Hello Mat,welcome to houzz and we hope to see you again after your project is complete. It is helpful to know if our advice was good,bad or caused more problems than solved. First off,recip saws are only one in a diy handyman's arsenal of saws and imo least suitable for what you are doing. If dam is nailed to side of joist/truss,a much safer choice would be a Wonder Bar,aka flat bar and pry bar. Place bar at crack between dam and joist,tap hard with hammer while wiggling bar until bar is 1" into crack then pry hard on bar. Work your way back and forth along crack until dam is seperating from joist. At that point push on top of dam with one hand as you continue prying with other hand. That should remove the section of dam. Remember,tell us how it worked. If you mashed a finger or poked an eye out we won't give that same advice again.

Hi Klem- Thank you for the welcome and advice. My initial thought was just to cut along the Truss/Joint and not worry about the inch or so of wood that was nailed to the Truss. The Wonder Bar and Pry Bar idea sound very good also...might look into those instead. Will definitely keep you updated. - Thanks again!

You are welcome Matt. My reasoning for prying it off is mostly because of the difficulty in cutting straight and level with truss so that new floor properly rest's on truss. My experienced helper recently used sawzall for window cut outs and had to clean up with Roto-Zip before getting clean edges. His body was better positioned for that chore than it would be here and saw still wandered. Recp saws are great in some situations but are difficult to follow straight lines with.

Hey Klem - The prybar worked well - especially once I figured out it would work better to get into the angle formed by the dam and truss from behind the dam instead of the front... lol. And no mash fingers or poked eyes...or holes in the ceiling....

Way to go Matt, holes in ceilings are allowed,the best of us make one from time to time. Your union card is waiting at the front desk. (: