Before hanging or mounting any objects on the drywall, it's important to find out how much weight drywall can hold. Simply driving a few screws through a bare sheet of drywall may be effective for supporting lightweight pictures, but if you attempt to hang anything substantial, like a small shelf, the weight of the object will pull the screws through the drywall.
Find out how much weight drywall can hold.
Interior Wall Construction
In order to determine the best mounting method, it's necessary to have a better understanding of interior wall construction. Most interior walls consist of a framework of 2x4s that form the structure of the wall. The gaps between the framework is generally filled with insulation, though drain lines, water lines, and wiring may also run through these gaps.
Drywall sheets are mounted to the framework, covering up the interior structure of the wall. The drywall is then taped, mudded, and painted to seal the walls against moisture. To avoid drilling into a water line, driving a nail through a drain pipe, or mounting an object to bare drywall, use a stud finder to locate the studs behind the wall.
Due to the low strength and durability of drywall sheets, most objects cannot be hung directly on drywall without proper positioning and the right hardware to secure the weight to the drywall.
The framework of 2x4s behind the drywall is made up of horizontal headers, top plates, bottom plates, sills, and fire blocks. It is also constructed with vertical top cripples above window openings, bottom cripples below window openings, and studs that run from the bottom plate to the top plate. When hanging objects on drywall, locate the studs behind the drywall with a stud detector.
After locating the studs, you can plan the best position for the object, ensuring that it is secured to both the stud and the drywall with the appropriate hardware. While drywall alone can hold about 1.6 pounds to 2 pounds per square foot, mounting an object to the stud with the proper hardware allows the drywall to support up to 100 pounds.
Similar to wall studs, ceiling joists help support the structure of the above floor and the ceiling. Drywall sheets are typically mounted to the beams and ceiling joists running through the ceiling, before the drywall is taped, mudded, and painted. Ceiling joists cannot support the same amount of weight as a wall stud, so before mounting ceiling fans, light fixtures, or any other objects, consider the weight limit of the structure. On average, a ceiling joist can support about 15 to 20 pounds, though you may be able to increase this limit to 30 pounds if the ceiling joists are reinforced with blocking.
After finding a stud or joist to secure the object, you will want to determine the best hardware to help hold the weight of the object. Anchors are common options for mounting objects to drywall, including expansion, simple threaded, straight plastic, and winged plastic anchors.
- Expansion anchors are also known as drywall plugs. These anchors slide into pre-drilled holes, then when a screw is driven into the anchor, the anchor expands out to grip the sides of the hole. Expansion anchors are suitable for small pictures or any items that weigh between five to 20 pounds.
- Simple threaded anchors can hold between 25 to 75 pounds, making them a better option for mounting shelving or TVs. These anchors are also known as self-drilling anchors because they do not need a pilot hole prior to installation. However, simple threaded anchors are not well-suited for ceiling mounts.
- Straight plastic anchors have a cylindrical shape and several ridges that are used to grip the drywall. When a screw is driven into the anchor, the split tip flares out to prevent the screw from sliding out of the drywall. However, these anchors are relatively weak, so they should only be used with objects that weigh about five to 20 pounds.
- Winged plastic anchors are similar to straight plastic anchors in that they should only be used for objects that weight about five to 20 pounds. These anchors have a wing-shape design that spreads outward when the anchor is pushed through a pilot hole in the drywall. The wings help spread the weight of the mounted object over a greater distance, while preventing the anchor from being pulled out of the wall.
Toggle bolts and molly bolts are two additional types of anchors that are useful for mounting objects to drywall. Plastic toggle bolts can hold objects that weigh up to 20 pounds, while metal toggle bolts are capable of supporting up to 100 pounds if the object is properly mounted to a wall stud. Molly bolts are also known as sleeve type anchors. These anchors are useful for both the wall and ceiling, though the weight limit differs significantly depending on the mounting location. Use Molly bolts to hold about 25 to 50 pounds on the wall or up to 10 ounces on the ceiling.
Hangers and Fasteners
The type of fastener you use can also influence the amount of weight the drywall can hold. If you opt for picture hangers or simple nails, then stick to objects that are less than 20 pounds. Flat mounted hooks and anchors may be able to hold up to 50 pounds, while drywall screws can hold about 20 pounds of weight. To support up to 100 pounds on drywall, make sure to find the wall studs, then mount the object using metal anchors and screws longer than 3/8-inch in length.