From 
Image 1 of 15
1. Remove the shingles from the area of the new dormer. Snap chalk lines for the inside edge of the dormer side walls, set your saw to cut through the roof sheathing and saw from bottom to top on both sides. Leave the overhang sheathing uncut. Pry off the old sheathing boards.
Image 2 of 15
2. Using dimensions from your plan, draw lines on the floor to indicate the location of the front dormer wall. Plumb up from the outside face of the wall line and mark the rafters. Deduct an additional 1-1/2 in. to allow space for the new header (Photo 4) and cut off the rafters with a circular saw.
Image 3 of 15
3. Cut the new triple rafters to the same length and angles as the old and slide them under the roof sheathing. Nail through the ridge board into the ends with three 16d common nails. Nail them together with pairs of 16d nails every 16 in. Toenail the bottoms to the plate with two 16d nails, then add a metal strap.
Image 4 of 15
4. Install the lower header with joist hangers (Figure A) and assemble the front wall on the attic floor. Stand the front wall and align it with the marks on the floor. Shim under the bottom plate to level it if necessary, then nail it into the floor joists with 16d nails. Plumb the corners with a level and brace them with 2x4s.
Image 5 of 15
5. Add a corner stud, then cut the roof slope angle on the end of a 2x4 to use for the top plate of the side wall. Put the plate in position, level it and mark its length. Cut it and nail it to the corner stud and roof, making sure it remains level.
Image 6 of 15
6. Fit and install the bottom plate. Then measure, cut and nail in the wall studs every 16 in. with two 16d nails at the top and bottom. Make sure they’re plumb. Add a second top plate, overlapping the corners (Photo 7).
Image 7 of 15
7. Cut a 2x4 to temporarily support the new 2x8 ridge at its correct height (see Figure B). Hold the ridge board level and mark the side rafters at the top of the ridge board. Cut a 2x8 header to fit across the opening and attach it to the new rafters at that height with metal joist hangers.
Image 8 of 15
8. Cut the ridge board to length and notch it according to your soffit details. Then nail it to the center of the header, using a metal joist hanger for extra strength. Cut and install the common rafters spaced 24 in. on center (Figures B and C).
Image 9 of 15
9. Stretch a string across the top of the rafters, aligned with the inside of the side wall, and make a mark where this line intersects the top of the side rafters. Now measure from this point up to the intersection of the ridge board and header to find the length of the valley rafters. Cut them according to Figure C.
Image 10 of 15
10. Nail up both valley rafters. Use a straightedge to make sure they’re aligned with the tops of the common rafters. Then measure, cut and nail the valley jack rafters every 24 in. on center. Cut valley jack rafters to the same angle as the common rafters, but bevel the bottom cut 45 degrees.
Image 11 of 15
11. Add the subfascia and 2x4 overhangs (Figure A). Sheathe the walls and roof with plywood. Drive 8d nails every 6 in. along the edges of the sheathing and every 8 in. along all other studs. Complete the soffit and overhang details according to the plan (Figure A).
Image 12 of 15
12. Fit the roof trim and nail it on (Figure A). Complete the underside of the overhang and soffits and add a roof edge molding to match your house. Install step flashing and reroof along the dormer edges.
Image 13 of 15
13. Cover the valley and roof edges with a 36-in. wide strip of ice-and-water barrier. Then install a preformed galvanized metal valley (or use other methods approved by your building inspector). Shingle the roof from the bottom up according to the instructions on the shingle packaging.
Image 14 of 15
14. Flash and install the windows. Then staple No. 30 building paper to the sides, lapping top sheets over bottom sheets. Nail the corner boards into place and add the siding. Prime and paint.
Image 15 of 15
15.Nail up the rafter ties, making sure to keep them level and aligned with each other. Add blocking and furring strips as needed to bring all of the interior framing to the same level, ready for drywall.
Copyright ©2005 Home Service Publications, Inc.
Comments :