When bracing trusses, take time to read and follow the directions from the engineering com- pany. These, along with local building codes, must be followed to guarantee that the house will have a strong and stable roof. Most simple gable-truss roofs are easy to brace.
After four to six trusses have been installed, plumb the gable-end truss and begin bracing the roof. Use a level to plumb the end truss, then install a diagonal 2×4 sway brace from the double top (cap) plate of the exterior wall (where the gable-end truss is installed) to an inboard truss (see the photo on p. 124). The brace should extend at a 45-degree angle from the top plate and be nailed to the top chord (or rafter) or the webbing of an inboard truss.
Securing trusses. An air nailer (top) makes quick work of toenailing the truss’s bottom chord to the wall plate. Drive two nails from one side and one nail from the other. To keep trusses parallel and spaced correctly, nail temporary 1× braces spaced at 24 in. o.c. across the top chords (bottom).
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If the gable-end rafter is plumb, the rafters tied to it at 24 in. o.c. should also be plumb. When all of the trusses have been installed, nail in a sway brace at the other end of the roof. On longer roofs, use additional diagonal sway braces near the center of the house to further strengthen the roof. These are important braces. In a high wind, they will help keep your roof intact.
The next step is to stabilize the joist chords by nailing a long board (a 1× or 2× will do) on top of each joist chord near the center of the span. You can move this bracing to one side or the other if you need to accommodate an opening for attic access, storage space, or room for a heat- ing unit. Frequently a forced air heating unit will be set in this area. Nail this long brace to each chord with two 8d (for 1× stock) or 16d (for 2× stock) nails (see the bottom photo on the facing page). Additional 2×4 braces are often nailed at 45-degree angles across the underside of the raf- ter chords or webbing from the plate line to the ridge (see the top photo on the facing page). Nail these braces into each chord with two 16d nails. This provides lateral stability to the entire roof.
STEP 4 SECURE THE TRUSSES TO THE INTERIOR WALLS
On small houses, trusses are generally engi- neered to obtain their support from exterior walls without needing further support from interior walls. Still, it’s not uncommon for trusses to cross over and bear on interior walls. In most regions, these trusses can usually be nailed directly to the interior wall with two 16d toenails on one side and one on the opposite side. This is not the case, however, if you live in a part of the country where the weather may be freezing one day and boiling the next. In areas with extreme temperature fluctuations, trusses must be able to expand and contract freely. Otherwise, drywall ceilings nailed to these trusses tend to crack. Check with your building department for the code requirements in your town or city. In addition, ask area builders what the local practice is.
5-G Attaching truss clips
Truss joist chord
Leave this nail slightly loose so the truss is free to move up and down.
Double top plate
In areas where large temperature fluctuations are common, fasten the joist chords to interior walls with truss clips so the trusses can expand and contract freely.
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To secure a truss to a wall while still allow- ing it to adapt to fluctuations in temperature and humidity, use a truss clip, as shown in the illustration on the facing page. These clips, which are nailed both to the wall plates and to the truss, feature a slot that allows the truss to move up and down as it expands and contracts— just make sure the nail is slightly loose in the joist chord.
STEP 5 ADD DRYWALL BACKING At this point, you need to add backing (some- times called deadwood) to walls that run paral- lel to the joist chords. The backing provides a nailing base for ceiling drywall (see the illustra- tion on p. 127). It’s easier to put the backing in now rather than after the roof is complete and hampered by sheathing. This is a good place to use knotty, crooked 2× stock. Nail the stock, one 16d nail every 16 in., to the double top plate of parallel walls so that the 2× backing overhangs the double top plate by at least 1 in. on both sides. Some builders use drywall clips instead of solid backing, but I like to fasten nails
Installing permanent brac- ing inside. Shown in the photo on the facing page, a diagonal brace from the top of a truss down to a wall plate helps hold the trusses plumb. Install a 1×6 or 2×4 catwalk on top of the trusses’ bottom, or joist, chord. The brace should be nailed into every joist chord and into the end-wall top plates (photo below). Nail- ing 2× bracing across the webbing provides the roof structure with additional rigidity (photo above). [Photo on the facing page by Don Charles Blom, courtesy Fine Homebuilding magazine © The Taunton Press, Inc.]
TIP
Be aware of overhead issues. If you’re working on the ground while people are working overhead, stay alert while you are in the “drop” zone. Even though workers know not to drop things from above, it’s easy to drop tools and materials accidentally.126 SHELTER
Doing carpentry on the ground is easier than doing carpentry on top of the house. You really have to watch your step.
We handle the trusses carefully.
Plenty of bracing is required to tie the trusses together and to the rest of the house.
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Ceiling drywall can be attached to 2x backing nailed atop a wall's double top plate (see above) or to "ladder" backing, which is created by nailing 2x4s flush with the bottom edge of the trusses' bottom chords over an interior wall.
5-H Nailing drywall backing to interior walls
2x4 backing 2x6 backing
2x6 wall
2x4
wall Drywall nails
"Ladder" backing
Truss clips when needed to allow trusses to expand and contract.
Bottom chord Interior wall
Ceiling joists or joist chords
Screened vent
INSTALLING BACKING FOR DRYWALL
into something solid. (Details on drywall instal- lation are covered in Chapter 9.)
This process is different for trusses that are allowed to expand and contract. In this case, nail fl at 2×4 “ladder” backing between the joist chords on a parallel wall. Use truss clips to at- tach the backing to the double top plate of the wall, as explained on p. 124. This allows the trusses to expand and contract without stressing the drywall.
STEP 6 INSTALL THE BARGE RAFTERS AND THE FASCIA BOARDS As explained earlier in this chapter, barge rafters extend beyond the end of a building, creating an overhang at the gable ends. The rafters are supported by 2×4 lookouts that fi t into notches cut in the gable-end rafters. The lookouts run back to the fi rst inboard rafter (or roof truss). At the bottom corner of the roof,
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a barge rafter meets a gutter or fascia board, which extends along the eave and is fastened to the ends of the rafter tails.
There are a few tricks to making sure that these exterior trim details are done correctly. If you plan to cover the trim with aluminum cladding, as we did on this house (see Chapter 7), the cutting and installation work is a little eas- ier. On the other hand, if the barge rafter and fascia will be exposed as finished trim, you’ll need to cut tight-fitting miter joints where the boards meet. Both types of installation will go more smoothly if you follow the steps described here.