Trusses form the roof line on buildings and provide support for the lumber that holds shingles or other form of roof cover. Without bracing, it is almost impossible to install trusses. Some bracing provides a way to put up the trusses evenly, while holding them and other bracing supports them after they are put up.
Bracing for Putting up Trusses
As each truss is put up on top of opposite walls, it must be put up straight and supported while the next truss is put up. Usually, trusses are put 24 inches apart. To hold them up until the decking of the roof is placed on top, a 12-foot-1-inch-by-4-inch piece of lumber is used. It can be nailed temporarily to each truss as the next truss is put in place. When all the trusses are installed and the first row of decking is on, this brace is removed.
Bracing for Extra Support
Pieces of 2-by-4-inch lumber are placed between the trusses underneath the decking to keep trusses straight. If the attic is being finished for living space, these pieces, called scabs, can be installed flush with the trusses to provide areas for sheetrock or paneling to be nailed to. Extra support for the trusses can be made by placing a 2-by-4-inch piece of lumber from each truss on one side to the truss on the other side, high enough to provide head room but low enough to provide support for the trusses. In this situation, the walls of a finished attic space or room would go with the roof line.
In addition, two types of braces can be used in an attic to provide extra support for the trusses, if needed. One kind is used if you are going to finish the attic to provide living space. The other is just used to support the trusses. A great deal depends on the pitch of the roof. A higher-pitched roof would be better for extra living space than a lower-pitched roof. Once again, a 2-by-4-inch piece of lumber is placed between the trusses and parallel to the ceiling joists. This is where a high-pitched roof is necessary. This brace needs to be far enough up the trusses to provide headroom and still provide support for the trusses. 2-by-4-inch pieces of lumber are attached from each end of this brace, to each ceiling joist, perpendicular to the ceiling joist, forming a wall, and supporting each truss. In this situation, the walls are like that of a room and the roof line is behind them.
In the situation where the attic is not being using for living space or where the pitch of the roof is too low, 2-by-4-inch pieces of lumber are used as braces and are placed from the middle of each truss to the middle of each ceiling joist. These braces need to be flush with the ceiling joists to allow for installing sheetrock on the ceiling of the house.