Wood trusses are made from wood, steel or a combination of both materials. They are designed to support a roof and distribute the weight of the roof evenly. Wood trusses are used in homes, commercial buildings and industrial structures.
Wood trusses are built using engineered plans that include drawings and specifications for the exact dimensions, materials and components needed to ensure proper fit and function. The plans may also include information on how to build the trusses, including cutting lists and measurements for each component.
The wood truss shown above has the following specifications:
The quality of the sawn lumber used in this project was #2 spruce.
This wood truss is suitable for a span of 14 feet.
The height from the bottom of the top chord to the bottom of the bottom chord should be about 1/3rd to 2/5ths of the span, or about 4′ – 9″ in this example.
Use 3-1/2″ x 1-1/2″ galvanized nails spaced at 6 inches along each edge and 4-1/2 inches at each intersection.
If you are going to install metal roofing, use 12 gauge (0.105″) screws rather than nails. Space them 6 inches apart both horizontally and vertically and use #10 common washers under the head. If you are using a thicker steel panel (.0185″) space them closer together, say 4-1/2″.
Section: Truss Design
Section: Materials Required For Making A Wood Truss Of This Type
Section: Cutting The Lumber To Make A Wood Truss Of This Type
Section: Nailing Together A Wood Truss Of This Type
Takeaway: This article has described all important steps for building a wood truss that is suitable for spans up to about 20 feet when #2 spruce or other common structural lumber species are used for its construction. By adjusting some dimensions and by using stronger lumber such as Douglas Fir, this design can be modified to fit any situation where only wood trusses will do!
1. Check the truss design for local building codes.
You’ll need to check the truss design for local building codes.
Some areas require that you use a registered engineer or structural engineer. You can use an online roof truss calculator to determine if your design is structurally sound, but you may still need to hire an engineer if you are building a single-family house or multi-family home (or any other structure that requires more than one load-bearing wall).
2. Cut a 2-by-4 to length to serve as the bottom chord of the truss.
- Use a miter saw to cut the 2-by-4 into two pieces that are each 12 feet long.
- Nail one piece of wood to either end of the sawhorses (or use another method of securing it). It should be flush with the top edge of your sawhorses, parallel with them, and about 6 inches away from them on its own side.
- Measure down along this bottom chord, using a tape measure or level as needed until you reach a point where it is 4 feet above the ground when measured from your floor joists (the floor supports that hold up walls). This is where you will place your trusses later on; if they are higher than this height then they must be adjusted accordingly before being placed on top of these bottom chords so as not to interfere with nearby trim work or other elements in your project
3. Cut another 2-by-4 to length to serve as the inside top chord of the truss.
3Cut another 2-by-4 to length to serve as the inside top chord of the truss.
Mark your board at 24″ long and cut it down with a circular saw or handsaw. This will be your top chord, so make sure you cut it as straight as possible by using a clamp and level or measuring tape. The two pieces should be identical in length, width and thickness (2″) if possible!
4. Lay the bottom cord flat on a pair of sawhorses.
4Lay the bottom cord flat on a pair of sawhorses. Make sure the chord is perfectly flat, straight, level and square. The top of your truss should be facing up at this point.
5Place one end of an I-beam or 2×4 under each arm of your truss so that they straddle the chord you just set on your sawhorses and are facing upward toward the peak of your truss.
5. Lay one triangle face down on a pair of sawhorses so that it straddles the bottom chord. Make sure that the peak is facing away from you, toward the ceiling of the structure.
5Lay one triangle face down on a pair of sawhorses so that it straddles the bottom chord. Make sure that the peak is facing away from you, toward the ceiling of the structure.
6Measure and mark each end of both sides with a pencil. 7With your speed square, mark lines at 45° angles along each side where they meet at their ends at X-brace locations 8Measure and mark each end of both sides with a pencil. 9With your speed square, mark lines at 45° angles along each side where they meet at their ends at X-brace locations 10Repeat steps 6 through 9 for all remaining trusses 11Tape two pieces together to form an L shape 12Mark lines across both halves of these pieces 13You should now have 4 identical L shaped pieces 14Secure these pieces together by screwing them into place with 3 inch screws 15Place one half flat on top of another half so that you have one whole piece 16Use two 1/2″ nails to secure them together 17Flip over your complete L shaped truss 18You should now have 2 identical L shaped trusses
6. Place a nail or two into either side of each joint between the chords and braces. Use power tools to secure each nail head below the surface of each piece of wood, using caution while working with such tools.
Nail heads should be below the surface of each piece of wood, but not so far down that they cannot be seen. Use caution when using power tools to secure nails into place.
If you are not comfortable with using power tools in this way, do not use them to secure nail heads until you have gained confidence in your ability to work safely with these tools.
7. Place another nail through each joint at an angle so that it will stick out at right angles to both sides of each joint. Bend these nails over with a hammer to lock them in place, or secure them with power tools.
Nail the joints together by placing a nail through each joint at an angle so that it will stick out at right angles to both sides of each joint. Bend these nails over with a hammer to lock them in place, or secure them with power tools.
Use caution when nailing wood trusses together. You may want to use a ladder and safety glasses while doing this work, especially if you are using power tools such as nail guns or electric drills that require extra care in handling due to possible injury from flying bits of wood or metal objects being ejected by the tool itself when used improperly.
8. Repeat Steps 5 through 7 for other trusses, positioning them at equal intervals across your roof span. Consider consulting with a professional contractor before attempting this project if you have any doubt about your ability to assemble accurate trusses.
Repeat Steps 5 through 7 for other trusses, positioning them at equal intervals across your roof span. Consider consulting with a professional contractor before attempting this project if you have any doubt about your ability to assemble accurate trusses.
Place another nail through each joint at an angle so that it will stick out at right angles to both sides of each joint. Secure each nail head below the surface of each piece of wood so it cannot be seen from the outside once your trusses are installed on the roof.
How To Build Wood Trusses
1- Check the truss design for local building codes. Trusses that span more than 20 feet require a permit in all but three states, so it’s important to check before you begin construction. The size of your truss will dictate how long it takes to construct; smaller structures can be built faster than larger ones.
2- Cut a 2-by-4 to length to serve as the bottom chord of the truss. Measure down from each end of the board and make marks indicating where you want the peaks of your triangles to fall (the peak is where two sides meet). Then measure up from both ends of that line and mark where you want your top chord (the horizontal beam) and bottom chord (the bottom half of each triangle) measurements should fall on this one piece of lumber.
3- Cut another 2-by-4 to length to serve as the inside top chord of the truss. Make sure this board is about 3 inches longer than its partner on either side, if possible; otherwise, it may not fit snugly into place when installed later on.
We hope that this article helped to show you how easy it is to build wood trusses. As you can see, there are many different ways in which these structures can be built but the most important thing about building your own is knowing that they will not only last for years but save you money as well.