Figure 8.1, Roof framing detail
- Gable end trusses
- Regular trusses and loft floor
- Truss end board
- Flying rafters
- Flying trusses
- Eave boards
- Roof sheeting
You can either mark the top plates at 16 inch O.C. or use the wall studs below each truss as a reference.
Attach a 2×4 brace
Attach a 2×4 near the center of each end wall that extends 3 or 4 feet above the top plate.
This will serve as a stop and a brace once the gable end is raised into place.
Install a spacer made from 2 layers of OSB between the wall and the brace. This 1 inch gap will allow the gable end siding overhang to slide in where it will overlap the end wall siding at the top plate.
Attach gable end trusses
For large sheds this is a 3 person job because the ends are heavy and you will be working up on ladders.
Set a ladder at the outside of both corners of the end wall.
Carry a gable end in and set it on the top plate upside down and backwards near the end wall.
Raise it up horizontally and hold it in place with a 2×4 resting on the floor in the center of the base piece and one at the top center of the truss. Be careful to adequately support the center of the truss when it is horizontal because it’s heavy and might break under it’s own weight as it has little strength in the horizontal direction.
Get your helpers up on the ladders and use the 2×4 in the center of the top of the truss to raise it up vertical. Then the helpers on the ladders can move it in place to sit it on the end top plate.
The 2 inch siding overhang will slid in the gap between the wall and brace. This is why you need to space the braces 1 inch from the wall.
Secure the truss to the end wall with nails or screws. You might also want to secure it to the vertical brace with a temporary screw for larger and taller trusses.
Repeat this procedure for other end wall.
String line
Attach a string line between one of the ends of both gable end truss and pull it tight.
This is a reference line to verify that each truss is properly centered before you permenantly secure it in place.
Stack trusses
Since the trusses are taller than their O.C. spacing you need to stack some of them on one end of the shed. Otherwise you will not have the space to raise the last few.
Carry each truss in and sit it on the wall upside down near the end. Raise it upright and slide it to rest against gable end truss and secure it in place with a strap.
Do this for at least half of the trusses, depending on the length, width and pitch you are building.
Install trusses
Position the truss on the top plates at 16 inch centers and verify that the end it is in line with the string line and that the end of the truss base sits at the outside edge of the top plate. Not at the outside edge of the siding.
This is to make sure the walls have not spread to more or less than dimension “A”. Then attach the truss with two 3 inch drywall screws toe nailed into each top plate.
If the siding is keeping the truss from sitting down on the top plate then move the truss to one side. Take a hammer and break the corner of the siding down until the truss sits tightly in place.
If you can’t get all 3 points of the truss in their proper position this might mean the walls are bowed or spread. You can correct this with a temporary 2×4 brace between the offending part of the wall and the floor.
Screw it into the floor and a near by wall stud if necessary.
Loft floor ?
If you’re going to make a loft you need to move the 4×8 plywood floor pieces into place before the last 8ft of trusses are installed.
Otherwise you will not have access to get a sheets of plywood in.
Stack all the floor pieces in the first 8ft of trusses then move them into place after the rest of the trusses are installed.
See Figure 8.1, Roof framing details
Truss end boards
Determine how much overhang you want on the gable ends and cut the truss end board accordingly.
Attach them to the truss ends entended out beyond the gable ends. These boards will be the full dimension of the gable overhang.
Flying rafters
Cut the flying rafters 1 1/2 inches less than the truss end board overhang to allow for the width of the flying truss and install them with nails or screws.
Flying trusses
Raise the flying truss into place and attach them to the truss end boards and flying rafters.
Eave boards
Cut the eave boards from siding about 8 inches tall and fit them in between each truss and in line with the top of the trusses.
Attach with several galvanized nails into the top plates.
Ventilation
If you want to add some ventilation you can drill several 2 or 3 inch holes into each board and cover it with screen stapled in place. This will provide extra airflow if you later install a turbine vent.
Sheet the roof
Install the roof sheeting and nail in place with 8d nails every 8 inches. Stagger the joints for maximun strength.
Once the sheeting is in place snap chalk lines and nail the field every 8 inches.
Remove flying truss braces
Once the flying trusses are securely nailed to the sheeting you can remove their temporary braces.