Trusses are often used in building construction to create strong and lightweight structures. They are particularly well-suited for roofs, bridges, and other applications where long spans are required. Trusses can be made from a variety of materials, including wood, metal, and composites. In this article, we will focus on how to make a wooden truss. **Building a truss is a complex process that requires careful planning and execution. However, with the right tools and materials, it is a project that can be completed by do-it-yourselfers.**
The first step in building a truss is to design the truss. This involves determining the span of the truss, the load that it will be required to support, and the materials that will be used. Once the design is complete, the next step is to gather the necessary materials. These materials include lumber, nails, screws, and glue. It is important to use high-quality materials to ensure that the truss is strong and durable.
The next step is to cut the lumber to the correct length. This can be done using a saw or a miter saw. Once the lumber is cut, it is time to assemble the truss. The first step is to assemble the top and bottom chords of the truss. The top chord is the horizontal member that runs along the top of the truss, and the bottom chord is the horizontal member that runs along the bottom of the truss. The top and bottom chords are connected using vertical members called webs. The webs are typically spaced evenly along the length of the truss. **Once the truss is assembled, it is important to check that it is square and that all of the joints are tight.**
Identifying Truss Types
Truss Terminology
A truss is a structural framework that is assembled from individual members, typically made of wood or steel. These members are connected at their ends to form triangular units called “panels.” The panels are arranged in a specific pattern to create a strong and efficient structure.
Top Chord
The top chord is the upper horizontal member of a truss. It is responsible for carrying the loads from the roof or other elements above the truss to the supports at the ends of the truss.
Bottom Chord
The bottom chord is the lower horizontal member of a truss. It is responsible for carrying the loads from the supports at the ends of the truss to the walls or other elements below the truss.
Web Members
The web members are the diagonal and/or vertical members that connect the top and bottom chords. They are responsible for transferring the loads from the top chord to the bottom chord and vice versa.
| Truss Type | Description |
|---|---|
| King Post Truss | A simple truss with a single vertical web member in the center of the truss. |
| Queen Post Truss | A truss with two vertical web members that are located at the quarter points of the truss. |
| Scissor Truss | A truss with a V-shaped top chord and a horizontal bottom chord. |
| Pratt Truss | A truss with diagonal web members that form a series of X-shapes. |
| Howe Truss | A truss with diagonal web members that form a series of V-shapes. |
Gathering Essential Materials
1. Identify the Desired Truss Type
The first step in making a truss is to determine the specific type of truss you require. Trusses come in various shapes and sizes, each designed for different roof loads and spans. Common truss types include king post, queen post, and Fink trusses. Consult a structural engineer or building code to determine the appropriate truss type for your project.
2. Acquire Suitable Lumber
The backbone of a truss is the lumber. Typically, construction-grade lumber such as Douglas fir, spruce-pine-fir (SPF), or hemlock is used. Ensure that the lumber is straight, free of knots, and has a moisture content below 19%. The specific dimensions of the lumber will vary depending on the truss type and design.
The following table outlines the typical lumber sizes and grades used for different truss members:
| Truss Member | Lumber Size | Lumber Grade |
|---|---|---|
| Top Chord | 2×4 or 2×6 | Select Structural or #1 |
| Bottom Chord | 2×6 or 2×8 | Select Structural or #1 |
| Web Members | 2×4 or 2×6 | Select Structural or #2 |
| Bridging | 1×4 or 1×6 | #2 or #3 |
Calculating Truss Dimensions
Calculating truss dimensions is a crucial step in designing and constructing a successful truss structure. Here’s a detailed guide to help you determine the appropriate dimensions for your truss:
1. Span Length
The span length is the horizontal distance between the supports of the truss. It determines the overall length of the truss and the loads it can carry. Measure the span length accurately to ensure a stable structure.
2. Truss Height
Truss height refers to the vertical distance from the bottom chord to the top chord. It affects the strength and stability of the truss. Taller trusses generally withstand higher loads, while shorter trusses provide a lower profile.
3. Member Dimensions
Truss members include the top chord, bottom chord, and web members. Each member’s dimensions impact the overall strength of the truss. To determine appropriate member dimensions, consider the following factors:
| Factor | Description |
|---|---|
| Load Magnitude | The weight and forces that the truss will be subjected to determine the size and strength of the members. |
| Material Properties | The strength, stiffness, and density of the materials used for the members influence their dimensions. |
| Truss Geometry | The shape and configuration of the truss affect the distribution of forces and stresses, influencing the dimensions of the members. |
Assembling Bottom Chords
After cutting the bottom chords to length, the next step is to assemble them. This can be done by placing the chords on a flat surface and nailing them together at the ends. It is important to make sure that the chords are square and that the nails are driven straight through the chords.
Once the bottom chords are assembled, they can be attached to the posts. This can be done by nailing the chords to the posts or by using joist hangers. If joist hangers are used, they should be installed according to the manufacturer’s instructions.
The bottom chords are now complete and the next step is to assemble the top chords.
Here are some tips for assembling bottom chords:
| Tip | Description |
|---|---|
| Make sure the chords are cut to length. | This will ensure that the truss is the correct size. |
| Use a level to make sure the chords are square. | This will help to prevent the truss from sagging. |
| Drive the nails straight through the chords. | This will ensure that the chords are securely attached to each other. |
| Use joist hangers to attach the chords to the posts. | This will make the connection stronger and more durable. |
Installing Top Chords
Installing the top chords of a truss is a crucial step in truss construction. The top chords form the upper part of the truss and are responsible for carrying the weight of the roof. Here’s a detailed guide on how to install top chords:
1. Mark the Locations of the Top Chords
Determine the exact locations of the top chords on the truss using the truss layout diagram. Mark these locations with a pencil or chalk.
2. Position the Top Chords
Align the top chords with the marked locations and square them to the overall truss assembly. Secure the top chords temporarily using clamps or nails to prevent movement.
3. Install Spacers
If required, insert plywood or metal spacers between the top chords and the truss members below. These spacers ensure proper spacing and prevent the top chords from sagging.
4. Secure the Top Chords
Once the top chords are positioned correctly, fasten them to the truss members using truss screws or bolts. Drive the fasteners at an angle through the top chords and into the supporting members. Countersink the fasteners below the surface of the wood to ensure a flush finish.
5. Reinforce the Top Chords
In some cases, top chords may require additional reinforcement to withstand heavy loads or specific design requirements. Here are some common reinforcement techniques:
| Reinforcement Technique | Description |
|---|---|
| Gussets | Metal plates that are attached to the joints between the top chords and the supporting members, providing added strength. |
| Vertical Web Members | Additional members that are installed perpendicular to the top chords, connecting them to the bottom chords or other structural elements. |
| Laminated Top Chords | Building up the top chords by gluing or nailing multiple pieces of wood together, creating a thicker and stronger member. |
Adding Web Members
Web members connect the top and bottom chords, providing structural stability to the truss. They are typically placed at regular intervals along the truss’s length.
Types of Web Members:
Web members can be:
- Diagonal
- Vertical
- Horizontal
Diagonal web members are the most common type. They create a triangular shape that helps resist bending and shear forces. Vertical web members provide additional support against vertical loads, while horizontal web members help transfer loads between top and bottom chords.
Sizing and Spacing:
The size and spacing of web members depend on the size and load capacity of the truss.
General guidelines for sizing and spacing include:
| Web Member Type | Size | Spacing |
|---|---|---|
| Diagonal | 1/4 to 1/3 of chord depth | 6 to 12 feet |
| Vertical | 1/4 to 1/2 of chord depth | 3 to 6 feet |
| Horizontal | 1/6 to 1/4 of chord depth | 2 to 4 feet |
Installation:
Web members are typically installed by bolting or welding them to the chords.
Proper installation techniques are crucial to ensure the structural integrity of the truss.
Reinforcing with Gussets
Gussets are used to transfer loads and prevent the truss members from pulling apart at their joints. They are usually made of plywood or steel and are attached to the truss members using nails, screws, or bolts. The size and type of gusset will vary depending on the load that it is required to transfer.
Gussets can be used to reinforce any type of truss, but they are most commonly used in roof trusses. This is because roof trusses are subjected to high loads from wind and snow, and gussets can help to prevent the truss from failing. Gussets can also be used to reinforce floor trusses and other types of structures.
When designing a truss, it is important to consider the loads that it will be subjected to and the size and type of gussets that will be required to reinforce the truss. A qualified engineer can help you to determine the appropriate gusset size and type for your specific application.
Factors to Consider When Selecting Gussets
When selecting gussets, you should consider the following factors:
- Load: The load that the gusset will be subjected to.
- Material: The material that the gusset will be made of.
- Size: The size of the gusset.
- Thickness: The thickness of the gusset.
- Shape: The shape of the gusset.
- Attachment: The method that will be used to attach the gusset to the truss members.
- Cost: The cost of the gusset.
Table of Gusset Types
The following table provides a general overview of the different types of gussets that are available:
Gusset Type Material Size Thickness Shape Attachment Cost Plywood Plywood Varies Varies Rectangle or square Nails or screws Low Steel Steel Varies Varies Rectangle or square Bolts or screws Moderate Angle iron Angle iron Varies Varies L-shaped Bolts or screws High Fabricating Truss Ends
Fabricating truss ends involves cutting, shaping, and assembling the individual members that make up the ends of a truss. This process is critical to ensure the structural integrity and performance of the truss.
The following steps outline the general process of fabricating truss ends:
- Cutting the Members: The first step is to cut the individual members to the specified lengths and angles using a saw or cutting torch.
- Shaping the Members: If necessary, the members may need to be shaped or notched to accommodate the connections with other members.
- Drilling Holes: Holes are drilled in the members to allow for the insertion of bolts, nails, or other fasteners.
- Assembling the Ends: The individual members are assembled and fastened together to form the truss ends.
- Adding Gussets: Gussets, which are triangular plates, may be added to reinforce the connections between the members.
- Checking Dimensions: The fabricated truss ends are checked for dimensions and accuracy to ensure they meet the design specifications.
- Inspecting for Defects: The truss ends are inspected for any defects, such as cracks, splits, or misalignments, before being incorporated into the truss.
- Galvanizing or Painting: To protect the truss ends from corrosion, they may be galvanized or painted.
The specific fabrication methods and techniques used may vary depending on the type of truss, the materials being used, and the manufacturing equipment available.
Material Fabrication Method Wood Sawing, shaping, drilling, nailing Steel Cutting, welding, drilling, bolting Concrete Casting, reinforcing, curing Installing Supporting Brackets
When the top cord of the truss is in place, it’s time to attach the supporting brackets that will help hold it up. These brackets are typically made of metal and are designed to fit snugly over the top cord. They are usually attached using nails or screws, and they can be adjusted to provide the proper amount of support for the truss.
To install the supporting brackets, follow these steps:
- Measure and mark the location of the brackets on the top cord. The brackets should be spaced evenly along the length of the truss, and they should be positioned so that they will support the truss at the points where the joists will be attached.
- Drill pilot holes for the nails or screws. This will help prevent the wood from splitting when you drive the fasteners in.
- Attach the brackets to the top cord. Use nails or screws that are long enough to penetrate through the bracket and into the top cord.
- Adjust the brackets so that they provide the proper amount of support for the truss. The truss should be level and free of any sag.
Once the supporting brackets are installed, you can attach the joists to the truss. The joists are the horizontal members that run perpendicular to the top cord. They help to distribute the weight of the roof and ceiling.
To attach the joists to the truss, follow these steps:
- Measure and mark the location of the joists on the top cord. The joists should be spaced evenly along the length of the truss, and they should be positioned so that they will support the roof and ceiling at the proper locations.
- Drill pilot holes for the nails or screws. This will help prevent the wood from splitting when you drive the fasteners in.
- Attach the joists to the top cord. Use nails or screws that are long enough to penetrate through the joist and into the top cord.
- Adjust the joists so that they are level and free of any sag.
Step Description 1 Measure and mark the location of the brackets on the top cord. 2 Drill pilot holes for the nails or screws. 3 Attach the brackets to the top cord. 4 Adjust the brackets so that they provide the proper amount of support for the truss. Finishing Touches
1. Check for Squareness
Use a carpenter’s square to ensure that the two triangular sides of the truss are perpendicular to the bottom chord.
2. Measure and Cut Purlin Supports
If using purlins, measure the distance between the nodes where they will rest. Cut supports for the purlins to the measured length and install them.
3. Install Bracing
Bracing is essential for truss stability. Install diagonal braces between the nodes to prevent any movement or distortion.
4. Reinforce Joints
Use gussets or metal plates to reinforce the joints between the members of the truss. This increases the strength and durability of the structure.
5. Add Plywood Sheathing
If you’re using the truss for roofing, add plywood sheathing to the bottom of the truss to form the decking surface.
Inspection
1. Visual Inspection
Thoroughly inspect the truss for any damage, cracks, or loose connections. Check that all members are properly aligned and secured.
2. Laser Leveling Test
Use a laser level to check the levelness of the truss. Ensure that the two triangular sides are parallel and the bottom chord is horizontal.
3. Deflection Test
Apply a load to the truss and measure the deflection. The deflection should be within acceptable limits according to the design specifications.
4. Sound Test
Tap on the members of the truss with a hammer. Healthy members should produce a solid, resonating sound. If you hear any hollow or muffled sounds, it could indicate damage or a defect.
5. Bolt Tightness Check
Use a torque wrench to ensure that all bolts are tightened to the specified torque. Loose bolts can compromise the integrity of the truss.
6. Hardware Inspection
Examine the connectors, nails, and screws used in the truss construction. Replace any damaged or corroded hardware to prevent structural failure.
7. Moisture Content
Check the moisture content of the wood used in the truss to ensure that it’s within acceptable limits. Excessive moisture can lead to swelling, rot, and weakening of the truss.
8. Fire Resistance
If the truss is intended for use in a fire-prone area, verify that it meets the required fire resistance ratings.
9. Documentation
Keep a record of all inspections and maintenance performed on the truss. This documentation will serve as a valuable reference for future use.
How To Make A Truss
A truss is a structural framework that is used to support a roof or other structure. It is made up of a series of beams or trusses that are connected together in a triangular shape. Trusses are used in a variety of applications, including bridges, buildings, and aircraft.
To make a truss, you will need the following materials:
- Beams or trusses
- Connectors
- Screws or nails
- Measuring tape
- Level
Once you have your materials, you can begin to assemble the truss. First, lay out the beams or trusses in the desired shape. Then, connect the beams or trusses together using the connectors. Finally, secure the connections with screws or nails.
Once the truss is assembled, you can install it in the desired location. Trusses are typically installed using a crane or other lifting device.
People Also Ask
What is the best way to connect beams or trusses?
The best way to connect beams or trusses is to use connectors that are designed specifically for that purpose. These connectors will help to ensure that the truss is strong and stable.
What is the difference between a truss and a beam?
A truss is a structural framework made up of beams or trusses that are connected in a triangular shape. A beam is a single structural member that is used to support a load.
