A roof dormer is much more than just a beautiful accent to your home. There is also a function to roof dormers that make them appealing to home owners. Roof dormers can be an inexpensive way to add more head room to your upper floor without having to build an entire second floor or raising the roof. Adding a roof dormer to your existing structure will add to the overall value of your home, and can be done with some basic tools and experience.
Take Measurements and Locate
Begin by locating where you want the roof dormer to be installed. This is usually at a current window, but does not have to be. Take measurements and begin to remove the roofing materials so you can see the nail heads of the sheathing.
Start Building Dormer
Beginning with the front wall, start framing with 2x4 standard framing techniques. You will have to angle the 2x4's at the bottom to compensate for the roof slope. Using your roofing square you can quickly determine the angle for your cuts. Using your skill saw, or a mitre saw, make the cuts and begin framing in the dormer. Take great care with the front wall. This is going to be the measuring point for the other two wall so it must be level and straight.
Frame in Window and Header
While framing in the front dormer wall, frame in the window with a header board at the top. Make sure the opening is level and that it is straight.
Install Top Plate and Side Walls
Place a top plate from the roof to the top of the front wall and then begin framing in the side walls. Pay attention to beveling the bottom of the frame to compensate for the roof's slope. Place roofing felt and metal flashing to the bottom of the frame and nail to the roof
Dormer Roof Rafters
Connect the top plate to the side walls with rafters. Using your skill saw and roofing square, cut the 2x6 rafters and nail in place.
Wall Sheathing and Wrap
Nail the 3/4 inch plywood sheathing to the frame and roof, and wrap in home wrap. Finish off the dormer roof with roofing felt and matching shingles to the rest of the house.
Cut Out Roof Section
Using a reciprocating saw, carefully cut out the roof section that will open the dormer to the rest of the room.
Finish off Inside Walls
Install insulation and vapor barrier to the walls and then drywall. Apply the drywall mud and tape over seams and screw holes and sand smooth. Once clean of any dust, paint the walls your desired color.
Side the Outside Walls
Once all is finished inside, then you can finish off you new roof dormer by adding the vinyl siding to the outside walls.