Dry Rot

What is Dry Rot?

Dry rot is one of the most serious forms of timber decay found in buildings. Also known as Serpula lacrymans, dry rot is a brown rot that thrives in damp, poorly ventilated environments and feeds on the cellulose in wood, breaking down its structure and leaving it weak, brittle, and crumbly. Unlike wet rot, dry rot can spread rapidly across masonry and other materials in search of new timber to attack, making it particularly destructive if left untreated.

Dry Rot Characteristics.

Early signs include cracking or shrinking wood, a musty smell, and the appearance of a white or grey cotton wool-like growth or orange, rust-coloured spore dust. Over time, dry rot can compromise the structural integrity of floors, joists, and beams, leading to costly repairs and safety risks. Dry rot shows in decayed timber as a dull brown colour with deep cracks along and across its grain known as cuboidal cracking. The timber will be light in weight and crumble between fingers.

Dry rot has a life cycle of four stages;

Fruiting bodies: Tough, fleshy and pancake looking, often a large rusty-red mushroom, with white or grey edges. Dry rot produces a fruiting body when light activates mycelium.

Spores: Usually harmless without the conditions for dry rot and very common. Spores may settle as a fine layer of reddish-brown dust on horizontal surfaces which can be a sign of a fruiting body nearby.

Hyphae/ Strands: Spores produce hyphae when they are in contact with timber in damp and poorly ventilated conditions. Strands are white or grey and branch out. They can be quite thick and are brittle when dry.

Mycelium: Silky white sheets or cotton wool-like white cushions with patches of yellow or lilac when exposed to light, and grey in ventilated areas. Mycelium is produced by dry rot as it spreads across damp timber or masonry searching for new food sources.

Wet Rot

What is Wet Rot?

There are many fungal species causing wet rot, and the same remedial treatments are required for all of them. They cause a darkening of the timber known as brown rot, or a bleaching of the timber known as white rot. The most common fungi are Coniophora puteana (known as cellar fungus) which is a brown rot often caused by water leaks onto timbers, and Fibroporia vaillantii (known as mine fungus) which is a brown rot and is commonly found with wet timbers in areas of high temperatures. Unlike dry rot, wet rot tends to stay confined to the damp area and doesn’t spread aggressively, but it can still cause significant damage to structural and decorative timbers over time. Wet rot thrives in persistently damp conditions, so identifying and eliminating the source of moisture is key to stopping the problem. While less aggressive than dry rot, wet rot can still weaken floorboards, skirting, joists, and window frames, eventually leading to safety issues and costly repairs if ignored.

Characteristics of Wet Rot.

Wet rot fungus first develops as hyphae which can be brown or white, which further in its life cycle develops into mycelium. Wet rot can produce a musty smell, and small fruiting bodies. Timber can darken or lighten with cuboidal cracking depending on the wet rot, and its cracks are usually less deep than those of dry rot.

Blue Stain In Service

What is blue stain?

Blue stain in service is a fungal infection which has many species including Aureobasidium pullulans and Cladosporium spp. It cannot grow in waterlogged timber or timber below 20% moisture content. It acts by hyphae penetrating cell walls of timbers and feeds on cell contents but not on the woods substance, so it does not cause a structural impact, but certainly an aesthetic impact.

Characteristics of blue stain in service.

Blue stain fungi can cause a distinctive blue or grey discolouration in wood. It can appear in blotches of spots or streams but does not produce a fluffy growth like mould. It grows in warm and damp or humid environments. It damages the coatings of timber through its growth. Dark hyphae and fruiting bodies can be present, and staining penetrates deep through the timber and cannot be removed by surface planning.

Timber Preservation

When assessing whether timber preservation is appropriate, we carry out a detailed inspection of all wooden elements in the property, including structural beams, joists, floorboards, and furniture. We look for signs of damp, fungal growth, insect activity and general timber condition, taking into account the age of the wood, its exposure to moisture and its role in the building’s structural integrity.

For our clients, this assessment provides a clear understanding of potential risks and highlights areas where preventative action can save significant costs and disruption in the future. Once timber is identified as needing protection, we apply specialist preservative treatments designed to penetrate deeply, preventing fungal decay and deterring insect infestations.

In addition, we advise on long-term measures such as improved ventilation, moisture control and regular monitoring to maintain timber health. This approach not only safeguards the structural and aesthetic value of the property but also gives clients peace of mind, knowing their timber is fully protected, durable and less likely to require costly repairs down the line.