How to deal with dry rot and wet rot timber damage

wet rot

If you have ever bought a house before, you will know the importance of having a survey, but what if the report finds wet rot or dry rot?

What is it? How can it be dealt with? We, as a company, only really deal with damp in masonry, but we often get asked about other types of damp, so we wrote this for your reference and research.

We explore these two common forms of damp damage and how to fix it.

The problems of wet and dry rot.

These 2 main types of rot refer to damage done by forces of nature, mainly to the wooden parts of your home. Rotting wood and rotten timber are NEVER a good sign.

This can include floorboards or floor joists, roof joists and timbers inside the roofspace and any other wooden material that makes up the construction of your house.

Timber (“lumber” in USA) is a readily available, natural building material which has been used by man for 1000’s of years without much issue. It is versatile and can be employed in a multitude of uses in constructing or improving a home.

The problem nowadays with modern heating systems, insulation and double glazing, our homes don’t have the natural air circulation anymore, which is when problems can start.

What is dry rot?

Dry rot refers to decaying wood which is normally caused by a fungus that literally eats away at the wood, destroying it’s latent strength and tensile structure, meaning the wood softens and therefore loses it’s strength. If the affected wood is a load-bearing timber, such as in your roof, this is a very bad sign and replacement must be instigated as soon as possible.

Contrary to it’s name, dry rot is NOT dry at all, and needs moisture or damp in order to germinate and grow.

Dry rot affected wood. (C) Wikipedia

One of the most tricky things about this type of damage is that it often occurs in hidden places, such as under the floor or in the roof, so even if you have lived in the same house for 10 years and have no intention of selling, a periodic survey by a surveyor can at least bring peace of mind.

There are four main stages to dry rot infestation

Dry rot, like most causes of damp in the home, starts out as tiny spores in the air and can be spotted sometimes as an orange dust or powder on the wood. Regular inspections by a qualified timber contractor can be a lifesaver if the rot is noticed early on, and then treatment can take place which may save the wooden structure from further contamination, and/or expensive replacement of timbers.

The second stage of contamination, and only with sufficient moisture or damp present, is where the rot starts to grow into something like a fungus, which then germinate, grow and spread into the third stage, just as other types of damp multiply.

The fourth stage is where it starts to resemble a living plant or organic matter and the infestation then gets much worse and spreads much quicker. It is rare at this stage to be able to carry out a repair without replacing ALL the affected wood in the area.

Timbers affected by dry rot completely lose their strength and the wood can crumble away in your fingers.

brick house treated with waterproof coating

This may be a good time to have a look in the loft for signs of damp, or if you have a room inside that has a musty smell that just won’t go away, check under the floorboards, just to be sure, although bear in mind that can be a major job, so maybe only consider that if you are confident something is not right.

What is wet rot?

Timber damaged by wet rot. (C) Wikipedia

Wet rot is less common a problem than dry rot and is often caused by the timbers being exposed to above-average levels of moisture or humidity, accelerating the natural decay of timber, and is often caused by an external issue such as a structural problem or a leaking pipe.

Wet rot can be caused by a poorly maintained house, especially one where the exterior walls have little or no weatherproofing, perhaps with cracked render or porous brickwork, allowing the moisture into the home and into contact with the wood, causing the rot.

A specific weatherproof exterior wall coating on the outside of the house would solve this problem, coupled with treatment of the timbers after the walls have been weatherproofed from outside.

Wet rot is sometimes much easier to spot than dry rot and commonly affects wooden surfaces in more prominent places in your home. A good place to spot it would be the bottoms of doors and door frames or floorboards which feel “spongy” underfoot.

A faulty DPC (damp proof course) is often to blame for this type of damage as instead of the ground water stopping from rising up at the DPC, it carries on upwards and makes the floor joists and floor boards wet. An injected DPC is often the way to cure the damp rising but if the wood is badly affected it would need replacement.

damp proof course injection-machine

A damp proof course injection-machine

Also check for rot wherever moisture is common in your home such as under baths or showers and under the kitchen sink. Small leaks can, over time, turn into patches of damp wood which then rots.

What else can damage the wood in my house?

One problem some of our regular readers over in the USA have is damage by termites or other bugs, often as most homes in the USA are wholly wooden constructed, although beetle damage does occur here in the UK and your local timber care contractor can also advise you on getting rid of the bugs and fixing the wood so they don’t come back.

Another, less common, problem with wooden houses is settlement or subsidence which we discussed earlier this year, HERE.

What to do after finding any rot in your home

We would strongly advise contacting your local timber care specialist and ask their advice. They will probably suggest a home visit to assess the problem. If your house has structural damage from wet rot and it is unsafe, they will be the people to alert you to that.

However bad the issue is, in most cases dry or wet rot CAN be treated, usually in the form of removing and replacing the wood. Afterwards it is good practice to have all your timbers professionally treated to avoid a recurrence of the problem.

I hope that this article has been helpful to you and thanks for reading.


Please note this article is for education and reference ONLY and our company does NOT offer repair to dry or wet rot but some of the timber care and wood preservation adverts shown on this page, and provided by Google, may do so. We are not responsible for external websites accessed through our own site. Thanks.

Picture credit: Main photo from

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