Destructive Timber Decay Caused by Fungi
Puzzle 15 of Building a House Hard Pack
Question is: Destructive Timber Decay Caused by Fungi
and the answer is: DRYROT
Word Meaning:
DRY ROT — The crumbly, decayed portions of wooden members of buildings, especially at or below grade, usually caused by a fungal infection.
Definitions from Wiktionary.