The support structure for any barn truss is the roof truss frame skeleton where the roofing boards and shingles are all attached. Trusses can be built from any kind of material, but are usually made from standard 2x4 boards. Larger barns sometimes have trusses built from 4x4s or even 6x6 timber beams that accommodate the extra weight. Trusses can be designed to allow for greater headroom or provide for a hayloft or other attic-like landing area.
Step 1 – Take Measurements
Carefully measure the barn dimensions so you can calculate your truss needs.
Step 2 - Cut the First Boards
Use a miter saw to cut 67.5-degree angles at both ends of your truss boards, Make sure to face the angles in opposite directions on both ends if you want to install eaves.
Place the two ends together so each cut side intersects at a 22.5-degree angle, which is typical for a standard barn roof.
Step 3 – Brace It
Secure a metal brace across the intersection of the two boards, attaching these with either nails or bolts. Always use bolts when truss timber beams are thicker than 2 inches wide. Repeat the steps above for the other side of the truss.
Step 4 – Form the Roof Shape
Lay the roof trusses together to form a half-octagon shape, and fasten these together with an angle brace. Make sure to leave room for a center support beam, attaching it directly below the roof peak. Use two braces—one for each side—for the roof peak. Since you are using a center peak support, only one metal brace per side is needed.
Step 5 – Cross Braces
After measuring the roof truss width, start from the inside, below the first joint of each side, and cut another board to the length. Make sure the angle of the cut is 22.5-degrees so it will lay flush against the two sides.
Step 6 – Fasten Support
Attach the support boards to both truss sides using a flat metal brace.
Step 7 –Vertical Support
Locate the center of the cross brace and measure from the roof peak to calculate the length of the vertical support beam. Cut the vertical support board to the measured length, paying special attention to the angled cut at the top, allowing it to remain flush against the peak of the roof. Make sure the roof angle is 133 degrees (66.5 times two).
Step 8 – Center Support
Using a metal brace, fasten the center support beam to the roof.
Once you’ve completed construction of your roof truss, make sure all connections are fastened tightly and correctly before completing the roof assembly.
Tips to Remember
Always use proper safety precautions including the use of protective eyewear when cutting wood. Always make sure your work area remains clear to prevent any injuries. Dispose of unused materials in an appropriate manner.