Lumber trees are what you use to make lumber and timber.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Why are you mopping that wood with a Quickle wiper?
I heard that if you go to the lumber yard at 8 p.m. you'll be able to meet God.
We should get started building the doghouse as soon as the lumber gets here.