How To Overbuild A Roof That Is Too Old To Carry A New Load. On a recent project, we added a large master bedroom and bath addition to a 1940's Beaverton bungalow. As in many additions, the roof presented the particular problem of not making the addition look like a tack on. The solution was a raised roof over the entire structure including the new addition. In order to not to have to remove all the existing roof, because it would not carry the new roof load a cantilever truss was designed, allowing no load to be put on the existing roof structure. The existing roof, as so many of the time period, used 2x4 members, which would never carry even the existing load under todays codes. Email for more information.