Accordingly, dry rot is characterized by the fact that it spreads through relatively dry wood and other building materials in a property in order to find a food source. Wet rot, on the other hand, cannot spread in this way.
Additionally, the spread of wet rot is limited to its source of moisture. This means it cannot spread everywhere unless there is direct contact with moisture. Dry rot becomes problematic when it spreads into invisible areas of the property such as stairs, attics or floors. Dry rot can occur in any part of the home where there is wood, as long as the environmental conditions for outbreak are present.
Main characteristics of dry rot
The dry rot life cycle consists of four main phases, each with its own telltale signs by which you can identify a dry rot.
- Myzelwachstum:The mycelial growth appears as a white or gray cotton-like substance. Mycelium has the ability to spread extensively across numerous building materials in search of a new food source.
- Fruiting bodies:The fruiting body or sporophore is easily recognizable as it resembles a pizza. These fruiting bodies can appear in a range of shapes and sizes depending on the conditions present. Most of these round house sponges have a rusty deep red color of the spores, with the outer parts of this growth being lighter. The dust from the spores of these fruiting bodies can be the first clue that dry rot is present and a fruiting body is lurking somewhere nearby.
- Affected wood:Since the sole purpose of dry rot is to dry out the wood and remove moisture, the affected wood itself is a good indicator of such a problem. It looks dried out and therefore has shrunk. This wood will most likely be brittle and warped. The grain of the wood can have cuboid cracks.
- Dry rot smell:The most common symptom of dry rot, even without physically seeing the outbreak, is the presence of a damp, musty, and fungal odor. However, this smell does not necessarily mean there is a dry rot problem. But it would certainly indicate a problem with moisture. However, depending on the extent of the problem, moisture can often lead to dry rot.
Recognize the spread of dry rot
Dry rot spores are always present in the atmosphere. However, they are mostly harmless unless the right conditions are present. For it to develop into an infestation, a moisture problem and a lack of ventilation in the property are required. Dry rot begins when these spores land on wood with a moisture content above 20%. Then they begin to germinate and produce hyphae (fine strands of fungus) that are gray in color. This develops into the aforementioned mycelial growth, which varies from gray to pure white under moist conditions.
Although individually these spores are almost invisible to the naked eye, in homes with such problems you will often notice that when grouped together they appear as a tell-tale fine orange or brown dust. Once the hyphal structure is formed, it combines into a mass and these strands grow into and over moist wood and masonry. However, it can also grow over materials such as plaster, mortar, brick, etc. This is because the fungus is looking for more cellulose-containing wood to feed on. It can be difficult to identify dry rot, especially in the early stages. The best evidence of dry rot, such as mycelium and fruiting bodies, occurs later in the life cycle.
Possible damage and effects of dry rot
There are several problems with dry rot, particularly damaging the structural integrity of a building. This can come at a huge financial cost, but can also pose a safety risk for those inside. A house with dry rot is not a pleasant place to be and its evolved forms can permeate the air with a damp, earth-like smell. As the most severe form of fungal infestation, it can also make it difficult to sell a home. In addition, there are possible health risks from dry rot. The dry rot spores described above are not in themselves harmful to health. However, the humid conditions the fungus requires to germinate can pose a health risk to the elderly, infants and people with respiratory illnesses.
Tips for combating dry rot
If you identify dry rot and want to eliminate it, removing the source of moisture should be the core of your control strategy. Wood can become damp for various reasons. The most common causes include leaky washing machines, shower trays, bathtubs, condensation, etc. The moisture can also come from outside the building. These would be, for example, leaky roofs, rising damp or moisture penetrating through walls. Whatever the source of the moisture, you can control the spread only after the wood has dried out properly.
However, it is not always possible or practical to be sure that the wood will remain dry in the long term. It is therefore important that secondary measures are taken to prevent reinfection. You should accordingly remove all affected wood and replace it with pre-treated wood. You should treat leftover wood that could be attacked by dry rot with an effective fungicide. If the dry rot has penetrated the masonry, you should isolate it through physical containment and/or masonry sterilization. Some wood preservatives are particularly suitable for treating dry rot because they penetrate the wood much deeper than conventional preservatives. This gives them a significant performance advantage because no wood preservative can only work once it comes into contact with the fungi it is supposed to protect against.
How to treat dry rot on wood
Once you have identified the infected timbers, it is recommended to cut them on site to at least 500mm beyond the last signs of fungal growth or hyphal structures. You must then remove all fruiting bodies and visible spores. Clean all wall areas to remove surface growth including hyphae, mycelium and fruiting bodies. You can use a stiff brush on the walls if necessary. In addition, you should replace the affected wood with pre-treated wood materials.
Any remaining healthy wood, new and old, should then be treated generously with fungicide of your choice. These specially formulated fungicides kill dry rot and stop reinfestation, preventing further outbreaks of the fungus. You also need to sterilize the masonry. An experienced wood rot expert can determine whether the fungal infection is actually Serpula lacrymans or a type of wet rot. Fungal species such as Coniophora puteana, Poria vaillantii and Phellinus contigus are the most common. For this reason, in such cases it is advisable to commission a specialist to carry out a thorough dry rot examination to be sure.
