Can you identify Dry Rot, without a fruiting body to look at? here’s one way…..snap crackle and pop.

Dry Rot has perhaps the most striking of fruiting body’s –  brackets or plates of lovely convoluted and rust coloured sporophores’ which are unmistakable.

Dry Rot fruiting body close-up

However, only a mature infection will produce such handy nameplates and sometimes they’ve been removed or are hidden from view.

Dry Rot fruiting body growing across the underside of a timber floor

The video is one I shot the other day in a semi-derelict house in Leeds.  Dry Rot has had a field day in the past, due to a pipe burst (no drying done).

The infection has slowed to a snails pace, as the timbers have dried somewhat and the only fruiting body’s are under the floors; out of sight.  As it happens they’ve shrivelled up too so the bright rusty colours seen above are not there.

There is plenty of fungal growth though and some is quite dry.  There are decayed timbers too. This is the thing I wanted to point out to you; unlike wet rot mycelium, Dry Rot strands are brittle when dried.  I did have a handful of strands from a Fibroporia outbreak in a jar in the office and though these were years old, they were as flexible as cotton twine. Fibroporia can produce spectacular fugal growth and is miss-diagnosed as dry rot more than anything else.



As you will see and hear in the video, the Dry Rot strands snap easily because this part of the infection has dried out.  This is a handy tip for surveyors, because even if this was the only bit of fungus you found – it narrows the species right back to Serpula lacrymans; The Dry Rot we know and love.


Some diagnostic pointers on Dry Rot – by Bryan Hindle CSRT CSSW


The effects of the decay on the joinery in particular is also a great pointer.  See how the skirting curves and bends? All the cellulose contained in the wood is extracted by the Dry Rot, leaving the lignin behind.  The removal of these sugars destroys the longitudinal strength of the wood; hence the cuboidal cracking. The brown lignin is left; confirming the decay organism as a ‘brown rot’.  Whilst there are plenty of Wet Rots in the brown rot category, only Dry Rot has strands which are brittle when dried and bends and curves the joinery in such spectacular fashion.  Cubic cracking will happen with wet rots too, but it is much less well pronounced and tends to be finer and the cubes smaller.

I hope you find this useful…now go find some.


Dry Rot.


  1. Nice one Brian.

  2. These items are so very interesting and helpful, and really tell it like it is – thanks all

  3. Brian, This is a great video. I carried out a survey last week in a well presented and dry 1920s semi. recently decorated, newly finished bathroom, new double glazing etc. Much to my surprise the dry timber window cill in the bathroom was badly cracked (cuboidal) I took out a section to reveal strands of fungal type growth. I realized this was dry rot but where was the fruiting body. On closer inspection it became clear that at some time in the past the WC had been located below the same window. The cast iron soil pipe branch from the absent WC was still entering the wall but had been plastered over. It is not known whether it had been properly term inated and sealed. If left open could this be the location of the moisure feeding the fruiting body? It will need further investigation by the owner/buyer. Do you have any advice or contacts that could do the remediation work? Many thanks

    • Dry Rot says


      Thank you for your comment, I’m glad you found the video useful.

      Any persistant leak could feed a dry rot outbreak and should be found and stopped. A fruiting body isn’t the real heart of a Dry Rot outbreak; merely the end product. It doesn’t need feeding as such, it is manufactured from nutriants absorbed from wood and is often produced when an outbreak is maturing or is suffering stress, such as when things start to dry out.

      The real damage is done by the fungal hypha, which are in the wood and can grow behind plaster and in the cavities of masonry.

      The crucial thing is moisture – dry the wall and timber and the rot will die. If you were in Yorkshire I’d be on my way over to take a look, however as your in Hampshire try the Property Care Association web site. There’s a handy ‘find a member’ widget which works really well, whether you need a contractor or an independent consultant. There’s a link to the PCA on the right.

      Thanks again for looking in. Let me know if I can help in the future.

  4. Hi Brian,

    I was wondering whether you can tell me how i would be able to differentiate between dry rot mycelium and fibroporioa? (they both seem to look the same)

    • Dry Rot says

      Hi Billy,

      I can see why you’d be worried. However in practice it’s not as hard as you think. Fibroporia is usually very white and if you have the time just gently peel off some and dry it in the airing cupboard overnight. If you can still ball it in the palm of your hand without it crumbling and snapping then it’s a wet rot mycelium. Whilst some wet rots produce ‘strands’ Fibroporia is the most prolific, so if there are is loads of stringy white mycelium, which doesn’t dry to a brittle material, it’s probibly Fibroporia.

      Howeverr, don’t get too worried; as long as it’s not Dry Rot (which you can easily diagnose), it doesn’t in practice really matter which wet rot it is – you treat them all the same way. If in doubt as to which wet rot it is, I’d recommend that you just identify it as a wet rot species; that way you’re being honest and accurate and won’t look a fool if someone identifies it scientifically as another similar, but different species.

      Dry Rot.

  5. Hi Eileen,

    You should always get professional advice when dealing with dry rot. Find a local PCA member via the PCA web site. Identifying and mending the moisture source is crucial to success.


  6. Hi Nigel,

    Sometimes when a wall is treated with biocide it will ‘salt’ as it dries. To test if it is salt just scrape a bit off (gloves please) and drop it in a glass of water. If it dissolves it is salt – if it just stays as strands then its mould or fungus. If it is fungus don’t panic yet – when dry rot is under distress it will try to grow but as long as the source of the original moisture is rectified it is doomed. The treatment just helps it along the way…


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