Spotting the early signs of rot in your wood

There are two common types of wood decay that we find in our buildings – wet and dry rot. Both can cause serious damage to buildings, which can be prevented if you spot the signs early and call in the experts.

First of all, let’s explain the difference between wet and dry rot:

Wet Rot

Wet rot is a fungal decay that occurs in timber with a high moisture content (usually above 20%). It’s caused by several species of fungi, most commonly Coniophora puteana.
Wet rot thrives in persistently damp conditions, such as leaking roofs, plumbing leaks, or poor ventilation. The fungus breaks down the wood’s cellulose, causing it to soften, crack, and lose strength.

 

 

 

 

 

 

Dry Rot

Dry rot is a much more serious form of fungal decay, caused by Serpula lacrymans. Despite the name, dry rot still requires moisture to start, but it can spread into relatively dry wood once established.

Dry rot starts in damp, poorly ventilated areas. The fungus can travel through masonry and spread to other wood, even if the wood is not very damp.

 

 

 

 

 

 

 

Key Differences

 

Spotting the signs

• Changes in the wood: With wet rot, wood darkens and feels soft and spongy sometimes with small cuboidal cracking. Whereas with dry rot, wood shrinks, cracks into large cubes, and becomes brittle. Fissures may develop. These are signs that the cellulose structure is breaking down

• You may also see Dark or Discoloured Patches. Wet rot often begins as darkened areas on wood, especially in places exposed to moisture like basements, bathrooms, or near leaking pipes.
• Flaking or peeling paint: Paint or wallpaper may blister, peel, or crack due to moisture trapped beneath the surface.

• Musty or Earthy Smell: A persistent musty odour is a strong indicator of fungal activity and moisture entrapment, often a distinctive mushroom-like smell.

• Visible Fungal Growth: Look for cottony or silky textures, or coloured spores (yellow, white, purple) on the wood surface.
  • Greyish-white fungal growth, sometimes with yellow or lilac tinges can appear with dry rot.
  • You can see rusty red dust (spores) nearby.
  • Fruiting bodies (mushroom-like structures) may appear.

Treatment for wood rot

The first step is to identify the source of moisture. This could be a leak, poor ventilation or even rising damp. If it’s a leak, get it fixed to avoid recurrence before you start to treat the rot.

Then it’s time to call in the professionals for a proper diagnosis.

At Kenwood, we survey the area and come up with a plan to remove affected timber and apply fungicidal treatment to the remaining timber to kill fungi and prevent recurrence. Where masonry is affected, treatment of the brickwork may be required in the form of sterilisation and / or irrigation to the walls.

Irrigation is the term used to describe the eradication of Dry Rot from masonry and involves drilling the masonry and injecting a fungicidal preservative to the walls under pressure. Kenwood fungicidal biocide is used to sterilise the surfaces of masonry and the oversite.

Following the eradication of the fungus and removal of the moisture sources during the treatment, new timbers can be introduced, ensuring isolation from masonry with physical barriers and adequate ventilation to the floor voids.

The final step is to improve ventilation. Where floor voids cannot be adequately ventilated, replacement in concrete may be required but in other cases, we can help with automated systems that work are designed to improve ventilation and eliminate condensation problems – whether in a single room or across an entire property. We also offer a hassle-free health check service where units are service annually and properties are inspected.

See Condensation Control for more information