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What are the Stages of Dry Rot?

Dry Rot in Wooden Frame

If you have noticed a brown type of mould on wood in your property, or if it appears to be cracked and crumbly, it’s likely you’ve got a case of dry rot. In this blog, we’ll explore the stages of dry rot and how it can be treated and prevented.

What is Dry Rot?

Dry rot is a form of wood decay. It is caused by a type of fungus that grows in wood with moisture levels exceeding 28%, but once the fungus is established in the wood, it can lay dormant in environments with as low as 22% moisture. Dry rot can affect masonry, too.

How to Spot Dry Rot

Dry rot is often referred to as ‘brown rot’ because of its characteristically red-brown appearance and tendency to darken the colour of the timber. This is its defining feature, but there are other ways to diagnose dry rot:

  • Decaying wood with deep cuboidal cracks or a crumbly consistency
  • Brown, orange or red spore dust patches
  • Mushroom-like growths on timber
  • Sap in crevices between skirting boards and the floor, or between architraves (moulding around doors/windows) and walls
  • Grey strands or a silver-grey skin on wood
  • A damp smell in the room

The Difference Between Dry Rot and Wet Rot

Wet rot and dry rot often get confused, and whilst they’re both destructive, they are very different problems. It’s essential the right treatment is applied to avoid further damage and expense, so knowing the difference is key. Here are some of the key differences you should be aware of:

  • Wet rot requires a very high moisture content, sometimes upwards of 50%, whereas dry rot can exist in areas with as little as 22% moisture
  • Dry rot can spread throughout your woodwork, making it more aggressive and destructive. Wet rot tends to be more localised and won’t spread to areas that aren’t sufficiently moist
  • There are several types of wet rot, but there is only one type of dry rot (serpula lacrymens)
  • Dry rot doesn’t need a constant source of moisture, but wet rot usually requires a consistent moisture source, so is commonly found in areas with leaky pipes or plumbing problems
  • If there’s a wet rot infestation, the wood will feel spongy and soft when touched

Is Dry Rot Damaging?

 If left untreated, dry rot can cause major structural damage because it can spread throughout the entirety of the wooden structure. This means if you have dry rot in the wooden structure of your house, you could be looking at a complete (and expensive) replacement of beams if left untreated. This is why it’s all the more important to be able to identify dry rot and stop it in its early stages.

Dry Rot Stages

There are several stages of dry rot, so there’s ample opportunity for you to diagnose the issue before it gets too serious.

  1. Spores - Like many types of fungus, dry rot starts off as spores. They will lay dormant on timber until there is enough moisture content in the timber to ‘activate’ the spores. Singular spores might not be visible, but a higher concentration of spores appear as brown/orange dust which can be mistaken for brick dust. Unless there is enough moisture or contact with timber, the spores won’t develop further.
  2. Hyphae - If you are able to identify the hyphae stage, you should be able to stop the dry rot before it becomes too serious. Hyphae are visible white/grey strands or patches that appear on the outer surface of the wood. They quickly infest the inside of the timber, so keeping an eye on the outside of your timber is key to preventing further destruction.
  3. Mycelium - If you fail to identify the first stages of hyphae, you will encounter mycelium. When the existing fungus has eaten through the timber, it will look for another source of wood to invade. In order to do this, the hyphae develop into mycelium which can take the form of a cotton wool-like substance or grey sheets.
  4. Fruiting body - The fourth and final stage of dry rot is the fruiting body. Dry rot prefers a dark and damp environment free from a breeze, but if these conditions change, the fungus will attempt to protect itself by creating a sporophore fruiting body. This looks a bit like a mushroom and appears grey or silver, but it can feature patches of purple and yellow. Its purpose is to release spores into the atmosphere in the hope they land in another suitable location so the cycle can continue.

Dry Rot Treatment

As with any problem, the longer you leave it, the more expensive it is to fix. If you think you might have a case of dry rot – or if you’re looking to prevent it – the first stage is to minimise the risk of damp in the home by installing proper ventilation and correcting any plumbing leaks and/or gutter leaks. This could be in the form of an extractor fan, or by ensuring you regularly open windows and allow good air circulation throughout the home.

Not only will this reduce the risk of dry rot (and indeed wet rot), but it will also prevent other types of damp that could be just as harmful to your home.

Depending on the severity of the issue, we would recommend removing and replacing the affected areas of timber as part of the next stage of treating dry rot. If the infestation isn’t too advanced and the structural integrity of the wood isn’t compromised, irrigating and sterilising the wood or masonry could be sufficient.

Do you Have Dry Rot?

If you think you might have a case of dry rot within your property, get in touch with our team to book a site survey and to discuss the plan of action moving forwards.

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