Joist hangers are metal brackets that are commonly used to attach floor joists to headers, beams, or foundation walls in home construction and remodeling projects. But can these handy metal brackets also be used when installing floor joists? The short answer is yes, joist hangers are perfectly acceptable for supporting floor joists in many situations.
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What Are Joist Hangers?
Before diving into using joist hangers for floors, let’s first take a quick look at what exactly joist hangers are and how they work. Joist hangers are L-shaped metal brackets that have small ‘tabs’ or ‘flanges’ on the inside of the vertical part of the ‘L’. These tabs allow joists or beams to be rested inside the hangers.
The horizontal bottom portion of the joist hanger gets fastened to a header beam or foundation wall. Once installed, joist hangers provide a strong metal-to-metal connection that securely supports the joists and transfers the load down into the structure.
Joist hangers are available in a range of sizes to accommodate different lumber dimensions. Common types include:
- 2×4 joist hangers
- 2×6 joist hangers
- 2×8 joist hangers
- 2×10 joist hangers
- 2×12 joist hangers
Joist hangers are normally made from galvanized steel for corrosion resistance, but stainless steel hangers are also available for demanding environments like coastal areas. While the standard hangers have a fixed 90 degree angle, specialty hangers such as 45 degree corner hangers are also made.
Advantages of Using Joist Hangers
Now that we know what joist hangers are, what are the advantages of using them to support floor joists?
Uniform Support and Load Transfer
One of the biggest advantages of joist hangers is that they provide uniform support for each joist. The metal-to-metal connection gives an evenly distributed bearing surface that helps transfer loads properly down into the structure.
This helps prevent problems like twisting or cracking that can occur in joists if loads are concentrated in certain areas or not transferred correctly.
Speeds Up Construction
Installing joists into hangers is much faster than having to cut joist seats into beams or ledgers. It also eliminates the time-consuming process of toe-nailing joists in place. The total time savings can really add up over the many, many joist connections in a typical floor system.
Strong and Secure Connection
The fixed metal connection of a hanger provides a stronger, more secure joint than typical wood-to-wood connections like toe-nailing. Joist hangers maintain their rigidity over time much better than wood connections which can work loose or deteriorate with slight wood movement.
Consistent Placement and Spacing
Using hangers allows joists to be installed with great precision and consistency. The uniform shape of the hangers makes it easy to line up joists and achieve the proper spacing. This level of consistency is hard to obtain when hand cutting individual seats or trying to toe-nail joists accurately.
Versatile and Adaptable
Joist hangers come in a wide range of sizes and designs to accommodate many scenarios. There are models specific to certain structural connections like hangers made for attaching joists to foundation walls. The installer can also make minor modifications to the hangers if needed. Their inherent flexibility makes joist hangers a very versatile structural connector.
Considerations for Using Joist Hangers on Floors
While joist hangers offer many advantages, there are some important considerations to keep in mind when using them for floor joist connections specifically:
Hanger Size
Be sure to use the properly sized hanger for the joist dimensions. The joist should fit snugly within the tabs of the hanger with minimal side-to-side movement. Oversize hangers will not grip the joist properly.
Load Capacity
Select hangers rated for the anticipated load on that part of the floor system. Heavier loads require hangers with higher load capacities. Exceeding the hanger’s load capacity can lead to failure.
Installation Quality
Joist hangers must be installed correctly to function as designed. They need to be properly fastened to the supporting structure with the specified type, size, and quantity of fasteners. Improper installation can severely compromise strength.
Wood Treatment
Use corrosion-resistant joist hangers when installing treated lumber. The chemicals used to preserve treated wood can react with and corrode regular steel hangers.
Blocking Considerations
Hangers alone do not prevent joists from twisting. Additional blocking is typically required between joists for floor stability. Account for any needed blocking when planning joist placement in hangers.
Top Flange Load Transfer
Hangers usually only support the vertical gravity load of the joist. Make sure load from the top flange of the joist is properly transferred into the ledger or header by other means like joist nails.
Joist Hanger Installation Tips
To get optimal performance from joist hangers as floor joist supports, follow these tips for installation:
- Use only high-quality, corrosion-resistant hangers that match the joist size.
- Install hangers using the specified type and quantity of nails or other fasteners.
- Make sure top and bottom flanges are properly supported.
- Fit joists snugly into hangers without excessive side movement.
- Use proper joist spacing for the floor system needs.
- Add supplemental blocking between joists as needed.
- Inspect for damaged or defective hangers and replace if found.
- Consult the building code for any special requirements in your area.
Creating a Solid Floor with Joist Hangers
Used properly, joist hangers are a great choice for connecting and supporting floor joists. Here is a step-by-step overview of how to build a strong, solid floor system using joist hangers:
- Install ledger boards around the perimeter where the floor joists will bear. Bolt securely to foundation wall.
- Determine joist size and spacing needed. Select proper joist hangers for size and load.
- Lay out joist locations on ledger boards based on desired joist spacing.
- Pre-install joist hangers on ledger boards at joist layout marks.
- Measure, cut, and install joists into pre-installed hangers.
- Add supplemental blocking between joists as required.
- Install floor sheathing atop joists to tie floor system together.
- Install trim, finish flooring materials as desired.
The use of joist hangers allows each step to be completed efficiently while ensuring a solid underlying floor that will provide many years of service.
Common Questions
Do joist hangers need to be nailed?
Yes, joist hangers rely on nails or other approved fasteners to securely anchor the hanger and transfer forces properly. Hangers should be nailed according to the manufacturer’s instructions using the specified type, size, and quantity of fasteners.
Should all floor joists be hung with joist hangers?
It is recommended, but not always required, to use joist hangers for all floor joist connections. Hangers provide consistency and help prevent problems over time. Some building codes require the use of hangers on certain types of floor joist connections.
How much weight can a joist hanger support?
The load capacity of a joist hanger depends on several factors:
- Material – stainless steel offers higher capacities than galvanized steel.
- Hanger design – some specialty hangers can support more load.
- Joist size – wider joists distribute load better.
- Fasteners – more and larger fasteners increase capacity.
- Wood strength – certain wood species are stronger than others.
Typical joist hanger capacities range from 500 lbs for a small 2×4 hanger, up to several thousand lbs for a heavy duty hanger.
Do joist hangers need to be galvanized?
Galvanization is crucial for joist hangers made of standard steel. It applies a protective zinc coating that prevents rusting and corrosion. Galvanized hangers can be used both indoors and outdoors. Indoor-only hangers are available without galvanization, but these will quickly corrode if exposed to moisture or weather.
Should I nail both sides of a joist hanger?
It is generally recommended to nail both sides of a joist hanger for maximum strength. However, some hangers are designed to be nailed on just one side. Always check the manufacturer’s instructions to determine the required fastening pattern for that specific hanger.
Conclusion
Joist hangers provide an efficient, high-strength connection option for supporting floor joists. When properly installed, they offer many advantages over typical wood-to-wood joints. However, care must be taken to select the correct size and type of hanger, install them properly, and account for supplemental blocking needs. Following the recommendations outlined above will allow you to construct a solid, long-lasting floor system using joist hangers.