How to Set Large Barn Trusses

Cut several 22.5-inch blocks from your 2 by 4 lumber. The number will depend on the amount of trusses to be set; 2 blocks per truss, one for each side. For example, if you have 20 trusses to set, multiply that number by 2 and you get 40 blocks. Subtract the two end trusses, which will not require blocks, and you have 36 22.5-inch blocks for your truss spacing. These blocks will help you quickly place and space your trusses, but are not replacements for layout marks.

Layout the top plate of the barn walls by measuring off of one end of the barn wall 24 inches and marking it will an X. This is your center mark for your truss placement. However, subtract 3/4-inch from this mark for a mark that represents the edge of your truss since you cannot see the center mark once the truss has been set. For example, 23 1/4-inch, 47 1/4-inch and so on. You will still place an X at the 24-inch centers along with the edge mark for your truss.

Connect a towing strap to the first truss and have a crane lift the truss onto the top of the barn wall. Set the first truss on the end of the wall and attach the truss at the wall plate where the truss rests using a hurricane tie on each end of the truss. Have a helper hold the truss in place.

Place two 22.5-inch blocks between the first truss and the next. Pay attention to the layout marks. Set the next truss in place, and attach the truss to the barn wall plates using hurricane ties. Attach 8 foot 2 by 4's on the top of the two trusses using 16 penny nails, one 2 by 4 on each side of the gable. Allow the 2 by 4's to extend past the trusses in the direction of the installation. Once the two trusses are tied together, they will stand alone. Continue to add trusses with blocks in between as spacers. Add more 2 by 4's on top of the trusses, tying the truss system together temporarily.