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What Is Dry Rot?

Dry rot is arguably the worst type of problem which can be faced by property owners. If you have concerns that your property is suffering from timber decay then you are on the right page. This page will help you to gain a better understanding of what dry rot is. Continue reading to learn more about the causes dry rot, its differences with wet rot and the key signs which you need to know in order to identify rot problem as soon as possible.

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Dry Rot

Dry Rot is a wood destroying fungi which cause timber decay by feeding of the cells of the wood and reducing its strength. It used to be a term used to describe any type of decay affecting wood in buildings and ships caused by a fungus which resulted in deterioration in the form of darkened, weakened and cracked wood. Timber rot attack within a property is regarded as a serious infestation which can prove to be very difficult and costly for property owners to remove. Occasionally, substantial remedies are required in order to repair the damage which dry rot causes.

Dry rot’s life cycle can be split up into four specific sections. The rot starts out as a microscopic spore which when gathered in high enough numbers, may appear like a slight orange/red dusting. If spores are subjected to high enough levels of moisture they will germinate and then they will start to grow slight white strands. These strands are called hyphae. As the hyphae develop, they will then form a considerably sized mass which is called mycelium, which looks like cotton wool when fresh. The last stage is a fruiting body which pumps new spores into the surrounding air.

Dry rot can begin when excessive dampness affects the timber, in conjunction with decreased ventilation, allows the spores to germinate. It can affect any unprotected or untreated timber which becomes damp and can occur in any type of property, modern or historic. It likes the dark and can develop in roof voids under floors or behind wall fabric when the conditions are right.

Dry Rot happens to be a slightly ironic name for the infection. For dry rot to occur it needs timber to be slightly more wet than what it would normally be. Timber will need to have a moisture level of between 28% and 30% for the fungal spores to develop and begin producing hyphae. Once the fungus has developed a moisture content of just 20% is required for the fungus to survive.

How To Identify Dry Rot Signs?

Untreated dry rot can cause serious structural damage to the timbers and fabric of your property which may prove to be very costly to rectify. Therefore, it is critical to identify the rot attack as early as possible to minimise the property damage. It is also important to identify if the fungal outbreak affecting the timber is dry rot or wet rot. This is because unlike wet rot, dry rot is capable of travel through building materials, meaning that the problem can rapidly spread throughout an entire building. In order to ensure that you have the best chance of identifying a rot problem as quickly as possible, it’s important to familiarise yourself with the clearest signs of a dry rot attack.

Typical signs of dry rot include:

  • Fluffy, white mycelium develops under humid conditions, this has a ‘cotton wool’ like appearance.
  • Darkened, cracking or shrinking wood.
  • Visible strands developing, these tend to be brittle.
  • The decay will result in a damp, musty odour.
  • Around the infection, it is likely to identify red coloured spore dust coming from a fruiting body.

The most problematic rot infestations tend to be those which occur in non-visible sections of your property such as in attics, under flooring or behind wall fabric. This is because the dry rot infestation is likely to have grown for a considerable amount of time before it is identified as a problem which needs resolved and the problem may have spread considerably by that point. Timber decay can occur in any part of your property where there is unprotected timber so long as the necessary environmental conditions exist for the outbreak to occur.

As previously mentioned, there is four key stages to a rot outbreak. Within those stages there are numerous signs which will occur which can help people to identify the problem they are suffering from.

Growing Mycelium
Mycelium will normally grow as a white or grey substance which has a cotton wool appearance. Mycelium is capable of spreading considerably over and through various building materials in the search for new sources of food.

Sporophore
It is very easy to identify the sporophore or fruiting body due to the way that it slightly resembles a pizza. Most of these bodies appear with a rusty red colour with the external parts of this growth development exhibiting a lighter white like colour. This dusting from the spore could be the first possible indication to a property owner that dry rot may be present in their property.

Timber Being Affected
Dry rot removes moisture from timber effectively drying it and takes the moisture to dampen down new timber to feed off. A clear indication of a rot issue is an examination of the timber itself. The wood will have a dried-out appearance and will also have shrunk and caused cuboidal cracking to the timber.

Distinct Smell
Dry rot tends to have an obvious mushroom, musty and damp smell. Although this smell doesn’t necessarily indicate a dry rot problem specifically, it does highlight that the property is suffering from dampness. Ultimately, dampness can lead to a rot problem affecting your property, so it is crucial that the damp issue is fixed and eliminated from your property as soon as possible. Rot can become a very serious issue which can prove extremely problematic for property owners.

What Causes Dry Rot?

Timber can become damp for two specific reasons, which can then result in dry rot developing.

1. Moisture has affected timber due to a property damp issue which has not been rectified.
Upon resolving any damp problem which you have identified, you may believe that you have sorted any issues. Unfortunately, any dry rot which started while the timber was damp may still be present and developing. All types of damp issues, such as penetrating damp and rising damp can dampen the timber in your property. If you have identified a rot problem in your property, it is likely that the attack has started as a result of a damp issue. It is important that you resolve the damp issue which was the source of the dry rot problem.

2. Untreated Timber Was Used When Your Property Was Built.
If your house was built a long time ago, there is a good chance that it was built without the timber being pre-treated with a fungicidal to protect it against a wood destroying fungal attack such as dry rot. Pre-treated timber is now generally used by builders for any internal building work.

Dry rot happens when spores which are airborne come into contact with dampened timber which is unprotected by a fungicide and has a moisture content of more than 20%. These spores can then germinate and cause white rooted strands. The fungus will consume the wood, which in turn sucks the moisture from it which makes the wood considerably weaker. When there is a well-established dry rot attack the fungus then creates a sporophore (fruiting body) as previously mentioned, which continuously produced spores in order to keep progressing the life cycle of the dry rot.

What are the Differences between Wet Rot and Dry Rot?

Our property surveyors are commonly asked what the differences are between dry and wet rot. There are some very stark differences between the different types of wood destroying fungi.

Wet Rot Symptoms

    1. Wet rot fungi affect the timber where the damp has caused the outbreak and does not spread far away from the source of moisture.
    2. Where surface cracking is evident the cracking is generally less severe than dry rot affected timber.
    3. The mycelium is a dark brown growth which is rarely seen.
    4. The wood can feel spongy and soft which is an obvious sign that the wood is structurally damaged.
    5. The timber can keep a surface veneer even although the timber is rotten under the surface. In some cases, paintwork may look externally perfect but the timber could be rotting underneath.

Our wet rot page provides a lot more information and visual aids for you to get a better understanding of what wet rot is.

Dry Rot Symptoms

      1. Dry rot mycelium will spread away from the source of dampness and go through cracks in walls to reach other timber to attack.
      2. Dry rot will leave visible deep cracks across and along the wood’s grain which is caused by shrinkage of the rotten timber.
      3. The mycelium is white like cotton wool when fresh.
      4. When the dry rot attack is well established it creates a fruiting body which then spreads new spores.

Our dry rot page provides a lot more information and visual aids for you to get a better understanding of what dry rot is.

Dry rot is much more serious than wet rot as it can spread and attack adjacent dry timbers and affect a property from the roof to the ground floor.

The most notable difference between both types of rot is that wet rot fungus usually germinates on timbers which have a higher moisture content than what is required for dry rot germination. Wet rot tends to develop on timber which has a moisture content of approximately 40%. Whereas dry rot can grow on timber which have moisture content of 20%.

Without the appropriate treatment, rot can cause serious structural issues to properties due to the timber losing its normal strength.

What To Do Next?

As soon as you suspect a timber decay issue in your property it is imperative that you take action to resolve it as soon as possible because of the way that it can spread rapidly in your property. Treating timber issues is a specialist job, which not only involves repairing the fabric of your property affected by the rot attack but also replacing or repairing all affected structural floor, roof and wall timbers. A very important aspect of the repair process is to identify and stop the source of damp or water which caused the rot attack in the first instance.

For over 85 years Richardson & Starling have successfully eradicated thousands of rot attacks. Contact your local branch for advice or to arrange a free property survey  if your property is within 25 miles of our nearest branch (terms apply). Our specialists have the necessary experience and resources in order to investigate and deal with your timber decay problem efficiently to get your property back to normal as quickly as possible. After utilising our specialists, you can be safe in the knowledge that the work to eradicate your dry rot attack is covered by a 30 year guarantee you can trust. It is critical that property owners utilise professional and accredited (PCA) damp specialists. Misdiagnosis of your damp or rot problem can prove very damaging to properties as the problem may become more widespread and become considerably more costly to resolve than if it had been sorted effectively at the beginning.

Free Timber Decay Advice

Have you noticed any timber decay signs in your property? Contact your local branch for advice or a property survey today!

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