Identifying, Treating and Preventing Wet Rot

How to identify wet rot.

  • You will see fungus growing on the timber and the area may look darker.
  • Wood affected by wet rot feels soft and spongy, even through paint and will easily crack and crumble into fine particles.
  • You may notice a damp musty smell, look for damaged or flaky paint. However, even if the paint is not damaged and you suspect wet rot. Try pushing a thin screwdriver into the wood, if it goes in easily up to the handle, it's a sign of wet rot behind the paint.
  • Preventing Wet Rot. Keep damaged painted areas touched up, if the finish is damaged the risk is increased, fix leaking joints and pipes.
  • More about Wet-rot on this page.


What is Wet rot.

The most common wet rot we find in the home is the brown variety known as Cellar Fungus.

Wet rot is simply the wood decaying naturally because of moisture. It is almost always caused by a structural problem, a damp wall, poor or damaged paint work or simply water collecting on the timber. The cause must be sorted when the timber is treated for wet rot or it will reoccur.

Where are the areas in a house most at risk from Wet rot.



 The areas most at risk from Wet rot are;

  • Check window and door frames, for signs of rot.
  • Timber in the roof is at risk where there is roof damage allowing rainwater to run onto the roof timbers. 
  • The bottom of Door and Window frames are favourite spots where water collects, also walls and floors suffering from damp. The paint may look good, but wood under the paint may be rotting. Check by pushing a thin blade or screw driver into the wooden frames. If the blade is difficult to push in its probably OK, but if it goes in up to the handle, you probably have Wet rot in the wood.
  • Timber with Wet rot will feel spongy through the paint when you poke it. Dry timber will easily crack and crumble into fine particles.

How to prevent Wet rot getting into timber.

Preventing Wet rot.


 Paint all external timber frames, look for damp walls and sort the problem, could be the damp proof course is missing or damaged. A roof tile may have slipped, if you find or suspect Wet rot ask for advice as the symptom may be just a sign of a bigger problem.

Make sure that any soil and other debris is cleared away from around the bottom of timber frames.

Check Wet rots favourite places. These are under the kitchen sink, bath, shower, washing basins, toilet and behind the washing machine. These are places where a small leak from either a water supply or drain could go unnoticed for a long time.

Treating Wet rot. 

First of all treat any structural problem, there is no point in repairing the damage to the timber if it is going to reappear. 

If you are into Diy, I have listed the Wet rot products I use for Hardening the rotted wood, filling the affected area and a Wet rot treatment for the repair and importantly the surrounding timber later on this page.

How to repair wood damaged by wet rot

Fixing wet rot damage.

  • Fortunately, wet rot rarely gets to the stage of structural defects and can be treated by fixing the source of the damp problem and drying out the affected timbers. It is essential to make sure that you stop all leaks, drips and damp and treat all the affected areas with Wykabor 10 or similar or the wet-rot problem will return.
  • If wet rot occurs in structural timbers such as roof trusses and floor joists, ask for expert advice. In other areas, the rotten wood can be removed and replaced. Fairly small areas can be cut away and filled with wood filler, or a new piece of timber can be fitted.
  • This ronseal wood filler is the one I use it can be used to fill the damaged area once it has been cut back to sound timber. And the new surface of the wood treated with a suitable primer.
  • After the repair has dried out. If there is any doubt that the damp source problem has been sorted out, treat the filled area and adjoining timber with a good wet rot preventative (I recommend Everbuild) before redecorating.


D.I.Y. TIPS for repairing wet rot damaged wood.

  • First Poke or cut out the loose wood. Then, use Ronseal Wet Rot Wood Hardener that penetrates deep binding and hardening the decaying wood, to provide a solid base for wood filling. I use this stuff so I know that it is good. It soaks into the wood and sets hard, making filling repairs much easier and lasting.
  • Next Fill the cut out area with the ronseal wood filler described above.
  • Last Treat with Everbuild EVBLJCR05 5 Litre Wood Preserver wood treatment and preserver, its low odour with fungicides, algaecides and Permethrin to actively kill and protect against all known wood wet rot.
  • Penetration and effectiveness is greater than ordinary wood preservation products, it is fast drying and non flammable and application to wet timbers is possible.
  • Read the instructions.