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How To Identify And Treat Dry Rot

Rot is one of the most dreaded causes of home damage, especially because it can affect the structural integrity if left untreated. Many homeowners are familiar with wet rot, but dry rot is just as damaging as the wet varieties.

It is important to identify it as soon as possible to prevent costly damage and repairs. Whether you are currently suffering from a dry rot infestation or want to take preventative steps to protect your home, it is important to understand what it is, what it does, and how to identify and treat it.

What Is Dry Rot?

Dry rot is a term used to describe a specific type of wood decay caused by the fungi, Serpula lacrymans. This fungus normally feeds off timber but has been known to affect wood in both ships and buildings. Brown decay is another name for it, but dry rot is more commonly used.

It is called this because of the way the fungus feeds off the cellulose in timber in order to grow and spread. The process leaves the timber or lumber dry and brittle, often with noticeable cracks running through it.

Dry rot is different from the wet varieties of decay, because although both need a source of moisture to begin germinating, the “dry” version of the fungus is capable of spreading far beyond this initial water source. In search of more timber or lumber to consume, the spores are capable of spreading through thick walls and over surfaces to attack another source.

This type often leads to the appearance of a mushroom-like body called a sporophore, which give off millions of spores in the form of red dust, spreading the infestation further.

Dry Rot Lumber

What Causes Dry Rot?

Dry rot occurs when wood is exposed to excess moisture and grows damp, like in situations with water damage. In combination with excess air, the damp lumber becomes a breeding ground for bacteria and micro-fungi which begin to break down the wood’s cell structure. This creates even more room for moisture. Once the moisture level exceeds anywhere from 20-30%, the wood is susceptible to the fungus.

Like most fungi, it spreads through airborne spores. Individually, these spores are invisible to the human eye. They are also everywhere, meaning your home is already exposed to them, even if the lumber is not infected. If there are large amounts of them, they may appear as orange or brown dust in a space.

Once the spores land on wood in a favorable environment, they take root. These roots are called hyphae and act as the root of the decay, stringing fine strands to grow through the lumber. The hyphae feed on the sugars, or cellulose, within the wood, which leads to cracking and weakened beams. Hyphae then grow and merge to create a white, fluffy-looking growth known as mycelium.

As mycelium, the infestation can travel great distances to find new sources of food, spreading through various building materials, including brick, mortar, and steel. This allows the fungus to continue feeding on the wood throughout the entire house. If the structure dries out or conditions for growth become unfavorable, the mycelium can lay dormant for long periods of time and have the ability to come back to “life” once the environment is favorable again.

Mycelium growth also becomes weakened by exposure to sunlight or the absence of excess moisture, air, or consumable lumber. At this stage, the fungus begins to produce spore caps, known as sporophores, which release more spores into the air. Once these spores find a favorable environment, the cycle begins again.

Identifying Dry Rot

Due to the fungi’s ability to spread throughout structural materials, it is important to identify whether your property is suffering from dry rot or another kind of fungal infestation. Early identification can also minimize the amount of damage done to the overall structure of your home. Fortunately, there are several characteristics that make the fungus easily identifiable.

Musty, Damp Odor

Perhaps the most obvious sign is a musty, damp, and unpleasant odor throughout the house. The odor is also one of the earliest signs, so it might be worthwhile to investigate the rest of your home for other signs of the fungus, like the following.

Damaged Timber

Damaged or infected lumber is another obvious sign. Any lumber affected will often darken in color and become so dry and brittle that it easily breaks or crumbles. Look for shrinkage and cracks in a ‘cuboidal’ manner.

Concentrated Spore Dust

Dry rot spores are very common and usually harmless, but if they begin to appear in concentrated patches of rust-colored dust, this is a sign of an active infestation. The fruiting body, or sporophore, of the fungus releases large amounts of spores in an effort to spread further and find new sources of food.

Visible Fungal Growth

If the infestation has progressed to later stages, you may notice visible fungal growth. The first stage of this growth, as mentioned previously, is the hyphae, which resemble a whitish, cotton-like substance growing on the lumber. Sometimes, the growth leaves behind a texture resembling snakeskin and can also form teardrops.

As the fungus progresses, it becomes mycelium, which is brittle and typically cracks when you bend it. In its final stage, the sporophore, it looks like a soft, fleshy pancake, with an orange or rust color. This is normally where you would find a large concentration of rust-colored spores around the infected beams or planks.

In less humid conditions, the fungus may develop a skin that ranges from a silky grey to mushroom white color. It is often tinged with patches of yellow or lilac. This skin can be easily peeled away in the same way the skin of edible mushrooms is easily removed.

Handyman Wood Beams

Dry Rot Treatment

This fungus affects timber or lumber that is damp and has excess moisture content. Removing the source of the moisture should be the first step you take to treat the problem. This process could include repairing a damaged roof or wall, replacing leaky pipes, or other damp-proofing measures.

You should leave the wood to dry afterwards, and you may need to add additional ventilation to help reduce humidity. After these basic steps, you can then use other treatment methods.


Borate-based preservatives are often used as a timber treatment but can also be used to destroy the fungus in existing lumber. This involves drilling holes into the affected areas, injecting borate solution, or spraying the solution over the infected beams and planks.

A disadvantage to using borates is that they are water-soluble. Though this helps them penetrate wood more deeply, it also means the protective coating will wash away over time if the moisture problem is not taken care of first. This is why it is important to check for any signs of water damage and make the necessary repairs or replacements.


Another popular chemical treatment is glycol, which is a chemical component in antifreeze and other de-icing solutions. Ethylene glycol may cause serious health problems with too much exposure, but propylene glycol is made using less-toxic chemicals and may be a better alternative.

Glycol treatments might become diluted or wash away in a moist environment, but it can be sprayed on painted or coated wood surfaces, absorbing into the material without damaging the surface. Exceptions to this are epoxy and polyurethane, which are more resistant treatments.


Some people opt to completely remove and replace wood that shows signs of dry rot. This is an expensive but highly effective method, though newer methods of containing the fungus have made this option less popular. After removing the infected lumber, be sure to treat nearby wood and surrounding areas with a fungicide.

In certain cases, replacement is inevitable. It is not recommended you try to repair any lumber in areas that provide structural stability to your home, such as beams and joints. In those cases, it is much safer to replace the beam than repair it.

It can be difficult to treat an infestation on your own. Without the right tools, you could think you have gotten rid of it, only to have the fungus come back and cause even more structural damage. Fungicide and other treatments are also toxic and can be harmful to your health if you are not careful. Hire a qualified and experienced team to take care of your problem for you.

Repairing Dry Rot Damage

After any cases of dry rot have been treated, you need to address the damage left behind as a result. If you are confident the wood is repairable and that you are able to do the job, be sure you have the right tools before you begin.

Start by removing as much of the damaged and infected wood as possible with a wood chisel and wire brush. Be as thorough as possible. A flashlight can help you illuminate the area you’re working in and help you find infected lumber.

If you cannot reach all the dry rot, inject an epoxy consolidant into the lumber through drilled holes in the material. This will reinforce the affected fibers and bond with unaffected surrounding areas, strengthening the material. You can find epoxy in most home improvement stores.

Once the epoxy has cured, a wood-patching product completes the repair. Typically, you apply the putty-like material to the crumbling material and let it cure. Once it has completely cured, it can be shaped to fit the space with a chisel and sandpaper.

Keep in mind that when doing your own repairs, you run the risk of missing some of the dry rot or not getting rid of all the affected lumber. The fungus can then spread deeper into the structure of your home. If you are not an experienced DIY-er, consider enlisting the help of your local, professional handyman.

Dry Rot Wood Treatment

How Can I Prevent Future Problems?

When it comes to any kind of wood rot, the key to avoiding problems is to prevent them. It is much easier and cheaper to prevent an infestation than it is to fix it. Below are some suggestions on how to effectively prevent dry rot.

Seal any and all cracks around exterior doors and windows with caulk to prevent moisture from seeping in, especially when it rains. If there is already caulk in place, scrape away the old, hardened caulk, which is likely not doing its job, and replace it with fresh caulk. This adds an extra layer of damp proofing to your home.

If you are able, consider cleaning your home’s gutters regularly. This should be at least twice a year, if not more. Cleaning them will prevent any blockages that can lead to water running over the backside of the gutter and down the side of your home, causing further water damage.

Most modern bathrooms have these, but if your bathroom does not, install exhaust fans to remove steamy air and excess moisture caused by showers and tubs. Not only can this moisture lead to fungal growth, but it can also cause other problems as well, such as mold and other growths.

If your home still has a problem with moisture, especially if you live in an area with wetter weather, consider using a dehumidifier to help drain the air of any excess moisture.

Hire A Professional Today

When it comes to dry rot, there are too many factors to consider. You might not remove all of it, or effectively remove the source of the moisture, leading to further damage to your property. The treatments used on the fungus can also be harmful if applied incorrectly or simply through exposure. This doesn’t even go into the amount of time and money it could take to repair and replace any damaged wood.

The experienced and professional team at Kaminskiy Care and Repair can handle your dry rot problem. You can trust that they’ll do the job effectively and efficiently, ensuring your house is safe and rot-free. We understand most homeowners would rather be enjoying their home than spending their time fixing it up. That’s why we offer affordable maintenance and renovation for your property. Call us today for an appointment and let us take care of the infestation for you!