Originally Posted by soparklion11
They burned a 20" wide path through 2x10 and two 2x8s.
That seems very odd. Can you capture a picture of it? Any pipes near it? Any evidence of old electrical? Sweating (soldering) pipes can produce a spot of charring on the joists adjacent to the fitting but it would be unusual for a something 20" long let alone burning through a joist. Too much risk of burning the house down if they were using burning to intentionally cut through a framing member.