How To Identify Dry Rot

What does dry rot look like and what can you do as a homeowner to identify the problem? Dry rot becomes problematic and difficult for property owners when a dry rot outbreak progresses in non-visible areas of your property such as your stairs, loft, attic or flooring.

Dry rot can be found in any part of your home where there is timber so long as the environmental conditions exist for the outbreak.

Graham Malpass

Accredited to

Graham Malpass

Senior Remedial Surveyor and Waterproofing Design Specialist CSRT CSSW
North West

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The Dry Rot Life Cycle consists of four main stages, each with their own tell­tale signs that can help you identify a dry rot outbreak.

Mycelium Growth

Mycelium Growth

Mycelium growth will appear as a white or grey cotton wool like substance. Mycelium has the ability to spread extensively across numerous building materials in search for a new source of food - in this case, wood.

Fruiting Body

Fruiting body (Sporophore)

The fruiting body or sporophore is easily identifiable with its ‘pizza-like’ appearance. These fruiting bodies can appear in an array of shapes and sizes dependant on the conditions present. Most of these round-shaped fruiting bodies are a rusty deep red colour (the spores) with the outer parts of this growth being a much lighter white colour. The spore dust from these fruiting bodies can be the first indication to a property owner that dry rot is present and a fruiting body is lurking somewhere nearby.

Affected Timber

Affected Wood

As dry rot’s sole purpose is to dry out and remove moisture from the ood, a good indicator of a dry rot issue is the affected wood itself. This will look dried out and will have therefore shrunk as a result. This wood will most likely be brittle and warped and the grain of the wood will have cuboidal shaped cracking features.

How To Identify Dry Rot

Dry Rot Smell

The most common symptom of dry rot, even without physically seeing the outbreak, are the presence of a damp, musty and fungal smell. The smell may not necessarily mean there is a dry rot issue, but would certainly indicate an issue with dampness; however dampness can often lead to dry rot depending on the extent of the issue.

What are the Differences between Wet Rot and Dry Rot?

We are often asked by customers: “What is the difference between wet rot and dry rot?” We can tell you that there are major differences between these two very different types of wood rot.

Identifying Wet Rot

  1. The wood is more often than not going to feel soft and spongy – a clear indication of structural damage to the wood.
  2. Typically a black fungus appears on the infected wood.
  3. Any paint finish on the timber will become damaged. However, in some instances, the paintwork can look perfect on the exterior but may well be rotting underneath the paint.
  4. If the decay is in an advanced state it will have dried out the wood. This ten means that the wood will crack and crumble easily.

You can find more information and pictures on our identifying wet rot page.

Identifying Dry Rot

  • When exposed to light the fungus appears to have a lemon almost yellowish tinge look to it.
  • Dry rot leaves deep cracks running across the grain of the wood along with evidence of mycelium growth on the wood.
  • The affected wood will be brown in colour and will crumble due to a lack of structural integrity as a result of dry rot using the wood as a food source.
  • Ordinarily damage is restricted to the wood, however, in some instances a large flat mushroom-like fruiting bodies may also be visible. These can easily grow through decorative finishes such as plaster or paintwork.
  • Dry rot is the much more serious form of rot out of the two as it can spread over a larger area compared to wet rot.
  • Wet rot fungus tends to grow on more porous surfaces, for example, wood with a high moisture content of around 50%. Dry rot, however, tends to grow on surfaces where there is a moisture of around 20%. If left untreated wet rot will almost certainly cause major structural issues as a result of structurally weakened timbers.

Does Dry Rot spread?

Dry rot is a living growing fungus. As such it feeds on timbers and will actively seek out new food sources when it has to. New sources of food been fresh timbers. If the humidity conditions are right dry rot can spread rapidly through a property on the hunt for food.

How to Deal With Dry Rot

Dry rot should be treated as soon as possible to avoid severe damage occurring. If you do suspect dry rot might be causing damage to timbers in your property then the best option is to request a dry rot survey as soon as possible.
If you want to understand more about treating dry rot then click the following link.

Concerns with Dry Rot and Wet Rot

Firstly, there is only one true type of dry rot, in contrast to wet rot where there are many variants! The main difference between dry rot and wet rot, however, is the amount of growth of mycelium and the ability of the fungus to spread onto building materials. Dry rot has the ability to spread over relatively dry timber and other building materials in a property to find a source of food (in this case damp wood), Wet rot, on the other hand, cannot spread in this manner. The spread of a wet rot outbreak is confined to its moisture source, meaning it cannot progress throughout a property unless it has direct contact with moisture.

If you are concerned about the possibility of a dry rot outbreak in your property, or to request a dry rot survey, do not hesitate to get in touch with Timberwise.