What You Need to Know About Wood Deck Rot

Moisture can do a lot of damage both inside and outside of your home. To keep your outdoor living space in great shape, it’s important to be aware of the signs of wood deck rot. Repairing weak or worn deck boards that have been damaged by moisture will keep your deck safe, secure, and attractive for years to come.

Why your deck could be rotting

There are several reasons that your deck boards could be suffering from wood rot. Identifying the cause will allow you to come up with the best solution for repairing the damage and preventing it from happening again in the future.

Standing water

After rain showers or snow, water can collect and puddle on older or worn deck boards. You may notice certain boards that have small dips or craters where water can puddle. A slanted deck can also cause water to run down and pool up in an area instead of running off. If you notice small puddles, it’s probably time to replace those deck boards.

Untreated wood

To keep your deck durable and less inviting to insects, you should build it with treated lumber. Untreated wood will rot much more quickly, especially if left without a stain or sealing.


Termites can turn your deck into their own personal feast before moving on to other wooden elements of your home’s structure. While they prefer natural wood, they will go after treated lumber, too. If you suspect termites on your property, it’s best to call a professional exterminator to take care of them before repairing your deck.

Debris build up

Debris that blows onto the deck and is left sitting can trap moisture. This leads to mold and mildew growth, which damages and weakens the wood beneath. Sweep debris like leaves and branches off of the deck frequently.

Freeze-thaw cycle

The natural freeze-thaw cycle is unavoidable in many regions, and it can cause issues for decks. As moisture gets in between the small cracks in wood, it seeps down, freezes in cold temperatures, and then thaws out again. This constant presence of moisture and the creation of cracks will weaken the deck boards. The cycle plays out over many seasons, so the damage can occur very slowly and may go unnoticed for years.

How to do a deck inspection

When it comes to wood rot, it’s important to know what to look for and how to find it. A quick deck inspection will help you locate any signs of water damage. Do a visual check of the deck boards, both where you walk and underneath of the deck. Look over the stairs, railings, and the footers. An easy way to spot problem areas is to do an inspection right after it rains. This will allow you to see where water may collect on boards or in certain areas.

What to Do

Make any necessary repairs by replacing damaged deck boards with new treated lumber. A moisture resistant stain or sealant should be applied to protect the new wood. Be proactive about clearing off debris and leveling out any areas where water pools and puddles. A quick visual inspection in every season will help keep wood deck rot at bay.


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