But you have to do it before you build the walls.
How to attach the shed roof to the walls.
Then nail that piece down.
This will occur at all four corners adding an additional attachment point for each corner.
The best method is to snap chalk lines on the shed floor to outline the truss parts.
The most common roof to wall intersections involve either a gable roof with its ridge running perpendicular to the wall or a shed roof that slopes downward away from the wall.
The top plate on each side will overlap and attach to one adjoining wall corner.
Cover the walls with board and batten 4 by 8 foot sheets of plywood nailed vertically to the sheathing strips with the seams covered by 1 by 4 inch batten boards.
Experiment with jacking different corners or walls until you get the results you want.
Lower the first rafter truss into place at either the front or back of the shed.
The positioning of your rafters will depend on the pitch of the porch roof.
Add a second top plate to more securely attach the walls and to add strength and support for the roof.
Rafters are installed piece by piece during the construction of the roof.
After that to make it flush with the roof of the existing house cut the two outer rafters.
Rafters are beams that run from the peak of the roof to the top plate of the supporting walls.
Make a cutting on one of the sides of the horizontal roof beam on an angle.
Put a jack under a corner and raise it up till the roof sheeting comes in line with the truss.
They join at the peak of the roof by connecting to the opposing rafter or to a ridge beam that runs the length of the peak of the house or shed.
Use 3 nails for each side.
After the roof is sheeted then go around and re level the floor.
Do the same with the rest of the pieces.
The porch roof may match the pitch of your home or have a more shallow roof pitch.
Joist hangers can help you mount each rafter to the house.
Use screws to secure the rafter to the sill plate.
Then use the chalk lines as a guide for cutting the truss patterns and assembling the trusses.
Seal the top with clear caulk.
Attach the horizontal beam by using a nail gun.
You have to do it thoroughly so that the rafters sit flush on it.
Fasten the truss by driving 8d finishing nails at an angle down through the board just above the birdsmouth notch and into the underlying wall plate.
If you re building your own roof trusses the handiest place to assemble them is right on the shed floor.