When it comes to damp problems in the home, one of the most prominent issues is how the damp affects timber. Identifying wood rot, whether it is dry rot or wet rot, can vary in difficulty. This is primarily because of the vast range of different fungi which can thrive and grow on moist timber.

Whilst understanding the specific species of fungus affecting your timber might seem unnecessary, identifying wet rot or dry rot is actually a big part of the treatment process. Not only is it important when deciding on the most effective treatment, but it’s also essential to understand the size, depth and extent of the timber damage. As different wood rots have different effects on the timber where they grow, it’s important to have a strong knowledge of the signs and symptoms that are associated with each common wood rot species.

As damp proofing specialists who have been operating for over 15 years, the team here at Garratt’s Damp & Timber are experienced in identifying and treating wood rots of all shapes and sizes. Our qualified surveyors can quickly and effectively assess the situation in your property, advising you on the best course of action.

Using this knowledge, we have compiled a detailed guide on how to identify dry and wet rot. This way, you can easily understand the extent of your problem and act accordingly to keep your timber safe and stable - our comprehensive guide has all the answers you need.

If you would prefer to speak to a professional, please don’t hesitate to get in touch and book a survey. Our team are more than happy to help.

Identifying Rot Timber attacked/Growth Damage                               Signs                              
Brown Rots: A category of dry and wet rots


  • Depending upon the species, both hardwoods and softwoods can be attacked
  • The appearance of the rot varies according to the individual species
  • See below for further details relating to individual species
  • Feeds on the timber’s cellulose and leaves the lignin intact
  • The timber will become darker due to this method of feeding
  • Timber shrinks and cracks, causing the cuboidal cracking that can be seen in the picture to the left
  • Cuboidal cracking
  • The size of the cube will vary depending on the type of wood that is affected
  • Darkening of timber which is easier to observe on lighter woods
White Rots: A category of wet rots
  • Attacks both hardwoods and softwoods depending on the species
  • The appearance of the rot varies according to the species
  • See below under the individual species for timber attacked and the appearance of the growth
  • Feeds on the timber’s cellulose and lignin
  • Timber will become fibrous either internally or on the surface
  • Timber will take on a lighter colour due to lignin loss
  • Fibrous texture both on surface and within the timber
  • Lightening of the timber
Dry Rot

(Serpula Lacrymans)

  • Softwoods are most commonly affected by dry rot. Serpula Lacrymans is the only species of dry rot
  • Silky grey appearance with patches of lilac and yellow
  • S. Lacrymans has an easy-to-peel mushroom-like skin
  • The integrity of the timber is threatened due to feeding activity
  • The loss of strength in the timber may result in the need to replace affected sections
  • Large and deep cubes formed by shrinkage
  • The surface of the timber is unsound
  • Silvery, grey skin with lilac and yellow patches. Fawn or reddish brown areas are also possible
  • A white cotton wool-like growth may be present in more humid situations
Cellar Fungus Wet Rot

(Coniophora Puteana)

  • Both hardwoods and softwoods are attacked
  • Features a dark brown through to black sheet-like appearance
  • Fine brown strands may be seen emerging from wood
  • Cuboidal cracking of the timber
  • Rot often affects the internal structure of the wood leaving a thin but sound surface skin
  • The timber may show a slight yellow colouration in early stages
  • Dark brown to black sheets of fungus
  • Fine brown threads emerging from the wood
  • Cuboidal cracking
  • Darkening of affected areas of timber
Mine Fungus Wet Rot

(Fibroporia Vaillantii)

  • Mine fungus attacks softwoods
  • The main body of growth is white with light orange patches
  • White, coarse strands which are flexible despite their thickness
  • Cuboidal cracking to timber but not as deep as with dry rot
  • White, often fern-like growth, with light orange patches on the body of the growth
  • Cuboidal damage to timber
  • Coarse, white strands
  • Darkening to affected areas of the timber
No Common Name Wet Rot

(Phellinus Contiguus)

  • Both hardwoods and softwoods are affected
  • The growth resembles a rough chamois leather in colour and appearance
  • Tufted growths of light brown material can often be seen with P. Conitguus
  • The timber will be degraded and appear fibrous
  • Slight bleaching of timber colouration
  • Will attack external masonry
  • Appearance like chamois leather
  • Timber takes on a stringy, fibrous nature
  • Light brown tufts of growth
  • Lightening of the colour of timber
No Common Name Wet Rot

(Donkioporia Expansa)

  • Only hardwoods are attacked, most commonly oak
  • A thick, reddish-brown growth that may exhibit droplets of dark brown liquid
  • No strands will be noted with D. Expansa
  • The timber will be degraded and appear fibrous
  • Slight bleaching of timber colouration
  • Internal damage to timber is common
  • Thick reddish brown body to fungus
  • The timber exhibits a coarse, fibrous appearance
  • Occasional appearance of dark liquid droplets
  • Slight bleaching of wood
Oyster Fungus Wet Rot

(Pleurotus Ostreatus)

  • Panelling and boards like chipboard
  • Steel to fawn coloured mushroom-like main body
  • Woolly mat-like white growth can also be present
  • No strands are noted with this wet rot
  • Loosening or separation of the wood chips used in the board’s construction
  • Lightening to the colour of the wood products attacked
  • White, woolly mats of growth
  • Sometimes a mushroom-like growth with a steel-blue to fawn colour will also be present
  • The timber may appear lighter in colour
No Common Name Wet Rot

(Asterostroma spp)


  • Only softwoods are attacked
  • Thin grey to pink coloured sheets of growth
  • The strands associated with this rot are also grey to pink in colour, generally thin and quite long
  • The timber will take on a coarse, fibrous appearance common with many white wet rots
  • Timber will appear well aged and weathered
  • Thin pinky-grey body to growth
  • Thin pinky-grey strands that may also extend over damp masonry
  • Timber will appear fibrous and weathered


The following wet rots will not affect timber but do indicate damp conditions that may lead to serious fungal attacks in the future.

Ink Cap Fungus Wet Rot. Coprinus Domesticus

Ink Cap Fungus

Ink Cap fungus is sometimes referred to as plaster fungus as it is often seen growing from plasterwork

  • It may also grow on other substrates but it does not harm timber
  • It is indicative of very damp conditions that may lead to the growth of other timber attacking rots

Elf Cup Fungus Wet Rot. Peziza Spp

Elf Cup Fungus

  • Elf Cup fungus grows from carpet, brick, mortar, plaster and many other substrates. However, it does not harm timber
  • Like Ink Cap, it is indicative of very damp conditions that may lead to the growth of timber attacking rots further down the line

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