When should you use joist hangers?

Joist hangers are an important component in many construction projects. They provide a strong connection between joists and headers or beams. Knowing when to use joist hangers can ensure your structure is sturdy and built to last.

What are joist hangers?

Joist hangers are metal brackets used to attach joists to headers or beams. The hangers have a U-shaped design that allows the joist to rest inside while nails or screws are driven through the sides into the wood. This creates a strong, secure connection.

Joist hangers come in a variety of sizes and styles to accommodate different joist widths and connection details. Some common types include:

• Standard joist hangers – for connecting joists to headers in floor and ceiling framing
• Joist end hangers – for attaching joists to beams or larger joists when they run perpendicular
• Adjustable hangers – with movable sides to allow for any joist width
• Skewed hangers – for connecting joists at an angle rather than perpendicular

Joist hangers are typically made from galvanized steel for corrosion resistance, but stainless steel hangers are also available for extra durability.

When are joist hangers required?

Building codes often dictate when it’s mandatory to use joist hangers in your construction project. Failing to follow code requirements could result in structural problems down the road.

Here are some of the most common instances where building codes require joist hangers:

• Connecting joists to headers and beams – This is one of the most frequent uses for hangers. They provide a stronger tie between the joists and framing members than toenailing.
• Joist connections at bearing walls – Hangers must be used when joists run parallel to and sit on top of load-bearing walls.
• Joist tails – The ends of joists that extend past a beam or ledger board must be supported with joist hangers.
• Floor openings – Hangers are required where joists surround large floor openings like stairwells or chimneys.
• Supported joist spans – Codes often regulate the maximum distance between joists. Hangers must be used at the connections when the limit is reached.

Be sure to consult your local building codes to determine exactly where joist hangers are mandatory in your area and for your specific project.

When are joist hangers recommended?

While building codes provide minimum requirements, there are many other instances where using joist hangers is highly recommended even if not technically required.

Some examples of where joist hangers are recommended include:

• Connections subject to vibration – Hangers reduce movement that can loosen connections over time.
• Structures in high wind or seismic zones – The rigidity added by hangers results in better wind and earthquake resistance.
• Heavy load-bearing joists – For joists supporting heavy distributed loads like a media room, hangers help strengthen the connections.
• Structural modifications – Hangers should be used whenever joists are added or relocated in an existing structure.
• Exposed outdoor connections – Outdoor connections benefit from added corrosion resistance of joist hangers.

Keep in mind that anytime joists are carrying heavier loads than a typical floor, adding joist hangers is a good idea for extra strength and rigidity.

Benefits of using joist hangers

Now that we’ve covered common instances when joist hangers are required or recommended, let’s take a closer look at some of the benefits they provide:

• Stronger connections – Joist hangers rigidly attach joists to framing members for better transfer of loads. The metal brackets are much less likely to loosen over time than toenailed connections.
• Consistent connections – Hangers virtually eliminate human error that can occur when hand-toenailing joists. Each connection is reliably constructed to the same specifications.
• Faster installation – Attaching a joist with nails or screws driven into a metal hanger is much faster than toenailing.
• Accommodate design changes – Hangers allow for easier modifications like relocating or adding joists compared to toenailing.
• Provide lateral stability – The rigidity of joist hangers helps minimize lateral movement and vibration.

By providing these advantages, the relatively low cost of joist hangers can pay dividends when it comes to structural integrity and peace of mind.

Disadvantages of joist hangers

There are really only a few potential drawbacks to using joist hangers in most cases:

• Slightly higher material cost compared to toenailing
• Require time to install properly
• May not fit in tight spaces between closely spaced framing members
• Provide minimal resistance to uplift on its own

However, these disadvantages are generally outweighed by the performance benefits that joist hangers provide in most applications.

Load values for joist hangers

One key factor to keep in mind when selecting joist hangers is the load values. Manufacturers test hangers to determine the maximum loads they can handle under different conditions. This allows you to select a properly rated hanger for the expected load on a particular joist. Basic load values to look for include:

• Tension loads – The downward force a hanger can withstand when supporting a joist. Given in pounds or kN.
• Compression loads – The upward force a hanger can handle when supporting a joist. Measured in pounds or kN.
• Lateral shear loads – The side-to-side force a hanger can resist at the joist-hanger connection. Stated in pounds or kN.

Be sure to choose hangers rated for tension, compression, and lateral loads that meet or exceed the expected loads. This ensures the hangers do not fail under the design loads. Overloading a joist hanger risks severely compromising the connection.

How to install joist hangers

While joist hanger installation is relatively straightforward, following best practices ensures you construct secure, long-lasting connections:

1. Confirm the hanger fits the joist and header/beam properly. Make any adjustments needed to the framing lumber dimensions.
2. Attach the hanger securely to the header or beam using all specified nail and screw holes.
3. Set and center the joist into the hanger. The joist end should be flush with the header/beam face.
4. Drive nails or screws through the side holes of the hanger into the joist per the manufacturer specifications.
5. Bend any tabs to lock the joist in place and prevent uplift.
6. Double check that all specified fasteners have been properly installed.

Be sure to follow the joist hanger manufacturer’s instructions for correct fasteners and quantities. Using too few fasteners or the wrong type can seriously compromise performance.

Special considerations

There are a few special cases that require additional care when installing joist hangers:

• Skewed connections – Use skewed or sloped hangers matched to the joist angle.
• Steel framing – Self-tapping screws must be used instead of nails for steel headers/beams.
• Outdoor exposure – Use stainless steel hangers and fasteners in wet, corrosive environments.
• Treated lumber – Nails and screws must be compatible with the chemical treatment.

Be sure to take these kinds of factors into account when selecting and installing hangers for specialized conditions.

Conclusion

In summary, joist hangers are essential in many construction applications to create rigid, lasting connections between joists and headers/beams. Building codes lay out minimum requirements, but hangers are recommended even more broadly anytime enhanced strength and consistency are needed. Just be sure to match the correct hanger capacities to the expected structural loads. With quality joist hanger installation, you can achieve secure, durable framing in your construction projects.