Will bleach stop wood rot? If you’re wondering whether it will work efficiently or be oversold, sit tight for the details.

One of the major threats to wood is rot –mostly wet or dry rot. Therefore, it’s important to learn the various options for stopping wood rot should it come to it.

This blog post will show you how to treat wood rot with bleach, other wood rot stopper alternatives to consider, and most importantly, how to prevent rot.

Let’s jump right in!

Will Bleach Stop Wood Rot?

Yes, bleach will stop wood rot from spreading and recurring in the future. It is a cheap yet effective method of treating wood rot. Apply a minimum of two bleach coats to the affected wood and the surrounding parts. For better results, ensure the treated wood remains dry.

What Causes Wood to Rot?

Fungus spores are the main cause of wood rot. The fungus spores germinate and thrive, feeding on damp wood tissue. If left untreated, the rot fungi will spread, make wood soft and cause major deterioration.

Types of Wood Rot

Understanding the various types of wood rot will enable you to pick a suitable treatment option. 

1. Dry rot

Dry rot fungus requires at least 20% wood moisture to germinate and colonize the wood. Unlike other types of rot, dry rot can continue to feast on wood even after it dries out.

What does dry rot look like?

Dry rot early signs present a spread of what looks like white cotton wool on the affected wood surface. A slightly advanced dry rot will present a characteristic cuboidal cracking –the wood cracks in tiny squared pieces.

When the rot situation is advanced, you’ll notice the growth of mushroom-like fruiting bodies among the fungus spores. This is when the fungus has fed on all the fresh wood, and timber is on the verge of crumbling.

What causes dry rot in wood?

Dry rot fungus inhabits timber presenting a conducive environment for growth –at least 20% moisture. 

Dry rot treatment

Remove rotted wood from its original place. Cut the rotten wood and a few inches of the sound wood beyond the last visible spots of fungal growth. 

Next, remove all the fruiting bodies, hyphae strands, mycelium, and any visible fungus spores. Finally, use a stiff brush to clean and remove surface growth from the wood and the surrounding wall.

Liberally treat both the fresh and old wood using dual-purpose dry rot treatment liquid. This fungicide is specially formulated to kill dry rot spores and stop further rot while preventing wood rot in the future.

Apply the fungicide on neighboring masonry or concrete –two coats will suffice. Also, ventilate the area and run a dehumidifier to remove excess moisture from the wood.

2. Wet rot – White rot

Wet rot requires a high moisture content of at least 50% to infest and colonize wood. The source of this wood moisture may vary, but while it remains the same, fungus spores will feed on the lignin and leave the wood decayed.

What does wet rot look like?

You will notice a dark wood spot with wet rot, darker than the surrounding parts. You can also expect the wood to look shrunken and feel soft and spongy with brittle cracks. Wet rot will also present fungus growth and a damp, moldy smell –like rotting soil.

Wet rot treatment

Identify the source of dampness and fix it. Assess the degree of damage and, where possible, separate the rotting wood from the rest.

Scrape the decayed bits and treat the rotting wood with wet rot fungicide. This fungicide will kill wet rot and prevent them from spreading.

Ensure the wood soaks up the treatment and dries completely before the next coat. Remember to treat the unaffected wood, too, to prevent future wood decay. 

You will need to replace boards that are too damaged with pre-treated ones. You can contact an expert if the project feels too overwhelming to DIY.

3. Brown rot

Will Bleach Stop Wood Rot

Brown rot results from wet rot fungus feeding on the sugars and cellulose of some wood species when it can’t digest the lignin. This gives the decayed wood a brown appearance, resembling the color of the affected wood. 

Using fungicides like boron solutions, ethylene glycol or propylene glycol, tea tree oil, or hydrogen peroxide, you can defeat brown rot.

How To Stop Wood Rot Using Bleach

Bleach kills the wood destroying fungus and stopping it from recurring. Chlorine bleach will also remove rot stains from the surface and brighten the wood color. Here’s how to use it.

Tools & Materials to stopping rotting wood

  • Gloves
  • Nose mask
  • Goggles
  • Stiff brush
  • Bleach
  • Cotton ball or spray bottle
  • Wood filler
  • Putty knife
  • Sandpaper
  • Wood finish

How to Treat Wood Rot in 5 Easy Steps

When you notice wood rot in your home, follow the following steps to fix rotten wood.

Step 1: Identify the source of the moisture

Before you treat decay fungi, first establish the source of moisture seeping into the wood and fix it. Check for leaking windows, plumbing, or washing machine leaks, penetrating or rising damp as the main source of moisture.

Once you figure out the cause of the moisture, you can estimate the degree of rot damage. Prevent future rot by eliminating the source of moisture, repairing leaks, and running a dehumidifier to dry the excess moisture on the wood surface. 

Step 2: Prepare the wood for bleach treatment

The parts of the house most susceptible to wood destroying fungus are roofs, decking, windows, and door frame area. Luckily we have a guide on how to repair a door frame with wood filler in case you encounter signs of damage. If the rot is spread over several boards and the damage is beyond repair, replace them with pre-treated ones.

However, if the damage is repairable, scrape out the rotted pieces on the surface, corners, and crevices using a chisel. After digging out all the decayed wood, brush the wood further using a stiff brush to eliminate all the rot fungi.

Step 3: Apply bleach to the affected spot

Bleach is quite potent and may irritate the skin, eyes, or nasal pathways. Therefore, use it in a well-ventilated space before opening the can. Also, wear protective gloves, a respirator mask, and safety goggles.

Dilute chlorine bleach with water in a plastic container. Soak a cotton rag in the solution and rub it on the rotted wood. Also, apply bleach to the neighboring parts of the rotted spot.

Let the bleach soak in. Rinse off excess bleach with warm water and let the wood air dry. You can also transfer the diluted bleach into a spray bottle and spray it on the affected area, especially if it covers a large area.

Step 4: Apply wood filler to the crevices and a finish coat

Once the treated wood is completely dry, you need to fill the crevices from extracting soft and rotting wood.

You could use several types of wood fillers to repair wood: Bondo wood filler, polyester wood filler, epoxy wood filler, etc. We’ll use polyester filler because it is especially perfect for rotted wood.

Mix polyester wood filler and apply it to the crevices using a putty knife. Over-apply the filler because it shrinks a little when dry.

Once it dries, you can sand it to match the unaffected wood areas. Afterward, prime and paint or apply a finish of choice.

Step 5: Maintain wood in good condition.

After all the efforts to kill wood rot and refurbish the rotted wood, it should be easier to keep wood in good condition.

Ensure there are no more leaks in the area or any in another part of the house. Also, use a dehumidifier to keep wood dry if you’re living in a highly humid area. 

Other Wood Rot Stopper Alternatives

Like bleach kill wood rot, boric acid and ethylene glycol are excellent rot stopper alternatives.

Boric acid

Boric acid is powerful enough to kill an active decay fungus and prevent it from growing and spreading on wood. In addition, boric acid is used to treat wood during construction to prevent future wood rot. 

You can buy the water-soluble borate products –Tim-Bor, or borates dissolved in ethyl glycol –Bora-Care.

Mix borax, boric acid, and water in a saucepan over low heat. Once the crystals dissolve, pour the mixture into the wood. This will bind and dissolve water while also killing the rot fungus.

Ethylene glycol

Ethylene glycol or propylene glycol readily exists as automotive antifreeze. However, glycol is potent and most toxic to fungi spores and other organisms; use it cautiously.

Ethylene glycol antifreeze stops wood rot by penetrating the fibers and killing fungi spores. In addition, this product lasts a while in the wood, preventing the recurrence of wood rot.

The best part is that you can brush it over paint, varnishes, and oil finishes, which won’t damage the finish.

Wood Treatment To Prevent Rot

Before joining the wood rot repair league, do your best to prevent fungi spores from setting up camp in your home. Here’s how to navigate the process.

  1. Apply wood hardener, wood preservative, or boric acid to wood if it’ll be buried in the ground. Here are the best wood hardeners you can choose from.
  2. Repair plumbing leaks and any other water inlet to keep wood from pools of water.
  3. Remove old caulk and seal all the cracks around exterior windows and doors using fresh caulk.
  4. Clean gutters regularly to prevent blockages which will cause water to run over the gutter and onto the side of the house, keeping it wet.
  5. Keep the doors away from the rain by covering the entryway.
  6. Run a good dehumidifier in the room with the most humidity to ensure the wood in the room doesn’t encourage the infestation of dry rot fungus.
  7. Sweep away pools of water from outdoor decking when the rain stops.

If you’re installing fence posts, here’s how to protect wood posts in the ground


How to stop wood rot from spreading?

First, remove the decayed softwood particles using any sharp tool at your disposal. Next, use a stiff brush to remove every bit of rotten wood. Finally, apply bleach or boric acid to the affected part and let it dry completely. Then, repair the crevices with wood filler.

How to stop dry rot on wood?

Stop dry rot on wood using boric acid. You can apply it on wood during the construction stage or stop an active decay fungus. Mix it with the recommended proportions and pour or spray it on the decaying wood. Let the wood soak in the acid and dry out fully.

How do you treat wood rot fungus?

Identify and fix the source of moisture. Next, dig out the decaying wood to prevent further damage. Finally, apply dilute bleach spray to kill and prevent wood rot from spreading. Once the treated wood is dry, fill the crevices with wood filler and refinish them to match the neighboring wood surface.

What is the best dry rot treatment spray?

The best dry rot treatment spray is Nisus BORA-CARE. This product is efficient against wood decay fungi and other wood pests. It is easy to use, doesn’t have a toxic smell, and doesn’t discolor the wood. It can treat wood during construction or an already existing structure. Bora-Care guarantees wood protection for over nine years. Unfortunately, it comes in 1-gallon jugs, so transfer it into a pump sprayer and spray away!

How to stop wood-rotting outside?

Stop wood-rotting outside by treating wood using boric acid or wood hardener. It also helps seal all sides of the wood with products meant for exterior use. In addition, ensure proper ventilation around the rotting wood and avoid water pooling around. Use pressure-treated or decay-resistant wood outside. Also, use the right pressure-treated lumber for ground contact whenever possible. 

Does wood rot spread?

Yes, wood rot can spread throughout the wood if left untreated. Provided the wood has a minimum of 20% moisture level, the wood-destroying fungi will continue growing and spreading –feeding on wood.

How to stop wood rot on deck?

Stop wood rot by repairing the damaged board. First, scrape off the brittle pieces, and then soak the spot with boric acid or bleach. Let the wood dry completely, and then fill the holes with wood filler. Finally, sand and apply a finish coat. Replace the damaged board if it’s beyond repair.

Can water-rotted wood be repaired? 

Yes, you can repair water-rotted wood. First, remove the rotting pieces on the wood board, decking, or rotted door frame. Then, ensure the wood is dry before applying filler like polyester wood filler. Wood filler will patch up the gaps and reinforce the wood’s strength. Sand over the filler once it dries, and then refinish the wood.

Can wood rot?

Yes, wood can rot in different forms, provided it is wet or moist and stays that way. Wood can absorb moisture from direct contact with the ground, a water leak, or exposure to a highly humid environment. Only dry wood can’t rot if it remains dry.

How to tell if wood is rotted?

How to tell if wood is rotten; the first sign is a dark stained spot, appearing darker than the adjacent parts. You could also lookout for a white powdery deposit on the surface. Still, you may notice that the wood feels soft and almost spongy to the touch. It could also look cracked and brittle or significantly smaller than the rest of the timber.

Read also: Does pressure-treated wood rot?

Final verdict: Will Bleach Stop Wood Rot?

Yes, bleach will stop wood rot. Dig out the weak wood and then drench the part in bleach. Wipe excess bleach and let the wood dry. Fill the crevices with wood filler, and voila! You have a brand new wood. 

Although treating wood rot appears relatively easy, it is way easier and smarter to prevent rot from occurring in the first place. So take the tips we’ve mentioned and spare yourself future rot repairs.

Happy woodworking!

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