Neighbor was cutting his trees down and one BIG section of his poplar fell on the center of our house. We have an older home and the rafters are on 24" centers. The tree fell parallel with the rafters. The rafter that it hit had two large knots. The rafters are 2x6 by 16'. The largest knot was pretty much centered and it broke out leaving a large horizontal centered crack that extends both directions approximately 4 foot each way. Question is how do we best fix this? Do we put a scab on both sides the full length and how much past the end of each crack? Also should we put in upright supports at the end of each scab? What material should the scab be?