Wood rot isn’t just an eyesore; it’s also a clear indicator of multiple health and safety risks. If your wooden fixtures are beginning to rot inside or outside your home or commercial space, you must take action to repair and replace the affected areas. Otherwise, you’re putting yourself and others in harm’s way. Let’s go over four of the major health and safety risks caused by or associated with rotting wood.
The dry rot fungus, Serpula lacrymans, is one of the most destructive wood decay fungi in buildings in many countries around the world. Due to its destructive nature, Serpula lacrymans is often referred to as a “building cancer”.
It can also cause structural damage to masonry. The fungus thrives in poorly ventilated, dark places with elevated moisture levels. As such, it is frequently able to spread extensively before the damage is noticed. Dry rot fungus is almost completely restricted to the built environment.
It is a good coloniser of wood within the built environment because it has a highly efficient transport system which allows movement of water, nitrogen, iron, etc. via specialised root-like structures (rhizomorphs) and effective solubilisation system which allows extraction of metal ions from stone and plasterwork.
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 metabolise 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.
For example, it is erroneously believed that the fungus is indestructible and that the whole building would have to be pulled down once infested. The dry rot fungus, however, is vulnerable to dry conditions and hence would not survive for long in the absence of moisture.
At Hitch Property Constructions, we offer timber repairs work from simple timber repair to almost new structures, renovations, and extensions.
What Are the Types of Wood Rot?
Wood rot includes dry rot and wet rot, and fungi cause both. Many types of fungi may cause wet rot, and it is more common if a lot of moisture is present. This fungus prefers wood with a moisture content of at least 50 per cent. Dry rot, on the other hand, only needs about 20 to 30 per cent of moisture to begin to germinate.
Unlike wet rot, the Serpula Lacrymans fungi only cause dry rot, and it doesn’t just stop with timber. This type of fungus is extremely aggressive and can spread across your fence. If spores make it inside your home or to other materials, they can spread the rot.
What Are the Signs of Dry Rot vs. Wet Rot?
Dry rot often comes with cracking timber. Your fence boards may start to split, crack, or even shrink after exposure. In some cases, however, the damage is below the surface of the fence, so you can’t even see it. As the fungi spread, it may promote yellow or grey mycelium. Eventually, you may even see fruiting bodies that can expel even more spores.
Wet rot may also cause shrinking and cracks, but the wood is usually soft and damp. You also might notice a musty odour. Mycelium strands aren’t as common as with dry rot, but they may begin to sprout if left untreated.
Which Type of Wood Rot Is Worse?
Without a doubt, dry rot is almost always worse than wet rot and needs treatment as soon as possible. Luckily, the reason dry rot is so bad isn’t that it can make you sick. Dry rot is terrible because it can drastically impact your wallet.
The fungal infection can spread to just about any material, so it may not stay on your fence. It can attack your deck, patio, and if it gets inside your home, carpets or drywall. This leads to expensive replacement and repairs throughout your entire home.
How Can You Prevent and Treat Wood Rot?
One way to prevent wood rot is by making sure you have minimal moisture, which starts with finding the cause of the excess moisture. For example, your fence may have exposure to lots of standing water if your yard can’t drain properly.
By fixing this, you may prevent wood rot before it even starts. You can also better protect the wood from rot by ensuring it has proper paint or stain to create a moisture barrier.
If you have wet rot, once you find the source of the moisture, fixing the problem mostly involves using a fungicide to kill the fungus, causing the rot. Dry rot, on the other hand, may require a lot more attention. You may need to remove any affected wood, which can become expensive fully. You may also need to use a fungicide to kill any remaining spores.
Wood rot can affect any piece of wood, as long as moisture is around. While both are frustrating and require immediate attention, dry rot can be more aggressive and may spread to other parts of your yard or home. If you would like to know more about root rot and other risks for your wooden fence
Wood Rot Fungi
What are wood rot fungi? Wood is one of the major components of building materials in residential and office buildings. It’s almost impossible to miss a wooden item in a building. It is subject to attack by wood rot fungi and other organisms if it’s not well preserved.
Growth Requirements for wood rot fungi
For fungi to colonise wood, the following conditions are required:
- Favourable temperatures. Generally, wood colonising fungi have an optimal growth temperature at around 25 degrees Celsius.
- Adequate moisture. Moisture is the most critical requirement for fungi to colonise wood. Fungi will not attack dry wood (i.e., with a moisture content of 19 per cent or less). Decay fungi require a wood moisture content of about 30%.
- Adequate oxygen. Most fungi require (oxygen) for growth.
- Food source. Like every other living organism, fungi require nutrients for growth. These are readily available on wood surfaces in the form of dust. The wood itself is made of biodegradable compounds (cellulose, hemicellulose, lignin).
The wood-decaying fungi are the most damaging of all the wood-destroying fungi. These fungi are prolific producers of strong enzymes that they use to breakdown complex wood components (cellulose, hemicellulose, lignin) to simple sugars that they can utilise as food.
Wood-decay fungi colonise the sapwood and heartwood of most tree species. These fungi grow inside the wood or on wood surfaces. On the wood surface, they appear as fan-shaped patches of fine, threadlike, cottony growths or as rootlike shapes. The colour of these growths may range from white through light brown, bright yellow, and dark brown. The spore-producing structures (fruiting bodies) of the fungus may take the form of mushrooms, shelflike brackets, or flattened, crustlike structures. Fine, threadlike fungal strands called mycelia grow throughout the wood and excrete enzymes that digest parts of the wood as food. By breaking down the cellulose, hemicellulose, and lignin wood, the strength and other properties of the wood are destroyed.
The rate of decay and the extent of deterioration depends on the duration of favourable conditions for fungal growth. Decay will stop when the moisture content is lower than the fungus requirements. Decay slows down significantly if the temperature of the wood is either too low or too high. Early decay is more easily noted on freshly exposed surfaces of unseasoned wood than on wood that has been exposed and discoloured by the weather. Wood decay fungi are generally grouped into three major categories: brown rot, white rot, and soft rot.
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Brown rot fungi such as Poria monticola and Serpula lacrymans break down primarily the cellulose component of wood for food, leaving a brown residue of lignin. Wood severely infested with brown rot fungi is greatly weakened even before the decay is visible. Advanced stages of brown rot infestation are characterised by:
- The dark brown colour of the wood
- Excessive shrinkage
- Cross-grain cracking
- The ease with which the dry wood substance can be crushed to a brown powder.
Brown rot fungi are probably the most important cause of the decay of softwoods used in aboveground construction in North America. Brown rot-decayed wood, when dry, is sometimes called “dry rot.”
A few fungi such as Serpula layman can decay relatively dry wood by using water-conducting strands (rootlike structures called rhizomorphs) that can carry water from damp soil to wood in lumber piles or buildings. These fungi can decay wood that otherwise would be too dry for decay to occur. They are sometimes called the “dry rot fungi” or “water-conducting fungi.”
The white-rot fungi, Phellinus megalopolis and Poria contigua break down both lignin and cellulose in wood. They have a bleaching effect that may make the damaged wood appear whiter than normal. Affected wood shows normal shrinkage and usually does not collapse or crack across the grain as with brown rot damage. However, the infested wood loses its strength gradually until it becomes spongy to the touch. White rot fungi usually attack hardwoods, but several species can also cause softwood decay.
Penicillium on woodSoft rot fungi such as Chaetomium globosum usually attacks very wet wood, causing a gradual and shallow (3-4 mm) softening from the surface inward that resembles brown rot. The infested wood surface darkens and becomes very soft, hence the name soft rot.
Unlike the wood-decay fungi, wood-staining fungi are only a cosmetic problem. They tend to grow on the surface of the wood. Examples of wood staining fungi include Ceratostomella spp. and Diplodia spp. These fungi penetrate and discolour sapwood, particularly of softwood species. Typical sap stain, unlike staining by mould fungi, cannot be removed by brushing or planing. Sapstain fungi may become established in the sapwood of standing trees, sawlogs, lumber, and timbers soon after they are cut and before they can be adequately dried. The strength of the wood is not greatly affected, but the wood may not be fit for use where appearance is important (such as siding, trim, furniture, and exterior millwork that is to be clear-finished).
Superficial Wood Colonizing Fungi
Superficial wood colonising fungi such as Fusarium spp and Penicillium spp., first become noticeable as green, yellow, brown, or black, fuzzy or powdery surface growths on the wood surface. The coloured spores they produce can usually be brushed, washed, or surfaced off. On open-pored hardwoods, however, the surface moulds may cause stains too deep to be easily removed. Freshly cut or seasoned wood stockpiled during warm, humid weather may be noticeably discoloured with mould in less than a week. Moulds do not reduce wood strength, but they can increase the capacity of wood to absorb moisture, thus increasing the potential of attack by decay fungi.
Is dry rot fungus dangerous to your health?
There are no known toxic chemical compounds produced by the dry rot fungus. However, the existence of asthma associated with this fungus has been documented. The sensitising role of this fungus was confirmed in atopic and asthmatic individuals by both skin tests and by bronchial provocation tests. A small number of confirmed cases of hypersensitivity pneumonitis (allergic alveolitis) caused by the dry rot fungus have been reported.
How to detect dry rot fungus
Dry rot fungus is likely to be found in buildings where bad maintenance, particularly of old properties, and inappropriate design or alteration may result in water intrusion. In the early stages of infestation, the dry rot fungus is difficult to distinguish from other wood-rotting fungi without proper laboratory testing visually.
However, at an advanced stage of infestation when the fruiting bodies have developed brown spore dust, the fungus is relatively easy to distinguish from other wood rot fungi. Unlike other wood rot fungi, the dry rot fungus is able to spread to other wood, even through masonry materials. This ability to spread is one of the distinguishing and threatening characteristics of the dry rot fungus.
How to control dry rot fungus
The dry rot fungus can be readily controlled with the proper combination of environmental manipulations and building considerations coupled with the proper use of wood and masonry preservatives.
Other wood-rotting fungi in houses
Another type of rot caused by fungi on wood in houses is the wet rot. Unlike the dry rot fungus, wet rot fungi destroy both cellulose and lignin, leaving the colour of the wood largely unaltered but producing a soft felty or spongy texture without cross cracks. Wet rot could either be brown or white rot.
Common white rots are caused by fungi Donkiporia expanse, Asterostroma spp, Pleurotus ostreatus and Phellinus contiguus. Brown rots cause the wood to become darker in colour and to crack along and across the grain; when dry, very decayed wood will crumble to dust. Many common wet rots are brown rots caused by fungi such as Coniophora puteana, C. marmorata, Paxillus panuoides and Dacrymyces stillatus.
Health and Safety Risks by Rotting Wood
While rotted wood is not the cause of respiratory problems, it indicates an excessive amount of moisture in the air, as well as the growth of potentially harmful fungi such as black mould. In these damp conditions, mould can spread rapidly, releasing spores in the air that, when inhaled, can lead to coughing, sneezing, lung inflammation, and other breathing difficulties.
Irritation and Rashes
If mould is indeed the culprit behind your wood rot, it can also lead to other health issues, such as skin rashes, eye irritation, headaches, and exhaustion. Once again, the rotting wood does not directly cause these issues. The fungi that cause the rot is a result of warm, damp conditions which are the true menace. Still, when you locate wood rot, there is a good chance that your health will be negatively affected by these areas.
Gaps, Cracks, and Open Spaces
Wood rot can also leave your home’s or building’s interior exposed to external factors such as insects, mice and other pests, bacteria, and more. Some of these unwanted visitors can carry various diseases. It’s crucial that your interior is well sealed from these forces, especially around windows, doors, seams, and other potential entry points.
By and large, the most dangerous safety risk posed by rotting wood is structural degradation. When maintained properly, wood is durable, flexible, and strong, making it a common and viable construction material. Many homes and buildings use wooden building materials as supporting features. Additionally, many decks, patios, and balconies are constructed from various types of wood.
If these wooden features begin to rot, however, they become softer and weaker, making them less able to remain stable against weight and pressure. Eventually, the wood foundation might break down completely, taking the whole structure down with it. This can severely harm anyone on top of or underneath the structure at the time of the collapse.
How Can You Prevent Rotting Wood?
By preventing wood rot from taking hold, you can greatly reduce the health and safety risks listed above. There are a number of measures you can take to prevent moisture from entering your building, such as keeping gutters clear and clean, placing dehumidifiers in basements and attics, investing in better insulation, and improving overall ventilation.
You should also protect your wooden features from rot directly. Make sure you clean your wooden surfaces on a regular basis. Paint, stain, and/or seal your wooden features to prevent moisture from getting into the wood’s pores. If you’re not sure what type of paint or stain to use, hire a residential painting or commercial painting service to help.
Pay special attention to your exterior wooden features, as these are more exposed to moisture from rain, snow, and vapour. And before you begin exterior painting, make sure to pressure wash all wooden surfaces.
Can dry rot make you sick?
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, and it can cause costly structural damage that will eventually become a health hazard.
Thereof, can dry rot affect your health?
Dry rot spores on their own are not a health risk. However, it does indicate an underlying damp problem of excessive moisture within the property which can potentially be bad for your health.
Also, Know, can rotten wood make you sick? You can get blastomycosis by contact with moist soil, most commonly where there are rotting wood and leaves. The fungus enters the body through the lungs, where the infection starts. The fungus can then spread to other parts of the body. The disease may affect the skin, bones and joints, and other areas.
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Thereof, what are the first signs of dry rot?
Typical indications of dry rot include:
- Wood shrinks darken and crack in a ‘cuboidal’ manner (see picture)
- A silky grey to mushroom coloured skin frequently tinged with patches of lilac and yellow often develops under less humid conditions.
- White, fluffy ‘cotton wool’ mycelium develops under humid conditions.
Dry rot is one of the most serious forms of damp that can manifest itself in property and, if left untreated, it can cause potentially irreversible damage to the building. Often, the presence of dry rot does not come to light until the damage has already been done due to the areas in which the issue is likely to be.