Can dry rot devalue a home?

Dry rot is a serious issue in a home and can lead to many problems while you’re living there, never mind during the buying or selling process. It’s one of the two main forms of rot we find in UK buildings, the other being wet rot. When dry rot spreads to unmanageable and dangerous levels, it can significantly impact the house price, driving it down. In this article, we’ll explore what dry rot is, how it affects house prices and how a home survey can help with the process.

What is dry rot?

Dry rot (Serpula lacrymans) is a form of fungal decay alongside wet rot. As the fungus grows, it eats through timber, feeding on the cellulose within. As it spreads, the wood dries out and begins cracking and splitting. It’ll also be noticeably brittle. Dry rot grows when humidity levels of between 18%-30% and poor ventilation combine to provide optimal growing conditions for the fungus. The spores actually surround us most of the time. They’re usually harmless – the problem arises when they settle on wood sitting in the necessary conditions to germinate.

The sooner you catch a dry rot infestation, the more cost-effective the solution. It’s not always the property-slayer it’s made out to be. However, in severe cases, you made need to commission considerable amounts of structural work to alleviate any problems. With an effective management plan, many people get by just fine. When looking for dry rot, remember that some areas of a house – usually the structural parts of walls – are basically impossible to see until you own it. It can also affect floorboards, joists, and any timber within a property. People often – perhaps rightly – point the finger at older houses when it comes to forms of rot and damp. This is because they have poor insulation, humidity control and ventilation compared to newer homes. However, rot can attack anywhere and at any time. It’s still important to be vigilant, no matter the age of your property.

What are signs of dry rot?

As you look through a house, check for these signs of dry rot:

Timber damage

Wood affected by dry rot turns darker. It’ll be dry, crumbly and brittle, experiencing distinct ‘cuboidal cracking’ – think of an old-fashioned paved street with different sized flagstones. It’s somewhat similar to that!

Spore build-up

As mentioned before, dry rot spores are all around us, harmless until they germinate. Small amounts of it are fine, but if you notice a considerable amount of rust-coloured dust, it could represent an active dry rot problem.


Hyphae are the long, silky-looking substances that grow from dry rot spores as they germinate. They grow at the tips and look somewhat like spider silk. If you see these, it usually means the dry rot is spreading.


As dry rot spreads from timber and it can’t feed on it anymore, it produces a substance that looks like cotton wool. At this stage, it’s crucial to get it treated as soon as possible.

Rust-coloured ‘mushrooms’

They aren’t mushrooms, but the rust-coloured fruiting bodies do look an awful lot like them. Visually extremely unappealing in your home, they appear when dry rot can’t grow anymore and needs to release more spores into the air to find more timber. The earlier dry rot can be treated, the better.

What is wet rot?

Although this article focuses on dry rot, we’ll briefly touch on wet rot here too. Wet rot is similar to dry rot, as may be clear, but forms from different types of fungi. Wet rot is a broad term for many different species, whereas dry rot is just the one, Serpula lacrymans. Perhaps the main difference between dry rot and wet rot is that the latter grows in humidity levels of 50% and above. These levels are notably higher than those required for dry rot. It doesn’t spread as quickly or infectiously as dry rot – it’s more localised. That being said, it still needs to be treated. Wet rot is usually caused by water leaks or weather penetration, for example:

  • Roof leaks
  • Rising damp
  • Penetrating damp
  • Burst pipes

How can I keep dry rot away from my home?

The best prevention for dry rot is adequate ventilation. In this country, where we usually average between 70% and 90% humidity, the air is naturally damp. For any wooden structures outside, there’s not much we can do about that. However, good ventilation can keep the spores from settling and prevent dry rot from taking root and growing. The wood used on your property should be kiln-dried, wherever possible, to reduce its moisture level to below 20%. Without sufficient moisture, the dry rot spores will struggle to germinate. Finally, you should constantly check and maintain all water- and weather-related aspects of your home. This could include:

  • Roof servicing
  • Water pipe servicing
  • Sealing decks

How rot impacts house prices

In severe cases, dry rot can cause serious structural damage when it’s spread to an unmanageable level, eating away timber. Most people aren’t keen to invest in a property like that, so the owner often struggles to sell. As a result, the asking price gets lowered, sometimes significantly.
There might be three choices for the seller:

  • Significantly reduce the advertised market price.
  • Fix the problem themselves before putting the house on the market.
  • Sell to renovation companies or individuals who will pay dramatically less.

Can a home survey help with rot?

Our trained and qualified RICS-regulated chartered surveyors have a keen eye for dry rot. During a home survey, they’ll visually inspect every area of the house they can and let you know if they find any. If you’re looking to buy a home with a known dry rot problem, it’s not necessarily a deal-breaker. During a home survey, our expert surveyors note down how serious the issue is likely to be. In their report, they’ll advise you as to how you could proceed. For a free initial consultation, you’re very welcome to get in touch with us.

Looking for a quote, or maybe you have a question? Get in touch today.

GB Home Surveys
4 High Street
Gloucestershire GL18 1AN

Registered in England: 02702789
Copyright © 2022 GB Home Surveys   |   Site by QBD