How to Assemble Scissor Trusses

Measure the area of the home which is designed with a vaulted ceiling on the blueprint sets. Identify the width of the house, size of the room, slope of the roof, the size of the soffit, height of the vaulted ceiling and number of trusses needed to span the room in question. All of this information is written on the blueprint set.

Draw a scale profile drawing of the truss on paper in 1/4-inch scale using the architect's scale. Draw the entire truss to scale, including all of the upper and lower cords and truss webbing.

Consult a local architect or general contractor to get the specific design parameters for your trusses. Depending on the distances the trusses span, the load, design of the home, etc., the size and layout of the truss members will vary. Each truss must be engineered specifically for your building application. The differences between trusses involve how many diagonal web braces, placement of the web braces within the truss and the size (lumber dimension) of the upper and lower cords, which can be 2-by-4's or 2-by-6's. These details must be verified by building and construction professionals.

After the truss is accurately drawn on paper, measure the lengths of the individual pieces of lumber, and identify the angles required for each joint. Cut out the pieces of the truss from the appropriate size dimension lumber.

Lay out the truss pieces on a hard, flat, open area, such as a concrete slab, in the proper configuration. The slab must be flat, level and hard.

Place a truss plate on each joint. Using the hammer and the metal plate, hammer the truss plate into the wood to secure the joint. Make sure that the wood pieces butt together at each joint and that no space remains between the pieces of lumber.

Flip the truss over and install truss plates on the reverse side of the truss. The structural pieces of lumber that make up the truss must be fastened on both sides in order to create a strong truss.