Pressure Treated Lumber

PT lumber is heavier at the store (water content from treatment) but upon drying they go back to just about their normal weight. Wet wood is 78% heavier than un-treated - so there is a significant difference in weight for treated vs not under typical conditions.

https://roofonline.com/weight-of-pressure-treated-lumber/#:~:text=Weight%20of%20Preservative%20in%20Pressure%2DTreated%20Lumber&text=For%20much%20of%20the%20pressure,0.37%25%20more%20than%20untreated%20wood.