How to Tie in a Roof Addition

Many houses are expanded over time, as more children arrive or circumstances change. An addition may be as as complex as a whole new wing. Most additions, however, are pretty basic: a carport, a garage or a new bedroom or a playroom. Whatever the addition, however, it will have a roof that will have to be connected with the roof on the existing house. Connecting two complex roofs, like hip or gambrel styles, may require professional engineering and construction. A basic addition with a shed or single slope roof, a basic style, while still challenging, may be within the abilities and ambitions of a layperson.

Pry bar
2-by-6-inch ledger board
Tape measure
Chalk line
Nails
Hammer
Power drill
Lag bolts
Ratchet wrench and socket
Rafter or joist hangers

Instructions

- 1
  Install a ledger board, which will serve as a connection point for the new roof, on the old roof. Locate the ledger so it will provide sufficient slope for the addition roof, ideally at least 4 inches per foot from the house to the end of the new roof. Remove the shingles from the old roof along that area, pulling the nails with a pry bar. Try to preserve the shingles and remove them without damaging them so they can be reinstalled.
- 2
  Cut a 2-by-6-inch board as long as the addition roof is wide, allowing for side bands and any edge overhang on the new roof. Mark both ends where the roofs will meet and snap a level chalk line for the bottom of the ledger board. Find rafters or truss chords in the old roof to tie into. Get in the attic and look for appropriate structural members, then drive a nail through the roof sheathing to mark those spots.
- 3
  Nail the ledger board temporarily along the level line with a hammer and framing nails. Mark all rafter or truss locations on the ledger and drill pilot holes through the ledger into the structural members of the old roof. Fasten the ledger to the roof with lag bolts. These should be long enough to penetrate through the ledger, the sheathing and at least 1 1/2 inches into the truss or rafter. Fasten bolts with a ratchet wrench and socket.
- 4
  Attach metal hangers that fasten to the ledger board and have brackets to hold connecting elements of the addition roof. Use rafter hangers if individual rafters will run from the ledger to the end of the new roof. Use joist hangers, which are similar but hold larger boards, to attach joists for the length of the roof with rafters perpendicular to the joists.

How to Enclose an Open Porch With a Roof

Basement Backfill Options

Exterior Remodeling