Also called “soft rot“, this fungus is known to break wet wood down into cellulose, which will significantly weaken and decompose the material.
When choosing between replacing and reinforcing joists that have been damaged, look carefully at the color of the wood.
Advanced damage will show up as darkening and shrinking of the wood. It will have a soggy, spongy appearance, and will show signs of prolonged moisture exposure.
Often, replacement of this wood will not be necessary. Instead, installing a sister beam and sturdy joist supports may be more than enough to address all present damage, and restore your structure to a stable condition.