What is Wood Rot and How to Treat it

Generally, prevention is the best way to deal with wood rot. Experts recommend sealing all the cracks in areas subject to high humidity and using a dehumidifier to eliminate the excess moisture.

But what happens when you have to deal with wood rot? Do you have to replace the entire structure?

Fortunately, you do not always have to tear out and replace the lumber.

Even better, treating and controlling lumber rot with small bleach amounts is possible.

So, let’s engage in the topic: What is Wood Rot and How to Treat it?

Bleach stops wood rot, whether dry rot or wet rot. Further, it works best on lumber unexposed to elements, like under a roof or indoors.

Bleach also kills and discourages mold and mildew growth. Therefore, most woodworkers use it on pressure-treated lumber.

In addition, wood preservatives eventually become weak, creating a conducive atmosphere for wood rot.

So, you may deal with a recurrence, and bleach is an effective option.

Please note that bleach cannot stop wood rot after it enters the lumber. 

Moreover, wood rot is more than a nuisance to your home’s beauty. It also causes devastating structural damage if it persists.

Therefore, it is prudent to prevent wood rot as much as possible. Also, read this article for more information on the wood condition and ways to remedy the problem.

What Is Wood Rot?

Image of a rotting wood . But, Does Pressure Treated Wood Rot?
A Rotting Wood

Wood rot is decay triggered by fungi and moisture. The lumber must be consistently damp for the microscopic organisms to ‘set up shop.’

Typically, fungi do not grow on dry wood. Yet, more than five million fungi exist in our soil and air.

Hence, there is no escape.

Further, although some fungi types, like mushrooms and yeast, are beneficial, others are destructive.

Lumber is a series of straws joined together. Thus, cutting or opening the material is like opening a box of straws.

Also, wood naturally absorbs water, which permeates throughout the structure.

As a result, the wood rots, and the rot grows like an infection, compromising the lumber’s integrity. You cannot ignore this issue, as countless homes and condos are wood-made. 

In addition, wood rot causes decay at varying levels, ultimately resulting in structural and cosmetic damage.

Types of Wood Rot

We have two primary wood rot types; wet rot and dry rot. Wet rot needs a higher moisture content, mostly levels above 50 percent.

On the other hand, dry rot grows at a lower wood moisture content, usually 20 5o 30 percent.

Below is more insight into the wood rot types.

  • Wet Rot

Wet Rot is a wood-eating fungus type in buildings with unprotected timber components. 

Further, we have multiple fungus variations, but Coniophora Puteana is the most common type.

This rot type sustains itself by feeding on nutrients and moisture from the wood. But it can cause decay in carpets, wallpaper, and plaster.

Wet rot spreads by feeding on lumber, then emitting spores into the air. These spores land on fresh wet wood and feed on it.

As its name suggests, wet wood rot mainly occurs in areas with excess moisture levels.

Also, it is an all-encompassing term for various fungi types flourishing in high-moisture regions.

Common areas susceptible to wet wood rot include leaky pipes, damaged gutters, and poorly fitted roof tiles. Wet rot also grows under floors, windows, frames, doors, and steps.

But it is challenging to identify wet rot as it thrives in dark and poorly ventilated areas like roofs, lofts, and cellars. 

Nevertheless, below are some wet rot characteristics to help with your assessment.

  • The lumber features dark brown stains.
  • It is moist to the touch.
  • You will notice a wet odor and a musty smell.
  • The wood grain splits or has longitudinal cracks.
  • The surface quickly caves in when poked with a screwdriver.
  • You’ll observe damaged or flaking paint.
  • The lumber shrinks.
  • The surface has mycelium strands.
  • The fungus easily cracks and crumbles if it dries out.

Please address wet rot as soon as you notice the above signs. Otherwise, the situation will worsen, posing a risk to the structure’s integrity.

In addition, we have various wet rot types. They are

  • Brown Rot

Brown rot fungi break down cellulose using hydrogen peroxide from broken-down hemicellulose. These tiny molecules slip into the lumber and spread fast.

Further, the wood shrinks and adopts a nasty brown hue. Then, it ultimately cracks into separate cubes, primarily weak and crumbly.

Brown rot has a darker appearance than white rot. And it closely matches the affected wood’s color.

Sometimes, this rot type cannot digest the lignin in certain lumber species. Instead, it feeds on cellulose and sugar, making the affected area brown.

  • Soft Rot

These fungi cause soft rot by secreting cellulase, which destroys the wood’s cellulose.

As a result, they generate tiny wood holes, causing cracking and discoloration.

Soft rot fungi thrive in hot, wet, and cold areas. Moreover, they cause damage to the lumber’s bark despite its high tannin levels.

Remember that wood tannins make it notoriously difficult to decompose. Yet, this fungi type manages to destroy the lumber.

In addition, common soft rot fungi variants include Ceratocystis and Chaetomium. But they are not the worst offenders.

The top chart mayhem position belongs to white rot fungi, the most successful and aggressive decomposer.

  • White Rot

When wet rot fungus preys on certain wood species, the resulting decay is white. Thus, white wood rot.

This wood rot type occurs when the fungi digest lignin and cellulose in the wood. As a result, it strips the lumber’s darker colors.

In addition, the material has a moist, soft, sponge-like, and stingy state with a soft yellowy or white color.

White rot involves multiple enzymes, enabling it to oxidize lignin. Lignin is a polymer bonding the wood’s cells and enhances natural rigidity.

For instance, the honey mushroom attacks live trees, causing untold damage.

Other white rot fungi variations include the artist’s conch and turkey tail. They are fascinating and oddly lovely.

Also, some are edible, like the famous Shiitake mushroom, prized globally for its flavor.

  • Dry Rot

Dry rot is a single fungus type. Further, it is referred to as Serpula Lacrymans and generally settles on timber and woodwork.

This rot type spreads quickly. And since it does not need as much moisture, the situation may be hard to contain.

Some distinguishing attributes of the wood rot type include

  • The affected wood loses structural strength.
  • Dry rot damages surrounding timber structures.
  • It causes visible fissures along and across the wood grain.
  • You’ll also notice mycelium growth.
  • The fungus resembles white cotton wool and fades to a grey hue later.
  • The organisms produce crimson spore dust.

Wet rot is less destructive than dry rot. It remains confined to wet areas, unlike the latter, which can grow anywhere.

Nevertheless, it is prudent to treat all wood rot despite its variations. Otherwise, you risk compromising a building’s structural integrity.

What Causes Wood Rot?

Practically, fungi are the only wood rot agents. Besides, although most wood decay occurs due to basidiomycetes, some ascomycetes cause wood deterioration.

We also have other deterioration agents like marine animals, insects, and ultraviolet light, but they do not cause decay.

In addition, their damage is not quantitatively equal to decay.

Fungi are the simplest version of plant life. These microscopic spores float in the air and easily land all over homes.

However, five primary conditions must be present to encourage fungi growth.

Interestingly, even if you correct these conditions, fungi are still present. In addition, they will resume growth when conditions become favorable.

The below conditions must occur at the same time for rot to occur. They include

  • Source of Infection

Fungi are the only wood decay agents as sources of deterioration. They spread in a few ways.

For example, decayed lumber may spread the infection to healthy, sound wood parts through normal fungi growth.

It may also spread directly from the soil or ground to the lumber. 

The soil’s organic matter is home to growing fungal organisms, affecting the material upon contact.

Lastly, sometimes airborne fungus is the culprit. It spreads through the air to solid, healthy wood.

  • Suitable Substrate

Fungi require an excellent substrate to grow and spread. In this case, the wood tissue provides the needed food.

The wood cell’s lignin, cellulose, and other components fuel fungi growth.

However, not all wood types rot because of fungi. We have exceptions, like Redwood, Cedar wood, and White Oak, which are rot-resistant.

These species last longer and have toxic substances to fungi. In addition, you can eliminate fungi’s food supply using wood treatments. Water and oil-borne chemicals are perfect for this job.

  • Moisture Content

Dry wood does not decay, period! Moisture content is critical when determining wood rot causes because all wood-decaying fungi need ‘free water to grow.

Free water is the moisture amount above the fiber saturation point.

It occurs when water soaks into the lumber until you only have moisture bound in the fiber cell walls.

Air-dried lumber has 18% water, below the fiber saturation level. Therefore, it is not ideal for fungal growth.

Besides, wood is considered immune to fungi and rot when the moisture content is below 20 percent.

  • Oxygen

Oxygen is an unsurprising component as most living organisms require it to survive. 

Therefore, wood wholly soaked in water does not have air for the fungi. So, it will not rot.

Further, the fungus will suffocate by carbon dioxide as there is no air interchange.

  • Temperature

The ideal temperature for fungi growth ranges from 65 to 95 degrees Fahrenheit. However, we have slight variances depending on the lumber species.

Fungi growth rate slows down when the temperature is much lower or higher than this range.

Also, at freezing temperatures or above 100 degrees, the organisms will make very little progress or cease.

Finally, wood is bound to rot when the above components are present. Some of these ingredients are often present in the lumber or its surroundings.

However, the wood immediately starts to rot once water enters the equation.

How to Stop Wood Rot Using Bleach

Bleach is a potent chemical against wood-destroying fungi and stops them from recurring.

Furthermore, chlorine bleach removes rot stains from the lumber and brightens its natural hue.

Below is a straightforward guideline on using the formula. But first, you need a few supplies to deliver a satisfactory finish.

The primary materials are bleach, a stiff brush, a cotton ball or spray bottle, a putty knife, a wood filler, and sandpaper.

In addition, get gloves, a nose mask, and goggles as protective clothing and follow the simple steps below.

  • Establish the Moisture Source

Determine the source of the moisture penetrating the wood and fix it.

Look out for leaking windows, pipes, and washing machine leaks, penetrating or raising damp levels.

Then, estimate the rot damage degree.

Also, prevent future rot by fixing the source of moisture, repairing the leaks, and using a dehumidifier to dry the excess lumber moisture.

  • Prepare the Lumber for Bleach Treatment

The house parts most vulnerable to lumber-destroying fungus include windows, the door frame area, decking, and roofs.

Check if the rot spreads over several boards and if the damage is beyond remedy. If yes, replace them with pre-treated ones.

Conversely, if the wood rot damage is repairable, scrape the rotted wood pieces on the corners and crevices using a putty knife or a chisel.

Then, brush the lumber using a stiff brush to remove all the rot fungi.

  • Apply Bleach to the Affected Area

Bleach can irritate your eyes, skin, and nasal cavity. Hence, please use it in a well-ventilated place.

In addition, wear protective gear such as safety goggles, gloves, and a respirator mask during operation.

Dilute the formula with water in a plastic jar. Then, soak a cotton rag into the mixture and rub it on the rotted lumber.

Also, apply the bleach to the wood parts surrounding the rotted area.

Give the formula sufficient time to penetrate the wood. Rinse off the excess with warm water and let the material air dry.

Alternatively, you can transfer the diluted formula into a spray bottle and spray it on the wood.

This strategy works best for demanding projects as it covers a large area.

  • Apply Wood Filler to Crevices and Add a Topcoat

Fill the crevices resulting from extracting rotting lumber. But ensure that the lumber is dry before proceeding.

You can use multiple wood fillers, whether epoxy or polyester wood filler.

Also, sand the product after drying to match it with unaffected lumber areas. Afterward, prime and apply a finish of choice.

  • Maintain the Wood in Good Condition

Keep the lumber in good condition for enhanced longevity.

Ensure there are no moisture leaks in the house. In addition, keep the structure dry using a dehumidifier when living in highly humid environments.

How Long Does It Take for Wood Rot to Develop?

Typically, wood rot needs about seven to ten days to develop. In addition, various lab experiments confirm that after this duration, dry rot spores start germinating.

However, the wood may take one to six months for rot to develop if it is in a 2×4.

But regardless of the duration, take appropriate preventive measures to keep rot away from your wooden structures.

Conversely, it is challenging to establish a consistent growth time frame for wet rot.

Further, this rot type only spreads in damp areas. Thus, you can mitigate its risk by removing moisture.

Although the speed and spread of rot vary widely, all cases require suitable activation conditions.

These conditions include proper temperature, say between 65 to 90 degrees Fahrenheit, food (the wood), oxygen, and moisture.

Also, the wood begins to rot in one to six months if

  • You leave it untreated.
  • It sits in water, hot, and humid spaces.
  • The area is near or at the ground.

On the other hand, it starts to rot in one to three years if

  • You leave the surface untreated.
  • The area is in a hot climate.
  • You do not use the correct paint on the wood.
  • The lumber collects moisture frequently, say from sprinklers or rainfall.
  • You leave the wood uncleaned, especially when handling siding and structural posts on fencing, fascia, soffit, or patio.

Unfortunately, wood does not last forever. It eventually rots despite painting, annual cleaning, and using treated solutions.

Finally, call a siding or roofing company as soon as possible when you notice water leaks into structural wood.

How to Restore Rotting Wood

Ultimately, lumber rots due to prolonged moisture exposure. 

This scenario leads to concerns as it is unsightly and causes home damage when left untreated.

Thankfully, wood rot is easy to remove. You can have your home structures looking as good as new.

Check out the wood restoration strategies below.

Strategy One: Patch the Rotted Wood with Epoxy

  • Paint the Surface

First, paint the lumber with a bonding compound. Also, use a broad brush to apply thin, uniform coats.

Coat the affected area and ensure complete coverage. This way, you guarantee better epoxy adhesion.

  • Mix the Epoxy

Blend a two-part epoxy using a putty knife. In addition, dispense enough to cover the entire rotted area.

Mix both epoxy parts thoroughly till you get a uniform hue.

Next, use a flat glass or plastic piece as a mixing palette. The epoxy will not stick to these surfaces, guaranteeing a successful operation.

Most epoxy products have a one-to-one mixing ratio. But follow the manufacturer’s instructions.

Use a gun applicator to apply the formula in pre-measured ratios. 

Also, work within 30 minutes of mixing the epoxy. Otherwise, it will dry out and compromise your work.

  • Shape the Epoxy on the Surface.

Use a putty knife to shape the paste on the lumber. And apply a generous product amount and push it into the rotted region.

Press the epoxy with the putty knife’s edges to compact it. You can use a scrap wood piece as a straightedge to deliver a clean, flat edge.

  • Remove the Excess Epoxy

Get a clean putty knife and scrape off the excess formula. 

Further, use the knife’s edge and corners carefully to match the epoxy to the wood’s edges. This way, you guarantee a clear and even look.

You can also utilize a plastic putty knife to smooth the epoxy edges and trace the wood’s profile. Then, cut the paste out with scissors to get precise edges,

  • Let the Wood Dry

Give the epoxy 24 hours to dry, then it is ready for sanding, priming, and painting.

Besides, it is advisable to prime and paint the wood if you’ll use it in outdoor applications. Otherwise, the sun will accelerate wear and tear.

Strategy Two: Patch With a Wood Filler.

  • Prepare the Wood Filler

Pour a three-inch diameter circle of wood filler into a non-porous material. 

Also, put the formula on a glass or plastic piece to keep it from sticking to the lumber. Then, ensure the circle is a half-inch thick to deliver enough to mix.

Next, squeeze the hardener tube without removing the cap. The hardening agent separates in the tube. Thus, firmly squeeze it with your fingers for better mixing.

The other step is to pour a three-inch hardener strip on the filler and mix. Then, stir the formula with a putty knife for about two minutes.

The mixture should deliver a light red hue when ready.

Further, the wood filler has a ten-minute working time. Hence, only use small potions at a time.

Also, keep the formula spread thin to give it a longer working duration.

  • Apply the Wood Filler

Use a scraper or putty knife to apply the formula. Please use firm pressure to deliver uniform coverage.

Spread the filler two inches beyond the rot problem. Continue spreading until you get the desired thickness.

  • Let the Filler Dry

Give the wood filler 30 minutes to dry. Generally, it sets within half an hour at under 24 degrees Celsius.

Also, the project needs as little as ten minutes to set during warmer temperatures.

Strategy Three: Remove the Rotted Area

  • Claw Out the Rotted Lumber

Use a claw hammer in this step. Further, place the hammer’s claw at the rot’s base and apply pressure when pulling it towards you.

Remove as much rotted wood as possible without damaging the healthy parts.

In addition, please do not force the lumber during the process. Only remove soft and rotting material.

  • Use a Router for Remaining Rotten Wood

Use a router featuring a V-shaped bit for a better result. In addition, hold the device, so the bit is 3.2 mm from the wood’s back edge.

Use short back-and-forth motions to grind away remaining rot spots.

Grind the lumber until you reach solid and healthy wood. Also, harder wood is more challenging for the router to penetrate.

Lastly, remember that the wood may start rotting again if you leave any rot.

  • Sand and Paint the Surface

Unfortunately, most patching products do not stick to existing paint. Therefore, it is prudent to remove the finish.

Use coarse sandpaper, say around 60 grit, or a paint scraper to remove residue rot.

Next, apply an even pressure amount and work in circular strokes to deliver a more uniform surface.

Then, remove all dirt, primer, and rust to facilitate better adhesion.

  • Apply a Wood Restorer

Apply four to six wood restorer coats to the affected area. Also, use the provided paintbrush to apply the formula.

Let the product set for two minutes before adding the next coat and two hours before proceeding to the next step.

Also, wear rubber gloves when handling the formula. Otherwise, it will cause skin irritation.

Strategy Four: Make a Wood Patch

  • Cut the Lumber

Use a Japanese hand saw to make smooth and straight wood cuts.

Next, apply consistent pressure to the accessory and pull it down at a 45-degree angle.

Repeat the cut until you remove the rotted wood by hand. In addition, mark the line you want to cut for a straight edge.

  • Trim the Patch

Generally, cedar is a typical patch option for most projects. It is rot-resistant and guarantees a durable repair.

So, trim a cedar piece to the hole’s size. Further, use the saw to cut the patch to the correct size.

However, ensure that the lumber fits snugly in the rotted area. Otherwise, the board will not fit flush with the structure if it is too loose.

  • Wipe the Surface

Dampen the exposed lumber surface with a wet cloth. Furthermore, the glue in question activates with moisture.

Next, use the wet rag to rub where you’ll be positioning the patch.

  • Apply a Polyurethane Glue and Place the Patch

Squeeze the glue from the container and apply it directly to the wood. Then, spread it to cover the exposed area.

Press the patch against the lumber and let the glue set.

Polyurethane glue usually foams and expands before hardening. Therefore, it quickly fills small gaps.

However, please avoid touching the uncured glue with bare tools or hands. It is extremely challenging to remove.

  • Fasten the Patch

Hold the patch in place by drilling two screws on the patch’s sides.

Further, use long screws that reach the baseboards. Then, place one side of the patch to hold it as the glue sets.

  • Sand Excess Glue

Wait for about six hours and sand the excess glue from the patch.

In addition, the polyurethane glue needs six hours to dry thoroughly. Therefore, wait for the recommended duration. 

Then, level the wood with fine-grit sandpaper.

Strategy Five: Sand and Paint the Patched Wood.

  • Sand the Surface

Smooth the patch with a sanding accessory. And ensure that its edges are flush with the existing wood.

This way, you guarantee a uniform appearance. Start with a coarse paper, say 60 grit. Then, work down to fine-grit sandpaper, like 200-grit, for a smooth finish.

  • Choose the Correct Finish

Use a matching finish if the original surface has a stain or paint. Next, paint the stain or paint coat and let it dry.

Please avoid overlapping layers of the existing finish. Otherwise, the color will appear darker in the repaired area.

Moreover, wood filler patches may stain differently from the actual wood. Thus, test the finish on a small, inconspicuous area before application.

  • Apply the Primer

Paint at least two wood primer layers when working with painted wood.

Also, use multiple thin coats of white or grey primer for an even application. Then, give the formula 10 minutes to dry before subsequent coats.

Alternatively, use a spray primer to guarantee a more uniform layer and avoid brush strokes.

  • Apply the Finish

Apply a paint coat after the primer dries. Ensure you keep stirring the paint for easier handling.

Paint thin, even layers with a paintbrush. Also, use long strokes covering the entire wood length. Finally, the paint should cure in ten minutes unless the area is humid.

Here’s How to restore Rotting Wood:

What Is Natural Remedy for Dry Wood Rot

Thankfully, you do not always have to use expensive commercial products. We have various simple and safe Do-It-Yourself techniques to remedy dry rot issues.

They include

  • Olive Oil and Lemon

Mix three olive parts with two lemon juice parts. Then, decant the mixture into a spray bottle.

Alternatively, use a polish rag to apply the formula. Only ensure you deliver complete coverage.

  • Coconut Oil

Coconut oil is another option when dealing with wood rot at home.

Wipe the lumber with a damp cloth and let it dry. Then, rub coconut oil evenly on the entire surface.

The formula revitalizes, replenishes, and protects lumber.

  • Oil and Vinegar

Mix some canola oil and vinegar to deliver a brilliant wood sealant. Further, the formula protects wood pieces from wear, moisture, and burrowing insects.

Oil and vinegar also revitalize the surface. You can also go for homemade dry rot treatments. They include borate and glycol treatments.

  • Borate Dry Rot Treatment

Prepare borax and boric acid according to the manufacturer’s instructions.

Mix 40 percent boric acid and 60 percent borax. Then, stir the mixture over low to hear until you remove all crystals.

However, use this formula only at temperatures above 40 degrees.

  • Glycol Dry Rot Treatment

This treatment process utilizes borax, boric, and glycol antifreeze acid. Mix these crystalized compounds with water according to the product directives. 

For example, use a 50:28:22 percent ratio, that is, glycol, borax, and boric acid, respectively, during mixing.

Next, pour the solution into a jar and heat it gently. Monitor the solution with a candy thermometer. Let it remain at 260 degrees until you can all crystals dissolve.

Finally, let the formula cool before application.

Does Vinegar Stop Wood Rot?

White vinegar stops lumber rot as it is a fungicide. Besides, it has antimicrobial properties, keeping wood-eating organisms at bay.

Fungi need a zero to 5.5 acidic environment. So, vinegar hinders its growth by altering the wood’s PH level.

However, adhering to the correct steps when applying the formula is advisable.

The recommended procedure is as follows

  • Dry the Wood 

Dry the material by running a dehumidifier or repairing any plumbing and moisture leaks. 

This way, the scenario will not reoccur after applying the formula.

  • Treat the Lumber

Confirm that the surface is dry and apply the vinegar. The solution increases the wood’s PH level and interrupts fungi growth.

  • Monitor Your Work

Monitor the Lumber for further decay signs. Further, since the wood has a rot damage history, it has an increased rot occurrence risk.

Nonetheless, it is prudent to stop fungi at early rot development stages. Some rot types are hard to eradicate and keep recurring.

Frequently Asked Questions

  • Is Rot the Same as Mold?

Rot is not the same as mold. Although mold and mildew are fungal and love wet lumber, they only cause discoloration, not wood rot.

On the other hand, these organisms leave the lumber susceptible to rot as they make it more absorbent.

Further, wood rot is more dangerous by mold. The latter does not break down the lumber.

Thankfully, it is easy to spot differences between wood rot and mold. For instance, mold manifests as discoloration, usually white or black.

Conversely, wood rot presents itself as decay.

  • How Do I Treat Wood Rot Fungus? 

Establish and fix the sources of moisture. Next, dig out the decaying lumber to prevent further damage. Apply dilute bleach to kill the wood rot and prevent it from spreading.

Finally, fill the crevices with a wood filler after the wood dries. Also, refinish them to complement or match the surrounding surface.

  • How Do I Stop Dry Rot on Wood?

You can stop the rot on lumber using boric acid. Apply the formula to the wood during construction or when an active decay fungus is stopped.

Mix boric acid with the recommended portions. Then, pour or spray it on the decaying lumber parts. Let the material soak in the acid and cure thoroughly.


Wood rot causes multiple structural problems indoors and outdoors. Besides, you cannot reuse rotted lumber.

So, you’ll have to replace it, resulting in more repair expenses.

Fortunately, although we do not have foolproof strategies for treating wood rot, some chemicals prevent its occurrence.

In addition, bleach is a famous, most effective anti-rot solution for wood. Therefore, read the discussion above for more insight.

Will Bleach Stop Wood Rot?

Household bleach is a potent disinfectant that kills and stops fungi growth. As a result, it helps to curtail rot.

However, chlorine bleach causes excessive wood pulping and alters its color. 

Thus, diluting the formula with water before applying it to the affected lumber is advisable.

Image of a woodworker wearing hearing protectors for woodworking

Tyron Otieno

Tyron is an avid woodworker and writer. He founded this website to help other woodworkers, whether hobbyists or professionals by sharing his knowledge and experiencie after a decade of woodworking.

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