Will Pressure-Treated Wood Rot?

Take some of the pressure off

wooden deck in backyard
Photo: Bryan Chavez/ istock/ Getty Images
wooden deck in backyard
Photo: Bryan Chavez/ istock/ Getty Images
  • In the right conditions, pressure-treated wood will rot due to fungi.

  • Wood rot can happen due to manufacturing defects and prolonged moisture exposure.

  • Fortunately, you can take steps to repair rotted wood and prevent future rot from occurring.

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Pressure-treated wood has a few advantages over traditional wood—but will pressure-treated wood rot? The simple answer is, surprisingly, yes. However, that doesn't mean that the wood you used to build a deck or frame your home has to rot. Learn why pressure-treated wood rots, what to do about it, and how to prevent it from happening in the future. 

What Is Pressure-Treated Wood?

close up of wood floor deck
Photo: hudiemm/ Getty Images

Pressure-treated wood undergoes a process that injects preservatives into it using high pressure. The preservatives protect the wood from insects and moisture while also slowing down the natural decay process.

Since it resists moisture and insects, pressure-treated wood is often recommended for use outdoors, particularly in decks and porches.

Why Does Pressure-Treated Wood Rot?

If pressure-treated wood has undergone a special treatment to prevent rotting, how is it possible that it can still rot? The key thing to remember is that the wood treatment process isn't perfect. It can slow down decay and offer the wood extra protection, but it won't make the wood impervious to damage. 

Several factors can cause pressure-treated wood to rot, including:

  • Prolonged exposure to moisture or wet conditions

  • Limited ventilation or drainage around the wood

  • Damage to the wood, which allows rot-causing fungi to get in

  • Improper treatment techniques

  • Advanced age

Often, a common cause of rot in pressure-treated wood is a type of fungus, which can get into the wood through cracks or openings created by screws or other fasteners. Over time, the fungus can spread, causing the wood to rot.

How to Repair Rot

You may be able to repair dry rot or other types of rot in pressure-treated wood, as long as the damage isn't too extensive. Repairing wood rot involves removing the damaged sections of wood and replacing them with wood filler. 

If you're concerned about the extent of the rotting or don't feel comfortable making the repair yourself, working with a professional water damage restoration company is the best option. This is especially true if there are any signs of structural damage due to the wood rot. In that case, you will need to repair a large section of the affected wood.

Angi Tip

Though the terms are used interchangeably, wood rot and dry rot have different meanings. Wood rot is a broad term that describes various types of fungal decay in wood, while dry rot is a specific type of wood rot caused by the fungus Serpula lacrymans. Dry rot can thrive at a low moisture level and spread rapidly across plaster and even masonry to infect new areas of wood.

Morgan Rousseau
Content Editor, Angi

How to Prevent Wood Rot

The best way to prevent or stop wood rot is to get rid of the fungus and keep it from coming back. To do that, you'll need to find the source of fungi's food, which may be a leak or a lack of ventilation. Keeping the wood as clean and dry as possible will help to keep fungi, and the rot they cause, at bay.

Frequently Asked Questions

With the right care, pressure-treated wood may provide up to 40 years of usable life. But how long pressure-treated wood lasts depends on how it's being used and cared for. The wood used for flooring or decks tends to have a shorter life span than the wood used for poles or beams. The quality of the wood and the climate in your area also influence how long the wood lasts.

The signs of rot depend on the type. Dry rot looks like cube-shaped cracks with a fluffy white, cotton-like texture. Wood with dry rot may also have a strong, musty smell. 

Signs of other types of rot include wood that looks mushy or has black spots. The wood may crumble or give way when touched.

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