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Dry Rot – Causes, Identification & Solution

What is Dry Rot?

Dry rot is a type of fungal timber decay known as Serpula Lacrymans. It occurs when wood becomes too wet with a moisture content of over 20% and the wood-destroying fungus attacks the timber.

Dry rot is the most serious form of fungal decay. Dry rot fungus is very destructive as it spreads across masonry and destroys all timber in its path including structural timbers, skirting boards, door frames, and flooring. It affects all types of properties, new and old, and can be detrimental to a property if left untreated as the fungus can weaken the structural integrity of a building and cause it to collapse.



Dry rot occurs when airborne spores come into contact with damp timber that has a moisture content of over 20%. These spores then germinate and sprout grey root hyphae strands. The hyphae grow into mycelium which covers the timber in a thick cotton-wool like substance. The fungus eats the wood and sucks the moisture from it, leaving it weakened. The fungus then advances into a fruiting body known as sporophore which sprouts more spores to continue the life cycle.

Dry rot spores develop into the wood-destroying fungus as a result of damp timber and the fungus thrives in moist, damp, poorly ventilated conditions. There are many reasons why timber could be damp in the home, including penetrating damp, condensation, leaking pipes, faulty drainage, broken roof tiles, or a leaking washing machine, and thus creating the ideal environment for fungi growth.



The longer dry rot is left untreated, the greater damage it will cause to your property, so it is important to identify the signs as soon as possible, and early detection is key to eliminating the fungi. Look out for these key signs:

  • Because the fungus likes dark and damp conditions, dry rot is often found in non-visible areas such as under stairs, in lofts and attics, in flooring, and behind plaster.
  • Shrinking and warping timber caused by the removal of moisture from the wood.
  • Cuboidal cracking across the grain of the wood.
  • A damp fungal smell.
  • Dry, brittle, and fractured wood that will crumble and break by hand.
  • Depending on what stage the fungus is in its life cycle, it will present itself in different forms:
    • Spores – dry rot begins as a red-rust, orange, and brown-coloured spore dust.
    • Hyphae – once spores come into contact with wet timber, the spore will germinate to produce hyphae which are identifiable by fine grey strands that grow through the timber.
    • Mycelium – hyphae multiply and generate mycelium growth which is characterised by a white or grey cotton-wool-like substance that spreads across masonry in search of wood for food.
    • Sporophore – this is the fungus’s mushroom fruiting body. It is rust-red and orange in colour and looks like a flat fleshy pancake. The sporophore releases new spores in order to begin the life cycle of the fungi again.



If you have identified any of the signs of dry rot in your property, you should take action as soon as it is spotted and have a dry rot survey carried out to assess and inspect the full extent of the damage. If your surveyor finds that dry rot is present, you will need to seek a dry rot specialist to remove the infestation. They will take the following steps to treat dry rot and rectify your home:

  1. To eliminate fungal growth you need to first stop the source of the moisture. This can be any number of things including a leaking drainage pipe, condensation, faulty roof tiles, damp walls, a leaking shower tray or washing machine, penetration damp, or rising damp. Once you cut off the moisture, this prevents the fungus from feeding and growing.
  2. Next, remove all infected timbers and damaged wood in the affected area including any skirting boards, panelling, and flooring.
  3. Then, treat the existing structural timbers with a fungicide treatment to form a protective barrier against further fungi growth.
  4. Finally, replace the damaged wood with pre-treated timbers to prevent further infestation and eliminate future spores from germinating.

As a further preventative measure, you should ensure that the area is well ventilated using a dehumidifier to completely remove all moisture and prevent growth.


Book A Dry Rot Survey with Allcott Associates Today

If you identify the signs of dry rot in your property and think that it may be present in your home, get in touch with Allcott Associates today for further advice or book a survey and our trusted surveyors will carry out a damp report that will check for timber decay and dry rot, assess the damage, and recommend the best course of action to remove the fungus, prevent further growth, and rectify your home.

Or contact us for more information: | 0333 200 7198