I’ve seen more than my fair share of preventable DIY mishaps over the years, simply because people don’t take the time to research. Knowing how much weight a screw can hold is something that every homeowner should know.
As a general rule, a screw can hold 80-100 pounds (36-45kg) in weight. Factors such as screw length, thread type, quality and condition, installation, and the forces placed on the screw all impact the amount of weight it can hold. Using anchors significantly increases the amount of weight they can bear.
The most important question is how a screw behaves in the material. You will also need to know how much weight you can hang from a screw before it breaks.
5 Factors That Determine How Much Weight a Screw Can Bear
The are many variations of screws, with some better for harder materials, extreme angles, or pulling forces. Screws come big and small, stiff, and soft. Here are the main factors that decide the suitability of a screw.
1. Screw Length
Thicker materials like half-inch OSB will need longer screws. Longer screws will ensure that there is a good amount of anchoring into the backing material. It is also true that you want to use a screw that’s 1 inch (25mm) or longer if you’re planning to hang something from the ceiling—even drywall.
The tensile strength of a 2-inch (50mm) screw is the same as a 1-inch screw
of the same diameter and material. But the extra length will make a dramatic difference in anchoring the screw.
A 2-inch screw means that you have more screw shaft to make it through the surface and into the backing support.
You also do not want the sharp end of a screw to poke through for someone to cut themselves on. Materials are unpredictable, and it is better to use more short screws than to rely on a single long screw.
2. Type of Screw Thread
Depending on the material, you want to choose the thread that best suits the materials that you are securing. There are two main types of screws: coarse and fine thread. Each has distinct advantages and disadvantages.
Fine threads work well on metals, where you either thread the metal or screw it into a nut. The fine thread takes longer to tighten but offers far more surface area for applying torque. Some masonry screws use fine thread bolts with metal anchors.
Coarse threads are more common for wood screws, drywall, and other softer materials. Their more distant thread gaps help to compress the material, forming a plug. You can use self-tapping screws, which also have coarse threads.
3. Quality of the Screw
The vertical strength of a screw will depend on its shaft width, the type of metal, and the manufacturer. Cheap steel screws will have around a third of the tensile resistance of an alloy screw. Often, the weight limit is not on the screw but on the material the screw is trying to hold in place.
Tempered screws are harder and more suitable for higher amounts of pulling force on the head. Softer screws are sometimes better for wood as they will bend as the wood expands and contracts during the winter.
Thicker screws can cope with shearing and pulling forces better. But the thicker the screw, the more they cost and the more effort they take to screw in. For wood, it’s better to go with a thinner screw to prevent it from sticking in or splitting the wood.
4. Method of Inserting the Screw
Drywall is brittle, and most screws will pull straight through the material before you can put any real torque on them. You can try larger screw heads, which is fine if you are attaching the drywall to the frame of a building.
Using wall anchors makes a big difference to the amount of weight you can put on a screw. With concrete, you will need to use either wood, plastic, or metal anchors for the screws. The tighter the anchor fits with the screw, the more weight it will be able to support.
You can also buy chemical or reactive anchors that mix with a preinjected resin. This resin fills all voids between the concrete and the bolt to prevent slippage. Chemical anchor bolts can support many thousands of pounds each.
5. Types of Force on the Screw
Most screws over 1-inch long with plastic anchors should support 100 pounds (45kg) or more if the entire screw makes it into the wall. The lateral force of drywall on a single screw is often low since many screws work together to hold up the material.
But since you cannot overtighten a screw into drywall without it pulling through, you cannot rely on friction alone to help. With wood to wood, metal to metal, or metal to wood, friction plays a real role. Lateral forces on the screws reduce as you tighten the screw, as you can rely more on the drag between the materials.
Frequently Asked Questions
How Much Weight Can Screws Hold Vertically?
A typical screw in a stud should be able to hold between 80 to 100 pounds (36-45kg). Though you should not rely on a single screw to hold up all that weight. Drywall will pull through a screw long before it supports 20 pounds (9kg).
How Much Weight Can Screws Hold on Drywall?
Normal screws will support up to 10 pounds (4.5kg) in drywall unless you use anchors. Anchors are useful if you want to hang a picture or mirror where there are no studs. You want to use one screw for every five pounds of weight you need to support.
How Much Weight Can a Stud Screw Hold?
High-end drywall anchors can improve a screw’s capability to over 100 pounds (45kg). A screw may be able to hold over 160 pounds (73kg) horizontally if the backing materials are solid like metal and wood—not drywall. Though you should not rely on a single screw to hold up all that weight.
How Much Weight Can Screws Hold in Brick?
You can find masonry screws that do not need anchors, but it is always better to drill a hole and add an anchor. A regular 1-inch screw-in brick, using a plastic anchor, should be able to support 100 pounds (45kg) before it pulls out.
How Much Weight Can Screws Hold in Wood?
A typical #8 screw is between 1 and 1.25 inches (25-31mm) long and has a shear strength of 90 pounds (40kg). This means that if you hung a picture greater than 90 pounds, there is a good chance that the screw would snap. Though if you use the same screw to secure thick plywood to the ceiling, it should be able to support up to 170 pounds (77kg).
How Much Weight Can Screws Hold in Plaster?
Plaster over drywall will do little to improve the hanging strength of a screw. Screws in plaster on drywall will support less than 10 pounds (4.5kg). By using an expansion screw in plaster over a concrete wall, the support strength can increase to over 200 pounds (90kg).
How Much Weight Can Screws Hold in Concrete?
Light-duty anchors will be good for 50 pounds (23kg) of hanging weight, and medium anchors should support over 100 pounds (45kg). Metal anchors and heavy-duty alloy screws may be able to support over 2000 pounds (907kg) if done right.
How Much Weight Can 1-Inch Screws Hold?
A short 1-inch (25mm) screw can still hold between 80 to 100 pounds(36-45kg) of material. Soft pine may not have the density to prevent a 1-inch screw from pulling out. Whereas medium to hardwoods will offer a much higher level of resistance to prevent pull-through.
How Much Weight Can a Two-Inch Screw Hold?
A two-inch (50mm) screw may still be limited to 100 pounds (45kg), but there is much less chance of the screw pulling out. Most drywall is less than a half-inch thick (13mm), so there is less need for screws longer than 1 inch to secure them.