Framing A Shed Dormer Roof

Shed dormers are an efficient way to gain more space.

Framing a shed dormer roof.

Be extremely careful not to damage the existing structure. To correct a slight dip in the floor we established a benchmark height with a laser level and nailed 2x6 squash blocks to the sides of the existing floor joists. Along the level line and using a square to draw a perpendicular line up to the roof edge of the board. Building a 20 ft wide shed dormer doesn t take much more effort than building a 4 ft wide version.

However the width can be increased with properly sized and engineered support framing. This framing option is usually best for dormers up to 6 ft. Because they can be much wider than gable dormers shed dormers can provide more headroom and therefore more usable space. Roof framing doesn t have to be daunting but if it s your first try a simple gable roof say on a garden shed is the best bet.

Cut the shed dormers opening with a reciprocating saw. Purchase your materials including wood windows and any other specialty. Wide depending on the size and length of the existing rafters. The end wall of a shed dormer carries the load rather than the sidewalls.

The roofing material will need to be stripped back for this step. Finish the end walls with blocking studs notched to fit around the rafters and fastened to the top plate. If the slope of your dormer roof is the same as your old roof hold a scrap of plywood against the old roof boards and draw a level line on it. Create a layout that incorporates the details of the project such as slope headroom and exterior appearance.

Make a rafter cutting jig by measuring 12 in. Schedule your project considering that the roof will be wide open and the work may last an entire day. They also give you more bang for the buck. The shed roof rafters are fastened to the other side of the header.

After the walls ridge and common rafters are set i overlay the valley framing on top of the main roof sheathing to save from cutting a true valley. Remove the temporary collar ties. Usually a dormer is made for extra light into a house. On the roof using the pilot holes drilled in step 1 snap the lines that will denote the opening in the roof for the dormer.

Framing a shed dormer is a simpler process than building a gable dormer.