wet rot treatment

Dry Rot and Wet Rot Treatment Guide

Buying an old property that has fallen into disrepair can be a great way to get a bargain in today’s housing market, but neglected properties often suffer from rot which will need treating before a home can be lived in.

This guide will teach you how to diagnose dry and wet rot, looking at the signs your house is infested and what treatment methods are available. There is a step-by-step tutorial on how to treat the rot, along with tips on preventing rot returning.

Tools and Materials


  • Chisel
  • Drill
  • Paintbrush/Sprayer/Scraper/Sealant gun


  • Boron Treatment in either solution, gel, paste or rod form
  • Plastic wrap
  • Wood filler
  • Spare timber
  • Dry rot paint (optional)

How To Diagnose And Treat Dry Rot and Wet Rot

1. Identify Rot

Dry Rot

Identify rot
  • Dry rot has white or grey root-like strands. These dry out and become brittle.
  • Sometimes rot forms sheets called Mycelium. Dry rot is either off-white, pale yellow or lilac.
  • Dry rot produces flat spores that are red in the centre with an off white surround. Dry rot spreads using these red fungal spores.
  • The final sign of rot is cracking across the wood. Large misshapen cracks indicate dry rot.

Wet Rot

damage caused by wet rot
  • Wet rot has three varieties. Coniophora puteana has dark grey/brown/black stands and stays flexible when dry. Fibroporia Vaillantii has thick white strands, while Asterostroma has thin white strands.
  • Wet rot Mycelium sheets are always bright white.
  • Wet rot produces tiny mushrooms that are beige and is caused by wood-boring weevils, identifiable by the fine sawdust they leave behind.
  • Wet rot has an earthy smell and will cause paint to flake off. The wood will be soft to touch.
  • Small cracked squares across the wood are the final sign of wet rot.

Pro Tip: Masonry can also be affected by dry rot. Check out this advice page from Permaguard for more information.

2. Choose A Treatment Method

The remedies for dry and wet rot differ slightly. Wet rot has an extra set of steps where the treatment needs to be applied to the surviving wood.

Boron treatment is easy to apply, safe for animals, and water-based which makes it odourless. It comes in a solution for large patches and a gel for heavily infested areas or places where extra water would be a hindrance. Using a large paintbrush, simply coat the area with the solution.

At PWS, we highly recommend N-Virol’s Boron Wood Preservative:

No products found.

Boron Epoxy paste and rods should be used in places where the timber will be permanently wet. The paste is squeezed into the gap left by rot and rods are inserted the length of the timber.

The treatment kills the spores and hardens the wood, preventing the rot from returning.

3. Remove Rot

hole in ceiling caused by rot

With a chisel, scrape out rotten sections of timber. If the wood is rotten through, cut out section with a hand saw. Drill evenly spaced holes in remaining timber to help the wood absorb the treatment.

If you have dry rot, skip ahead to step 7.

For wet rot, continue from step 4.

4. Prepare Remaining Wood

Drill evenly spaced holes in remaining timber to help the wood absorb the treatment.

5. Apply Treatment

Mix up solution according to manufacturer’s instructions and paint on with a large clean brush. Epoxy pastes will need to be spread on with a PALETTE KNIFE, or inserted using a sealant gun.

6. Let Dry

Leave to dry, covering with plastic wrap if the area will be exposed to moisture during the drying time. This is usually two hours, but check the instructions on the packet.

7. Replace Wood

If necessary replace rotted wood by inserting cut timber patches or using wood filler.

For wet rot, you are now finished. There is one more step for dry rot.

8. Prevention (Dry Rot Only)

window rot

Apply dry rot paint around affected areas to prevent spreading.

As long as dry and wet rot is treated, it shouldn’t pose a problem. It’s a nasty thing to deal with, but once the rot is removed and the wood treated as per the above instructions, it shouldn’t return.

Final Thoughts

Watch the following video for a close-up look at wet rot on a windowpane:

Rotten Window repair from wet rot

If you have found this guide helpful, please share on social media or leave us a comment below.

Leave a Comment

Your email address will not be published. Required fields are marked *