Meruliporia incrassate - Brown Rot Fungus

meruliporia incrassate- dry rot fungus

Meruliporia incrassate is a type of wood decaying fungus  causing so called “dry rot, or true dry rotof relatively dry timber structures. Meruliporia incrassate is known under several other synonyms such as Poria incrassata and Serpula incrassate. Meruliporia or poria mainly affects building in the North American region and is very rare in the United Kingdom.


The fungus has the ability to attack relatively dry wood by decomposing cellulose and hemicelluloses leaving  a relatively brittle matrix of modified lignin. Meruliporia can cause dry rot because it can provide its own source of moisture which it draws from the surrounding structure or ground. Meruliporia incrassata require about 28% of moisture in the wood to start the decay but once the dry rot has establish itself the moisture content of the wood can fall below 20% and still the decay would progress.

Meruliporia incrassata, an orange coloured mushroom shaped macro fungus. Meruliporia can create large, semi-tough water-conducting roots called rhizomorphs which transport water by capillary action from a constant source (usually damp or wet soil) to dry wood in a building, wetting it sufficiently to support decay. As poria spreads thorugh the structure liquid is transported along the rhyzomorphs to the point of active growth. The transported water helps to wet adjacent wood and thus help further decay. The danger of meruliporia lies in the fact that water damage is not neccessary for this fungus to destroy the wooden structure, warer is carried out by the fungus from a point of entry and can spread across the whole building. Poria is known to be the most damaging wood-decaying fungus of houses.

meruliporia incrassate- dry rot fungus

Meruliporia can be relatively easily identified by the presence of rhizomorphs which looks like a barkless root and smells like a mushroom if broken open and by the appearance of the fruiting body and the dark coloured spores it produces. Rhizomorphs can be usually found under the floor boards, undergroung passages, often crawling along foundaitions walls and sometimes in partition walls where it can spred undisturbed over large areas.

The roots can penetrate into internal ares through the tiniest of openings and they usualy foolow the cable or plumbing runs. Meruliporia does not have the power to activelly penetrate hard surface andtherefore the simplest of prevention measures are very effective against poria attack. When poria is removed all openings need to be checked and tightly sealed to prevent future penetration of this fungus.