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What are wet rot and dry rot?

Monday, November 21, 2022

Your outdoor deck is a place where you and your family can enjoy your weekends, but after years of use, traditional wood decks can show signs of rot. Deck rot not only affects use but can also pose a safety hazard to you and your family. Deck rot is divided into dry rot and wet rot, and they are generated under different conditions and for different reasons. Next, let’s learn about the causes of deck rot and how to prevent them.

What is wet rot?

Wet rot is the rot that occurs on untreated wood that is often exposed to water or high humidity. The fungus likes to grow on damp wood. Although most wood decks are made from pressure-treated wood, it is still possible for wet rot to occur. For pressure-treated wood decking, the most vulnerable areas are where the wood has been cut and left untreated, and where water has accumulated or seeped into cracks.

Fungal spores begin to grow when the moisture in the wood exceeds 30%. If you don’t stop the growth of the fungus, it can spread to the structural parts of the deck and cause it to collapse.

outdoor decking boards

Early signs of wet rot

What we need to do for wet rot is to detect and treat it early. To detect wet rot as early as possible, please note the following points.

  • Outdoor decks begin to develop a damp, musty odor
  • Wood begins to crack and soften
  • Wood deck boards move or “bounce” when you walk on them
  • Wood plywood begins to discolor or become brittle
  • Fungal growth that is easily visible

Causes of wet rot

Wet rot can occur in buildings for a number of reasons, such as bad roofs and leaky pipes. For wood decks, common causes include poor drainage that makes decks, railings, or posts wet. Leaky gutters or downspouts, wet floors, and a build-up of leaves and other tree debris on the deck.

How do I deal with wet rot?

Wet rot can usually be addressed in two ways: by blocking the source of water and by repairing or replacing rotted wood. The severity of the rot and the extent to which it has spread will determine the cost.

Once you have stopped the source of water that is causing the rot, you may be able to treat and get rid of the rot yourself. Unless the damage to the wood deck is very severe, such as severe damage to structural sections. After stopping the source of water, the next step is to find all of the rotted wood. You may be surprised at the extent of the rot once you begin an in-depth inspection, but don’t be afraid to get rid of it.

This task may also be a good time to think about how to avoid problems. When building a deck, putting waterproof butyl tape on joists, beams, edge joists and sill plates is one of the best ways to keep water out. It’s also a good idea to regularly check your wood deck for rot. The sooner you notice it, the easier and cheaper it will be to fix.

What is dry rot?

Dry rot can appear on some older decks. When a wood deck starts to discolor or soften and may flake and fall apart when exposed to moisture, then it may have dry rot. You can check the wood for soft spots with a screwdriver. Even pressure-treated lumber can rot and die in some cases. If the deck is too wet and there is water on it, it will rot and fall apart. Since dry rot is a fungus, it can spread through a deck like cancer. Dry rot is caused by microorganisms that eat away at the wood’s cellulose, making it brittle. In addition, dry rot can also attract wood-eating insects, such as termites, which can make the problem worse.

Why does dry rot occur?

Moisture is the enemy of wood decking because it gives mold and fungus a place to grow and multiply. If your outdoor deck has been exposed to a lot of water, dry rot may start to happen. When these things happen, it doesn’t take long for wood-eating fungi to get in and start making your deck unsafe and unstable.

To prevent rot, you must prevent your deck from being exposed to moisture. You can do this by creating a cleaning schedule and checking the area frequently. An annual cleaning will keep your deck looking great cosmetically, but more importantly, it will help you avoid costly repairs like a rotting deck by removing the dirt, mold, and bacteria that are starting to build up. And, having your deck inspected by a professional every two years can help you find any sources of water and figure out how to fix them before they cause serious damage to your deck.

Causes and Signs of Deck Dry Rot

Moisture, mold, and insect damage can cause untreated wood to rot and break down over time. The most common and serious rot problem is caused by sill plates that are not properly installed, allowing water to enter the walls. Rot is more likely to occur because the framing of your home is not treated. If the rot has spread to your sill plates, you may need to replace the entire deck. You may also need to repair certain parts of the wall. If only a few joists or a few pieces of the deck are rotting, you may be able to just take them out and replace them.

How can I tell when I have dry rot on my deck?

If you have a painted wood deck, you may not be able to observe it directly. Then you can use a screwdriver to check the wood for soft spots. You can also tell if your wood deck is rotting by looking for the following signs of dry rot

Look for soft spots around posts that touch the ground, as these areas are usually more susceptible to moisture.

Look for long streaks of gray mold or darker-looking wood, as these are signs of dry rot.

If you see insect damage, this could be a mix of insect damage and dry rot, as termites and other wood-eating pests are attracted to dry rot.

Check the area around the dry rot for sources or causes, such as leaking pipes, broken gutters, problems with the sprinkler system, or any other ground where water may be pooling

Repairing deck rot

If you find dry rot on your deck, first find the cause of the dry rot. This could be caused by a leaking water line, the way the gutters are set up, uneven boards that are causing water to pool, problems with the sprinkler system, or other things. Finding the source of the water and fixing it will be your best way to stop the rot in the future. You will then need to remove and replace the affected section immediately to stop it from spreading.

When replacing rotted deck boards and cracked deck posts, it is important to carefully inspect the damaged area. Make sure to check all areas immediately adjacent to the rotted wood, as even the first signs of rot will eventually spread to your new fixtures. Once you have finished replacing the rotted deck, you will need to seal or stain the wood deck to prevent moisture from entering. If you’re not sure how to spot or repair a rot spot on your deck, you should call a professional.

What is the difference between wet and dry rot?

Both wet rot and dry rot are caused by excess moisture in the wood. However, dry rot comes about because moisture is usually not evident. In fact, dry rot can start at lower moisture levels (>20%) than wet rot. Also, once dry rot starts, it absorbs moisture from the wood while eating away at the cellulose. It can spread in the absence of any other source of water. Because of this, dry rot is considered to be the worst type of fungal rot.

Simply put, both wet rot and dry rot can cause serious damage to wood. However, they differ in four specific ways.

  • Wet rot requires more water than dry rot to start growing.
  • If you remove the source of water, the growth of wet rot will stop.
  • Dry rot does not need a steady source of water to spread because it uses the wood’s own water to grow.
  • Because dry rot spreads more easily, it is also more likely to require professional help.

How do I prevent deck rot?

For traditional wood decks, pressure-treated wood does prevent rot. However, in some cases, it can still decompose. This is because pressure-treated wood is not completely waterproof. Without a sealer, pressure-treated wood will absorb and lose water, causing it to swell and shrink, crack, warp and buckle, and essentially fall apart over time. That’s why it’s important to clean and apply a water repellent to your pressure-treated wood deck every year. So, is there a more trouble-free and corrosion-resistant material? The answer is yes.

Composite Decking that won’t rot

Composite decking is a new eco-friendly material that lasts longer and is easier to maintain. Composite decking is non-rotting due to the nature of the material. It is stronger than wood, lasts longer, and requires very little maintenance. In addition, decking made of composite material does not require staining or painting. Most composite decking materials also come with a long-term warranty from the company that makes them.

If you have any questions about composite decking materials, please feel free to contact us. In addition, we can provide you with free samples of composite decking so you can get a better understanding of our products.

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