Identifying Dry Rot Signs, Symptoms, and How to Spot Them

Identifying Dry Rot Signs, Symptoms, and How to Spot Them

5 Sep 2023
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Preserving the structural integrity of your property is paramount for every homeowner. One of the most insidious threats that can silently undermine the solidity of your building is dry rot. Dry rot is a destructive fungal growth that feeds on the cellulose in timber, weakening it and potentially causing severe damage if left unchecked. 

In this detailed guide, we explore the signs and symptoms of dry rot and equip you with the knowledge to spot them early, enabling you to take prompt action to protect your property. Take a read to learn more.

Understanding Dry Rot

Before we dive into the signs of dry rot, it’s essential to understand what it is and how it develops. Dry rot is caused by a wood-destroying fungus known as Serpula lacrymans. Unlike wet rot, which requires higher levels of moisture, dry rot can thrive in damp conditions as low as 20%. It can travel through masonry and even plaster, making it a formidable foe. 

To identify dry rot in its early stages, keep a vigilant eye out for the following signs;

  • Surface Mycelium

Mycelium is the cotton wool-like white or grey growth that appears on the surface of timber affected by dry rot. This fluffy, fungal mass is a clear indicator of an ongoing infestation. It can spread rapidly and should be taken seriously.

  • Fine Cracks and Cuboidal Shrinkage

Dry rot can cause the timber to shrink and crack in a characteristic cuboidal pattern. These cracks, often accompanied by a deep reddish-brown discoloration, are significant tell-tale signs of dry rot’s presence.

  • Distorted and Discolored Timber

Infected wood may become discoloured, taking on a dark brown or rusty hue. Additionally, it may become distorted, losing its original shape and compromising its structural integrity.

  • Musty, Damp Odour

A distinctive, musty odour often accompanies dry rot. If you notice an unpleasant smell in certain areas of your property, it may indicate the presence of this destructive fungus.

  • White Hyphal Growth

Dry rot can produce thread-like structures called hyphae, which appear as white strands spreading across and through the wood.

  • Formation of ‘Fruiting Bodies’

As the dry rot fungus matures, it develops spore-producing structures known as ‘fruiting bodies’. These can take the form of flat, circular discs with a rusty red colour. When fully mature, they release millions of spores, contributing to the spread of the infestation.

  • Hollow Sound and Crumbling Timber

Tap the timber suspected of dry rot gently. If it emits a hollow sound or crumbles easily, it indicates a loss of structural strength caused by the fungus.

How to Spot Dry Rot

Dry rot can appear in various parts of your property, making it important to know where to look for signs of infestation;

  • Floorboards and Joists: Check for signs of fungal growth, cracks, and discoloration in wooden floors and structural joists.


  • Timber Skirting Boards and Door Frames: Inspect skirting boards and door frames for any visible signs of dry rot, such as surface mycelium or cracked wood.


  • Window Sills and Frames: Pay close attention to window sills and frames, as dry rot can develop in these areas, particularly if there are leaks or condensation issues.


  • Roof Timbers: Attic spaces and roof timbers are common places for dry rot infestations, so be sure to inspect these areas regularly.


  • Damp and Poorly Ventilated Areas: Dry rot thrives in damp and poorly ventilated spaces, so focus your attention on basements, crawl spaces, and areas with inadequate air circulation.

What to Do Next

If you observe any signs of a dry rot infestation, immediate action is crucial. You need to seek out a dry rot specialist who can conduct a comprehensive inspection and assess the severity of the infestation. The specialist can then devise a suitable treatment plan, which could entail the removal of the affected timber, application of fungicides, and precautionary measures to deter future occurrences.

Require Professional Dry Rot Treatment?

Here at Kenwood PLC, we specialise in dry rot treatment and emphasise the essential steps in this process. These steps include eliminating moisture sources, destroying fungal growth, and replacing compromised timber. Treating dry rot often demands special measures like irrigation, where we meticulously inject fungicidal preservatives into the affected masonry under pressure. 

Once the fungus is completely eradicated and moisture sources removed, our dry rot experts introduce new, high-quality timbers, ensuring they’re properly isolated from the masonry with adequate ventilation in place. For expert advice or to arrange a professional survey, don’t hesitate to reach out to us at Kenwood PLC. Call us on 01923 242441 or email us at

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