Is Wood Rot the same as Mold?

Is wood rot the same as wood mold and why should you understand the difference? Whether you have vinyl siding on your home or aluminum soffits have been installed, the structure is essentially made of wood. Typically your home includes wood rafters and often types of exterior finishing such as doors, trim, soffit and fascia. Both wood rot and mold are the result of fungus growth, but only one of them does actual damage.

Wood Rot

When wood becomes wet in a temperate climate like Vancouver’s, it is vulnerable to fungi. If the moisture content of the wood is 20 percent or below, there is little danger of fungus growth. However, above 20 percent and wood can become a breeding ground for fungi. Because wood is made up of cellulose and lignin, fungi basically sees wood as the perfect food source. And this is what causes damage to the wood, weakening it. Left untreated or unrepaired wood rot can eat right through a beam, section of siding, etc. until it collapses.

The three main types of wood rot are:

Brown rot – This type of wood rot turns wood a dark brown colour and typically causes it to crack against the grain. It can cause wood to split and then crumble. When advanced, brown rot removes the nutrients from the wood so completely, it becomes powdery. Because of its colour, brown rot is sometimes erroneously referred to as dry rot.

White rot – Once it has taken hold, white rot causes the surface area of the wood to become white or yellowish. If left untreated, it can eventually make the wood feel spongy.

Soft rot – As its name implies, soft rot gives wood “soft spots.” It typically attacks wood shingles (used for roof or siding) in wet climates.


Both mold and mildew are also fungi that thrive in damp or moisture-laden environments. While mold or mildew covers the surface, discoloring it, neither fungus actually eats through the wood, causing decay.