A hanger in construction is a metal connector that supports one structural member from another, most commonly securing a joist or beam so it stays locked in position without resting on a ledge. The most familiar type is the joist hanger, a U-shaped bracket made of galvanized steel that wraps around the bottom and sides of a joist and fastens it to a beam, wall, or header. Hangers show up everywhere in building, from floor framing and deck ledgers to ductwork and plumbing runs.
How Structural Hangers Work
In wood-frame construction, horizontal members like joists and beams need a reliable connection wherever they meet another framing member. The simplest approach is to rest the end of a joist on top of a beam, but that isn’t always possible. When a joist frames into the side of a beam or ledger board, there’s no surface to rest on. A joist hanger solves this by creating a metal seat that transfers the load through nails or screws driven into both the joist and the supporting member.
The hanger itself does two things: it resists the downward gravity load (keeping the joist from dropping) and, when fully fastened, it resists uplift forces from wind or seismic events. The steel of the hanger carries the weight, while the fasteners transfer that load into the surrounding wood. If any part of this system is undersized or missing, the connection weakens.
Where Building Codes Require Them
The International Residential Code spells out when hangers are mandatory. Each joist, beam, or girder must have at least 1½ inches of bearing on wood or metal, or at least 3 inches of bearing on masonry or concrete. If you can’t meet those minimums, you need an approved joist hanger. Deck construction is especially strict: any joist framing into the side of a ledger board or beam must be supported by an approved hanger, with no exceptions.
Types of Structural Hangers
Joist hangers come in a wide range of sizes and configurations to match different lumber dimensions and connection angles. The main categories include:
- Face-mount hangers: The most common type. The back flange sits flat against the beam or header, and the hanger’s U-shaped seat wraps the joist. Available for everything from 2x4s to engineered lumber.
- Top-flange hangers: These hook over the top of a beam rather than nailing into its face, useful when you can’t access the back side of the supporting member.
- Skewed and sloped hangers: Designed for connections where the joist meets the beam at an angle other than 90 degrees, either tilted sideways (skewed) or pitched up or down (sloped). Using a standard hanger for an angled connection is a common and serious installation error.
- Concealed-flange hangers: Built so the metal flanges tuck between the joist and the beam, hiding the hardware from view. These are popular in exposed-beam construction where visible steel would spoil the look of finished timber.
- Masonry and concrete hangers: Engineered for attaching wood framing to concrete block walls or poured concrete. These often embed into grout-filled masonry units and may include uplift resistance for high-wind regions.
Hangers for Pipes, Ducts, and Conduit
The word “hanger” in construction doesn’t only refer to structural framing. Mechanical, electrical, and plumbing trades use a whole family of hangers to suspend pipes, ductwork, and conduit from overhead structure. These serve a different purpose: they hold system components in place while allowing for thermal expansion, vibration, and maintenance access.
Common types include clevis hangers (a U-shaped yoke that cradles a pipe and hangs from a threaded rod), band hangers (a simple metal strap that wraps around a pipe), J-hangers (a hook-shaped support for smaller lines), and spring hangers (which absorb movement in hot-water or steam piping). For uninsulated pipes 2 inches and smaller, ring hangers, swivel bands, or J-hangers all work. Pipes 2½ inches and larger typically call for the heavier clevis style.
Materials and Corrosion Protection
Most structural hangers are stamped from steel and coated to resist rust. The level of coating you need depends on where the hanger will live.
Standard galvanized hangers carry a G90 zinc coating, roughly 0.90 ounces of zinc per square foot of surface. This is adequate for interior, dry applications like floor framing inside a conditioned house. For moderate exposure, such as a covered porch or a region with occasional humidity, a heavier galvanized coating (sometimes marketed as ZMAX, at 1.85 ounces of zinc per square foot) provides roughly double the protection.
Pressure-treated lumber accelerates corrosion because the chemicals in the wood attack standard zinc coatings. Any hanger in contact with treated wood needs at minimum the heavier galvanized option. For coastal or saltwater environments, stainless steel hangers are the right choice. Type 304 stainless works in most corrosive settings, while type 316, which contains molybdenum, handles severe chloride exposure like oceanfront construction.
Common Installation Mistakes
Hanger failures almost always trace back to installation errors, not to the hanger itself. The most frequent problems are straightforward: using the wrong number of fasteners, using the wrong size fasteners, and leaving nail holes empty.
Every hole in a joist hanger is there for a reason. The holes in the back flange (the part nailed to the beam) carry shear loads. The holes in the seat flanges resist uplift. Skipping even a few nails can dramatically reduce the connection’s rated capacity. A hanger missing its double shear nails, for example, loses its uplift resistance entirely.
Fastener size matters just as much. Hanger manufacturers specify short, fat nails (often called “joist hanger nails” or “teco nails”) rather than standard framing nails because the thicker shank resists withdrawal better. Using a 16d sinker instead of the specified 10d x 1½-inch hanger nail changes the geometry inside the hole and can split the wood or miss the joist entirely. Screws are only acceptable if they are specifically rated for hanger use; standard drywall or deck screws are brittle and can snap under shear.
The other common error is using a non-sloped hanger on a sloped connection. When a rafter or joist meets a beam at a pitch, the load hits the hanger at an angle it wasn’t designed for, concentrating stress on the steel and fasteners in ways the rated load tables don’t account for.
How Hangers Fail
When a properly chosen hanger does reach its limit, failure typically follows one of a few patterns. The wood can crush around the fasteners, especially if the lumber is soft or the grain runs perpendicular to the load. The nails can withdraw from the wood if penetration is too shallow or the wood’s density is low. In extreme overloads, the steel of the hanger can buckle or tear at a bend point. In practice, most real-world failures are a combination: the wood crushes slightly, which loosens the nails, which allows the joist to rotate and drop. This is why full nailing is so important. Each fastener shares the load, so losing capacity at one nail doesn’t cascade into collapse.