Retrofitted Shed Dormer


I own and live in the middle unit of a one-story tri-plex that has a truss-framed roof. The interior has high ceilings that would potentially allow the addition of a second floor room. I am contemplating adding a shed dormer to create a second story bedroom. Do you have any suggestions as to how a shed dormer could be added? I am familiar with how to frame up a shed dormer if the original framing were rafters and a ridge board, but the truss construction has thrown me for a loop.


It is difficult to give you a definitive answer on your project, but we can offer this information:

  • Trusses can be modified after installation, but it will require having a design professional involved in the retrofit. Any change to the truss means it will have to be re-engineered and strengthened so that it can maintain its original load capacity.
  • A good place to start is with the original manufacturer of the trusses. Do you have access to the attic space so you can check if the manufacturer's contact information is stamped on the truss?

Ideally you should have the original truss design drawings and specific plans for your project to take to a local truss manufacturer (see our Members Section for truss manufacturer listings) or to a design professional experienced with metal plate connected wood trusses.

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