Wet wood is the first requirement for wood rot to begin. The moisture content of the wood has to exceed its Fiber Saturation Point (FSP), which is typically around 30% or more water content. Next, wood decay spores, which are constantly being blown around in the wind, settle on the moist wood surface. When the temperature is warm enough, the spores germinate into tiny fungus “plants” with root-like hyphae tubes that penetrate the wood and secrete enzymes, which soften the wood and make it easier for the fungi digest. The fungi multiply to form a colony and, under the right conditions, they can expand rapidly across the wood.

 While wood rot may seem like just a nuisance, advanced decay can cause structural failure. Replacement wood needed to repair wood rot fungi damage accounts for 10% of the annual wood production in the United States, according to an Ohio State University study.

Three Common Types Of Wood Rot

Brown Rot - This type of decay causes the wood to break down into brown cubes that split against the grain. It is sometimes called “cubic wood rot.” Advanced stages of brown decay result in dry, powdery wood that is unable to support much weight, and crumbles easily.

White Rot - This type of decay appears whitish, stringy and mushy, and tends to be more common in hardwoods.

Dry Rot - A misnomer, this term has been used to describe decayed wood that has since dried and ceased decaying. Some people may erroneously assume that the wood is still in the process of decay. Moisture is required for wood decay to occur, so no literal “dry rot” exists.

 How To Prevent Wood Rot

•• Keep wood sealed with a coat of paint in areas of direct weather exposure. Caulk any joints or cracks the wood surface that might hold driven rain.

•• Avoid installing wood in a configuration where rain water will sit on the surface of the wood for extended periods of time instead of draining away. These spots are called “water traps” in the carpentry trade and professional builders try to avoid them by giving any horizontal surfaces, such as a window sill or top surface of raised door or window trim, a slight incline so that water runs off.

•• Maintain adequate ventilation in the crawl space under a home. Moisture arising from the soil will create a humid under-floor environment unless adequate cross-ventilation openings are installed.

•• Install preservative-treated wood where in contact with, or near, the ground. 

•• Make sure the grading of the soil around your home slopes away from the walls, to avoid water puddling under or next to the home.

•• Keep any wood siding a minimum of 6-inches above the ground and don’t let leaf debris accumulate around the base of siding.

•• And last, installing gutters will dramatically reduce wood rot problems on many homes with wood siding, especially the rot caused by rainwater splash-back onto the bottom 12-inches or so of wall.

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To learn more about TERMITES, WOOD ROT AND OTHER PESTS see these blog posts:

• Is the WDO (termite) inspector allowed to poke holes in my wood siding and trim? 

• Do carpenter ants cause structural damage to houses in Florida? 

• How long before closing can you have a WDO (termite) inspection done?

• How long does Bora-Care® last? 

• Where are the most common places to find wood rot on a house?

• Why is it a mistake to store lumber in the crawl space under a house? 

• Does the presence of carpenter ants in a house indicate that there are probably also termites? 

• How do termites infest a house and remain hidden while doing major damage?

 • Are homes in Florida required to have termite protection? 

• If termite damage appears to be old, does that mean that termites may no longer be present?

• What does roach poop (fecal pellets) look like? 

• When do termites swarm in Florida? 

• Does a recent termite company inspection sticker mean there are no termites? 

• Can a mobile/manufactured home get termites?

• Do I have to tent the house if I have termites? 

• What is the difference between a subterranean termite and a drywood termite?

• What are the green plastic discs in the ground around the house? 

• Is wood rot found on a home inspection considered serious? 

    Visit our TERMITES, WOOD ROT AND PESTS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.