How do you Identify Dry Rot?

Dry rot is an aggressive form of wood-decaying fungi that can cause severe structural damage to buildings by weakening the timber used throughout the property. Dry rot will attack timber and cause it to lose its structural integrity, meaning that floorboards, joists and other important timber components of a property will decay and crack.

Our guide has been designed to help spot the signs of dry rot, determine what is causing the problem and help reduce the potential costs associated with repairing dry rot problems.

If you think your property has a dry rot problem, we would recommend a professional damp and timber survey to be conducted. This is vitally important in order to fully investigate the extent of the damage and the source of moisture causing the problem.

Rentokil Property Care have a number of CSRT and CSTDB qualified surveyors who are experts in dry rot identification, and will provide you with detailed recommendations for treatments, if required. We are Property Care Association Members and have a number of branches across the United Kingdom, meaning we have qualified and experienced surveyors and technicians local to you.

Dry rot means the presence of a wood-destroying fungus, known by its scientific name Serpula lacrymans. It is a type of brown rot that feeds off the cellulose and hemicellulose found in timber to cause cuboidal cracking, which makes the wood brittle and weak, meaning that over time it can damage the structural integrity of the property and leave wooden timber beams and joists structurally unsafe.

Dry rot differs from other types of wood rot because it will spread over and through other damp materials or masonry to the rest of the house far beyond the initial infestation site, whereas wet rot will remain localised to the source of moisture.

Once dry rot spores germinate through an initial source of moisture, it is then able to spread across surfaces in search of further timber to attack. It is often found in damp, dark and poorly ventilated areas, making it particularly common in sub floor voids, attacking joists and floorboards. In these areas, it will often look like cotton wool, with occasional sulphur yellow 'flashes'.

It is one of the most serious problems properties in the United Kingdom face, so identifying the tell tale signs of dry rot is essential to prevent further damage.

It can be difficult to differentiate between dry rot and wet rot due to the fact that both types of rot share a number of tell-tale signs. Both these forms of rot cause wood to crack, leave affected areas soft and spongy and can lead to fungus-like growth on timber.

One of the main differences between dry rot and wet rot is that wet rot requires an ideal moisture content of around 50%-60% whilst dry rot will grow with a moisture content of around 30%-40%. Because of this, wet rot will only be present near a prevalent moisture source and as such is often found in the vicinity of leaking appliances, burst pipes, roof leaks or damaged window sills. In contrast, dry rot can spread over relatively dry timber if the humidity is right.

The treatment process involved with dry rot and wet rot will differ, making it extremely important for the correct diagnosis by a trained and qualified surveyor.

Dry rot is able to spread through masonry and brickwork and can even grow over plasterwork, steelwork and carpeting.

Dry Rot grows using structures called hyphae which join together to form a mass known as Mycelium. This is similar to a root system, spreading out to gather nutrients. The mycelium is able to carry nutrients through masonry, back to the main fungal mass and structures called strands can transport moisture to the growing front. During the treatment process it is important to deal with any dry rot mycelium and strands within masonry, otherwise the problem could reamerge in the future if a source of moisture is present. This is why it is so important to carry out a thorough investigation to identify the full extent of the dry rot outbreak.

Because of its ability to spread across different surfaces, dry rot causes serious damage to many buildings, especially older and historic properties with extensive decorative and structural timber.

Dry rot is one of the most serious property problems there is, so identifying the signs early is the best way to prevent further damage occurring. It can be difficult to identify as it is often in hard to reach places, but there are often telltale signs that a problem is caused by dry rot.

If you suspect a fungal decay problem, you should book a damp and timber survey so a qualified surveyor can fully assess the extent of the damage, and provide guidance on how to prevent the problem from recurring.

Even if you are unsure if the problem is caused by dry rot, the best cause of action is for a qualified surveyor to investigate, as this will give you peace of mind a professional has inspected the area, and provided you with a definitive answer on the problem.

Common signs of dry rot to look out for:

Dry rot has a distinct lifecycle which requires a source of moisture and wood to feed off. In the right conditions dry rot can spread quickly and cause severe damage to wooden structures. These can be identified by a trained eye, as indicating a dry rot outbreak.

Dry rot spores are always present in the atmosphere all around us and are harmless unless the right conditions are present. To develop into an infestation, there must be a source of moisture present, and a lack of ventilation is beneficial. Dry rot is often caused by building defects allowing moisture to penetrate into the fabric of a building, causing timber to become moist.

Dry rot spores will land on timber with a moisture content over 20% and will then begin to germinate and produce hyphae (fine strands of fungal growth) that are greyish in colour. This will develop into mycelial growth.

Once the hyphae strands are formed, they join together to create a mass called mycelium which then grows into and across damp wood and masonry. It can also grow over materials such as plaster, mortar and brick as it searches for more cellulose-containing timber to feed on.

When the growth is advanced, a fruiting body (sporophore) may develop. This fruiting body takes the form of a “fleshy pancake”, the surface of which is orange/ochre-coloured. It is at this stage in the dry rot life cycle that Sporophores or fruiting bodies will begin shedding millions of spores in the form of red dust, so the process repeats itself and the infestation becomes more entrenched in the home.

Although individually these spores are almost invisible to the naked eye, in houses with dry rot problems you will often find that when they group together they appear as a tell-tale fine orange or brown dust.

If left over time, dry rot can lead to significant structural damage across a full property. It can spread throughout multiple rooms and even on different stories, using damp underfloor areas and wall voids to remain hidden from view, until a sporophore appears. It is possible for dry rot to spread through party walls into other properties in search of timber to attack.

Because it can spread so quickly through a property it is important to have a survey carried out by a trained and qualified surveyor who is experienced in identifying the full extent of a dry rot outbreak.

Dry rot can be a complex problem so the surveyor will take their time to fully investigate, and provide recommendations to make sure the problem is solved for good. Rentokil Property Care dry rot treatments typically come with a 30 year guarantee, giving you complete peace of mind the problem will not return.

Dry rot is notoriously difficult to fully eradicate and that is why you must ensure the specialists you instruct to solve the problem offer real and meaningful long term guarantees.

During the treatment process it is important to make sure that all affected timber is removed, and any spores or mycelium existing on masonry are dealt with. The source of moisture fueling the problem must also be addressed. Only then will the property be free of a dry rot problem.

Our long and proud trading history alongside the experience and professionalism of our surveyors and technicians makes us a reliable company to use for dry rot control. From our industry leading treatments and our long term guarantees, Rentokil Property Care are here to help from start to finish.

If you are worried about a timber problem in your property and you think it could be dry rot, Rentokil Property Care are here to help. We can provide you with clear answers and long term solutions to give you peace of mind that your property is protected.

The first step is to get a damp and timber survey carried out by a qualified surveyor.

A damp and timber survey is used to identify damp issues and timber defects, as more often than not a damp problem is the source of moisture required for a dry rot outbreak.

It is best to use a PCA accredited surveyor with a CSRT (Certificated Surveyor in Remedial Treatment) or CSTDB (Certificated Surveyor of Timber and Dampness in Buildings) qualification. They will investigate the dry rot outbreak, the source of moisture causing the problem, and then assess the extent of damaged timber.

They are experts in investigating what can often be a complex problem, and will survey your property to strict industry standards. All findings will be detailed in an easy to read survey report, and the surveyor will be able to answer any questions you may have on the processes involved.

Rentokil Property Care are experienced in carrying out damp and timber surveys on all types of buildings, so no matter the size or complexity, whether it is a domestic or commercial property, we are here to help.

Once a Rentokil Property Care qualified surveyor has confirmed a dry rot outbreak, and you wish to go ahead with dry rot treatments, remedial repairs carried out by our experienced technicians will begin.

For dry rot remedial repairs, we aim to:

• Remove the moisture source causing the problem, whether it is caused by a building defect, a lack of ventilation, rising damp or penetrating damp.
• All affected timber is removed beyond visible signs of damage.
• An application of fungicidal treatments to kill dry rot spores.
• Where the dry rot has penetrated through masonry, this will be treated with fungicide.
• Replace any damaged timbers
• Where applicable, provide you with a long term guarantee, to protect your property.

From the first day on site, our technicians will talk you through the full process, and are equipped with protective floor coverings, Hilti dust extraction units and vacuums in order to keep your property clean and tidy.

If you think you have a dry rot problem in your property, you want to trust the company you are working with will get it right the first time. Rentokil Property Care has been working in peoples homes and businesses for over 70 years, correctly identifying property issues and providing long term solutions.