Guide To Wet And Dry Rot

Dry and wet rot in timber can become a major problem. As a building material, timber is used in nearly all aspects of construction work. This can include everything from floorboards and skirting to the framework of a house. Rot is often caused by exposure to moisture, something which timber regularly comes into contact with it.

Rooms that may be particularly susceptible to rot are bathrooms and kitchens. Conservatories and roofs are also very likely to be affected.

Luckily, homeowners can use wood treatments to prevent the damage caused by rot. However, these are not guaranteed to work at all times. As a result, it is a great idea to learn more about the causes of rot. You can then address how a potentially expensive case can be avoided.

Our guide on dry and wet rot covers what each condition is and how you can manage it.

About Dry Rot

Dry rot is highly destructive to woodwork. Also known as Serpula Lacrymans, this fungus can reduce joists, stalwart beams, and timbers into hazardous and crumbling structures. Regardless of its name, it needs wood with a moisture content of at least 20% to thrive. Dry rot loves warm, damp, and unventilated conditions, which is why it is commonly found in locations that cannot be easily seen.  These include roof trusses, underneath the stairs and wooden floors, and behind skirting boards.

Some of the tell-tale signs to look for include:

• Concentrated Spore Dust
• Damaged Timber
• White Mycelium
• Grey Strands on Timber
• Musty Smell
• Fruiting Bodies

Dry rot spores can travel quickly, and they are always on the lookout for more timber to feed on.  It is not only timber that they affect but plaster and masonry as well. Within a matter of months, the whole structural integrity of a building may become compromised.  As a result, it is important that you act fast if dry rot is suspected.

What is Wet Rot?

Wet rot is fungi which breaks down wood and causes it to decay. As part of the natural ecosystem, the fungi recycle dead wood and release nutrients into the environment in the process. It is more likely to occur than dry rot, but the damage is not as serious when compared. Decay happens on wet timber and other areas which continuously remain damp.

Even though it is often confined to wood, decay may also happen on wallpaper, damp plastic, and carpets. Some of the key signs to look out for include:

• Shrinking or Crumbling Timber
• Flaky or Damaged Paint
• Fungus Growing on Timber
• Spongy or Soft Wood
• Bleached Wood
• A Damp or Musty Smell

Why Wood Rot Happens

Rot typically occurs if timber remains damp for a long period of time.  Softwood rot will start developing, causing the timber to soften. If the timber has moisture in moderate levels but the air can also freely access, a dry rot may develop.  When this occurs, a bigger problem can be created.

The fungus maintains growth using humidity in conditions that are poorly ventilated. Once decay has started to spread, it will begin to cause problems. This includes attacking the structural integrity of the building. If the dry rot has not been identified immediately, it is important that you get rid of and replace all the affected timber. When the structural materials start to absorb damp from either a leaky roof or pipe, wet rot will start developing. In order to get this problem solved, you will have to stop the cause of the damp.

You should isolate the timber from the damp source before you treat any affected areas. When treating the area, it is important to also treat the unaffected areas. This helps to prevent any future decay outbreaks.

The appearance of wet rot can darken the timber and develop an appearance of a characteristic crack. Consequently, the wood will eventually lose its strength and in several cases may become unsafe.

Dry rot is much more dangerous as it digests the parts of the timber that give it stiffness and strength. Furthermore, it may spread without any source of moisture.

Treatments for Wet and Dry Rot

There are several different approaches to treating both types of rot. A professional team such as ours here at Aquafoss can help you to determine the best approach for you. The most common treatments used include:

• Primary Measures
• Secondary Measures
• Fungicidal Paints and Renderings
• Physical Containment
• Masonry Sterilisation
• Fluid Injection
• Conventional Fungicidal Pastes
• Borate Rods

Below are some brief explanations of each of these approaches.

Primary Measures for Control and Treatment

The most vulnerable feature of fungi is that it usually requires water.  It is for this reason that treatment requires the complete elimination of damp. This forms the primary measure of removing both dry and wet rot.

It is important to find and rectify the fungi’s source of water which is causing and maintaining the rot. Another important thing to do is to promote and maintain immediate drying conditions.

Removing the source of water for fungi is the first point of attack. Therefore, it is important that you stop further ingress of water. This action alone will help to treat and eliminate the activity. This action is required to promote and maintain a good drying condition, eradicating the organism.

Secondary and Supporting Measures

After doing the primary measures for treatment and control, you need to remove the infected wood. Removing the food source is a big step towards stopping growth and further spread. This may mean removing a large amount of timber, depending on the specific case. However, it is important to note that in cases where rot occurs in a historic setting, a much less destructive approach should be taken. Drying techniques are used, which are monitored carefully at all times.

Once isolated, you may be able to reinstate the timbers using joinery wrap and joist hangers. These will deny the fungi a possible source of food and prevent timbers from becoming wet.

Furthermore, you may reinstate a pre-treated timber, pressure impregnated, or double vacuum as needed. Inert materials like steel, concrete, and more can also be used. You should consider the use of preservatives for steeping joist ends before reinstating.

Some other treatments include:

• Fungicidal Paints and Rendering – Function by forming effective chemical barriers in accordance with the use of zinc oxychloride.
• Physical Containment – Joinery lining around the adjacent timbers.

Masonry Sterilisation

This is the application of a special water-based fungicide to the masonry. Usually conducted through a surface spray that has a masonry biocide, sterilisation is often all you need. However, with a more severe case, a toxic box or cordon sanitaire may be used. This involves a drilling perimeter in the rotted area and the masonry is injected under pressure. The work will be done with a spray for liberal surfaces or a brushing treatment with the sterilant.

Traditional irrigation is on the complete wall and is done using standard water-based fungicides. These are then injected under pressure. The process may introduce too many problems and it is not necessary.

It will also introduce excess water to the masonry and cause more damage than dry or wet rot. Full saturation may not be attained, and it is also not a necessary use of biocide chemical treatment for timber.

Fluid Injection

This involves injecting fungicides carried in organic solvents through special plastic valves driven into the wood. The fluid needs to be injected under pressure. This may give a good distribution of the fungicide but ensures that the wood is not too wet.

Unlike the conventional paste preservatives, fluid is being injected within the wood.  It does not depend on surface penetration. However, it is very likely that timbers are wet or damp.  When this treatment is applied, it may only result in poor distribution of preservative. This is because there is a presence of a resident moisture.

Conventional Fungicidal Pastes

Typically conventional pastes consist of a water and oil emulsion, with a high oil content carrying the fungicide.  You tend to get deep penetration as long as you apply a sufficient amount, with the wood not being totally wet. However, there are many cases where the wood has been damp, leaving them at risk of decay. In these cases, the conventional paste preservatives will not be likely to penetrate to any great extent. This is due to the resident moisture in the wood.

Additionally, any applied paste to the surface will rely on diffusion in order to reach deep within the wood. Through these pastes, the necessary fungicide level for rot prevention is not likely to be attained. This is because the paste will stay nearer the surface.

Borate Rods

This preservative is supplied as rods that look like a glass. Consisting of a special fusion of boron compounds, it is inserted into holes and drilled into the wood. The rods are soluble in water and need to become damp. This is so that the rod will slowly dissolve and distribute the preservative by diffusion toward the areas that are wet.

Once the rod has been embedded in the wood, the preservative is distributing accurately into those areas. This acts as a risk to the decay. They have ideal use in those areas which are risky to decay but still not affected. This includes window joinery, embedded joist ends, and more.

Other Treatments

It is important to control and treat the spread of both forms of rot. These treatments should be considered when preventing the survival and growth of dry and wet rot. Prevention is used alongside the practices and methods for its treatment and control. The emphasis is to attack the important requirements for survival and growth.

On places where chemical treatment is being used for supporting the primary treatment, the wood should be assessed.  To lessen the decay risk to damp timbers, it is important entire parts of wood at risk are treated.

Boron can be effective when compared to the conventional pastes. The boron-based materials are particularly designed to work in high-risk cases, including when the timbers are at risk to decay and are damp. The glycol and boron formulations have the additional benefit of distributing quicker than that of the solid borate rods. Therefore, they create a greater possible protection and lessen the risk of rotting.

It is often used where the contents of moisture for dry and wet rot serve as the process for survival. The solid borate rods do not distribute as effectively under these marginal conditions.

Undertaking Repairs to Timber

The treatment for dry and wet rot needs to be the responsibility of specialist treatment providers and companies. This includes all the attendant building works and any chemical treatment whenever important. A specialist company will fundamentally understand all of the involved elements. They can thoroughly assess the outbreak of wet and dry rot. These act together with the importance of the treatment measures and risks associated.

Aside from that, the use of a damp specialist will help you to remove the problem of spread responsibility. When several treatments are applied by different persons, there is no consistency in the work completed. A specialist can manage the full situation, third-party treatments may not work together cohesively.

Contact Aquafoss Today

For more details about wet and dry rot, give us a call now on 01525 374406.