Dry rot can turn strong wood beams, joists, and floorboards into crumbling ruins. It spreads quickly, and if not caught early, it can lead to expensive repairs—removal alone can range from £1,000 to £5,000, plus the cost of fixing the damage it’s caused.
But if you spot it early, you can save a lot of money. The fungus thrives in warm, damp, dark, and poorly ventilated areas. It’s often found in older homes but can also affect modern properties. If you notice any signs of rot in your home, it’s best to act fast and treat it.
Find out about the causes of dry rot, how to spot it, and how to handle it effectively.
What causes dry rot and how to identify it
Dry rot is caused by fungi that attack damp wood. If left untreated, it can spread to masonry and plaster, threatening your home's structure. Despite its name, dry rot occurs in damp conditions. So, it can be caused by high condensation levels or water coming into your home from the outside, like rising damp or leaks.
The key signs of dry rot include:
- Shrinkage
Wood may shrink and crack in a rectangular pattern. - Appearance
In dry conditions, it may show as a grey skin with yellow and lilac patches. In humid conditions, it appears fluffy, like cotton wool. - Fruiting bodies
Look for flat, fleshy, pancajke-like mushrooms that or brown or orange. These can release over 50 million spores per minute.
How to remove dry rot
- Remove infected wood
Start by removing any wood that has dry rot. You’ll need to contact a professional to help, especially if the problem is severe.
- Replace healthy wood
It’s recommended that you remove healthy wood within a metre of the infected area and treat new timber with a fungicide.
- Treat other timber
Protect other structural wood to avoid any future infestations. - Address masonry affected by dry rot
If the rot’s spread to your brick or stonework, remove affected plaster and mortar until you reach a metre beyond the last visible mycelium (fungal growth). - Improve ventilation
After repairs, make sure the room’s well-ventilated to dry out damp spots. Keep curtains open to let in natural light and consider using a dehumidifier to keep humidity levels low.
Preventing dry rot in the long term
To stop dry rot from coming back, it’s key to deal with the cause of damp. The fungus thrives in wood with a moisture content above 20%.
- Spot the damp sources
The most common causes are condensation and rising damp. Condensation affects many of our homes in winter; use extractor fans and heat every room evenly. - Look for rising damp
This happens when moisture rises through walls, often seen in older homes without proper damp-proofing. Check for tide marks or a salty-looking residue just above your skirting board. - Check for leaks
Look around your home for leaks from pipes, broken gutters, or appliances. And clean your gutters – ideally twice a year – to stop them overflowing.
Taking care of any moisture issues will make for a less hospitable environment for dry rot.
