dry rot

Everything you need to know about dry and wet rot

Homeowners and property hunters fear the discovery of wet and dry rot… with good reason! Both types of rot can cause significant damage to structural timbers, and if left unaddressed this can compromise structural integrity.

To help you decide what to do if you think you may have spotted it, we’ve put together our guide to everything you need to know about dry and wet rot…

What is dry rot?

Dry rot is a type of fungus (Serpula Lacrymans) that grows on damp wood. It’s the most serious form of fungal decay owing to its ability to spread through a building, even through masonry and plaster. If the timber in your home becomes damp, with a moisture content over 20% then dry rot spores could germinate and spread their grey strands.

Once established, dry rot fungus feeds on the parts of the timber that give it strength.  It can survive without a source of moisture, owing to its ability to generate moisture from the timber it digests, leaving the wood weak and brittle. If the wood in your home is affected, it’s not difficult to imagine the serious and dangerous potential consequences for your:

  • Structural wall timbers
  • Roof frameworks
  • Flooring
  • Staircases
  • Skirting boards
  • Door frames
  • …any wood in your home!

Signs of dry rot

It’s essential to catch dry rot early before it has a chance to spread and cause significant and costly damage. Some signs you may have dry rot include:

  • A damp smell
  • Shrunk/warped timber
  • Cuboidal cracking across the wood
  • Dry, brittle wood that will easily crumble and break by hand
  • Spores – red/orange/brown dust
  • Hyphae – fine grey strands
  • Mycelium – white/grey ‘cotton wool’ on wood
  • Sporophore – the fruiting body that will release new spores, a red/rust/orange ‘fleshy pancake’.

Dry rot treatment

If you suspect dry rot, you need to act immediately. Arrange for a dry rot survey to determine how bad the damage is. A specialist will then be needed to remove the rot to a suitable extent, and carry out dry rot treatment on the adjacent structure.

They will first address anything causing damp e.g., leaking pipes or condensation. All the affected wood will then need to be removed.  With dry rot, the removal of timber goes beyond the extent of visibly affected timber, and adjacent masonry will also need to be sterilised with a high-strength biocide that penetrates deep into the masonry, as part of the treatment process.

Any remaining timber will be treated with specially formulated fungicides that will kill dry rot and stop re-infestations, preventing any further outbreaks of the fungus.

What is wet rot?

Wet rot is considered less serious than dry rot; it is the natural decay of wood when it becomes wet with a moisture content of 30-50% (higher than dry rot). Like dry rot, it is caused by one of a few fungi that thrive in damp conditions and consumes the timber.

Unlike dry rot, wet rot won’t spread beyond the damp area of wood, but that doesn’t mean you can simply ignore it. If structural timbers are weakened by wet rot, they can have their structural integrity weakened or even compromised.

Signs of wet rot

Some signs you may be suffering from wet rot include:

  • A damp smell
  • Damp timber
  • Dark brown stains on wood
  • Bleaching on wood (around the affected area)
  • Splitting/cracking along the grain of the timber
  • Visible fungus/mycelium strands
  • Wood that feels soft or spongy
  • Wood then caves in easily when you press it with a tool e.g. screwdriver
  • Wood that cracks/crumbles when dry
  • Flaking paint – you can test by pushing a knife into painted timber. The knife shouldn’t penetrate too deeply if you’re free of rot
  • Timber shrinkage/distortion/discolouration/weakness

Wet rot treatment

If you notice signs of wet rot, take action to find out what is causing the dampness and stop it!  Next, ask a wet rot specialist to come, determine the extent of the damage and type of fungus, and carry out wet rot treatment. They’ll remove all affected/damaged wood and carry out repairs before treating the whole area with an appropriate fungicide. Ensure any new timbers have also been pre-treated with a fungicide to stop any future wet rot fungus in its tracks. 

Should you buy a house with wet or dry rot?

Wet and dry rot can affect any property if the prevailing conditions for the fungus to thrive are present.

If your house survey reports the presence of wet or dry rot, your heart may sink. However, it doesn’t necessarily spell doom for your property purchase plans. Other than abandoning the purchase, you have three options:

  1. Continue with the purchase in the knowledge that there are potentially serious problems with the property that you will have to fix/pay to fix.
  2. Ask the vendor to remove the rot, carry out repairs, apply relevant treatment and supply certification that all work has been carried out to a satisfactory standard; where relevant covered by a long-term guarantee that transfers with ownership of the property.
  3. Get quotes from specialists to deal with the rot and ask the vendor to reduce the house price by that amount.

Get in touch

At Trinity Rose, our Chartered Surveyors have years of experience inspecting properties and checking for signs of dry and wet rot.

If you’re planning to purchase a property or have concerns about your own home, please get in touch to arrange a survey with one of our specialists.