DIY: 2X4 Truss

Trusses are framework structures built from several connected beams. These structures usually formed as triangles because that shape handles stresses well without deforming. Typically, trusses appear in the roofs of buildings because of their sturdy dispersal of pressure and weight. Due to their beam design, 2-by-4 planks make excellent truss building material. While droves of plans for trusses exist, this basic roof truss design uses only 2-by-4 planks and covers a roof width of 24 feet. The same design can be modified using the same principles of construction to fit larger buildings.

Things You'll Need

• Four high quality 14-foot 2-by-4 planks
• Measuring tape
• Hammer
• 20d common nails
• Marker
• Builder's square
• Jigsaw or table saw
• Four clamps
• 1 14-foot 2-by-4 of any quality
• 1 8-foot 2-by-4

Instructions

1. Overlap the ends of two 14-foot 2-by-4 planks by 2 feet. Use two planks of high quality lumber for this part, since it supports a lot of stress. Hammer in 12 20d common nails in two rows to join the planks into one 26-foot beam. Lay this beam out on the ground with the overlap in the center positioned so the left side overlaps the right.

2. Measure 12.4 feet from one end of a high quality 14-foot 2-by-4 use the builder's square and maker to draw a straight line at this point, sectioning off a 12.4 foot length of plank with an extra 1.6 feet on one end.

3. Cut along the line with a jigsaw or table saw. Repeat the same process on another high quality 14-foot plank.

4. Place the two new 12.4-foot planks on the 26-foot base beam in the correct position to form an isosceles triangle from the ends of the 26-foot plank. To do this, take one 12.4-foot plank and place the end of it over the right side end of the 26-foot plank. The overlap between these planks should end at the bottom of the 26-foot beam exactly 1 foot in from the end of the long beam. Do the same for the other 12.4-foot plank, except place the end of it under the 26-foot beam's left end and likewise have the overlap stop on the bottom 1 foot in from the left. In the center of the structure, cross the two shorter planks so the right plank overlaps the left, with 3 feet from the top of the small planks' overlap to the bottom of the long beam directly in its center.

5. Clamp the three beams in those positions tightly, checking all measurements before tightening the clamps.

6. Nail the beams in place with 14 20d common nails in each bottom overlap and four nails in the top overlap. Remove the clamps.

7. Saw off the excess plank in the top ends of the 12.4-foot planks to make a clean triangular top. Also saw off the extending ends of the 26-foot beam, but leave the bottom ends of the 12.4-foot planks alone.

8. Measure 7 feet from the end of the 14-foot 2-by-4 plank and draw a line dividing the plank in half.

9. Saw along this line to extract two 7-foot long 2-by-4 planks.

10. Position the 7-foot planks on the triangle structure in the correct locations. One end of the first 7-foot plank sits on top of the left 12.4-foot beam butted up against the end of the right 12.4-foot beam. Have the top of the lower end of the 7-foot beam cross with the 26-foot base beam 4 feet to the right from the center of the base beam, overlapping the 26-foot plank. The second 7-foot beam follows the same measurements and placement, except the top end lies under the right 12.4-foot beam butting up against the end of the left 12.4-foot beam, then the second 7-foot piece goes left to cross under the 26-foot plank with the top crossing over 4 feet from the center.

11. Clamp the 7-foot beams in place, checking measurements.

12. Nail the 7-foot planks in place with three nails in each other overlaps, the two overlaps on top with the 12.4-beams, the overlap near the top between the 7-foot planks, and the two bottom overlaps with the base beam. Remove the clamps.

13. Saw off the excess triangles of wood on the ends of the 7-foot planks so they are flush with the triangular truss structure at large.

14. Mark cuts on a 8-foot plank of 2-by-4 lumber, first 39 inches from the end and then 39 inches from the first mark. Saw along these marks.

15. Place one end of one of these beams, the shortest beams in the structure, underneath the right 12.4-foot beam so the point at which they cross on the right hand side of the short beam and top of the 12.4-foot beam directly above a point 6 feet towards the center of the 26-foot plank from the right end of that base beam. Mark this location for this end of the shortest beam by tracing it onto the 12.4-foot beam. Notice that the lower end of the shortest beam wants to sit on top of the base beam, not overlapping it. Draw an angled line on the shortest beam with the builder's square so you can cut the end to sit flush on the base beam with the top end in the predetermined location. Cut this angle with a saw, and clamp this shortest beam in place.

16. Repeat the process for the other 39-inch beam except as a reflection on the left hand side, with the top end of the shortest beam overlapping the left 12.4-foot beam.

17. Nail the shortest beams in place with four nails in each top overlap, three nails in each overlap with the 7-foot beams, and one nail on each bottom of the shortest beams, nailing them to the base beam from the top.

References

• Louisiana State University Ag Center: 24-Foot Lap-Nailed Truss
• Roof 101: DIY Roof Truss Construction