Extending Roof Line . Start conventional overhangs by taking off the existing fascia and any other trim that covers the rafter tails. Some of the most common materials for roof extensions are: extend roof line, verandah Bingie Builders from bingiebuilders.com.au This option works best when adding space along the side wall from your main home. If i pull the lower roof plane away so that it is no longer up against the exterior wall of the upper roof plane, the line goes away. Once i pull the lower roof plane back against the outer surface of the exterior wall, the line reappears.