One of the most common errors in any project is using the wrong screw. Taking the time to confirm you have the correct fastener before driving the first screw will help you prevent damage and make your project last.

Every application has unique needs, and screws vary in length, thickness, material, and design—each aspect affecting performance. Knowing the demands of your material is the first step toward choosing the right screw and ensuring a successful project.

Know What You're Working With

The surface you are driving into is the most important consideration when selecting a screw. You can create reliable, long-lasting results by matching the screw you use to the material, thickness, and purpose of your project, as different screw types are designed to handle different conditions. 

Material

What is the surface made of? 

• Hard materials such as hardwoods, plastics, or metals require sturdier screws with thicker shafts. 
  • We recommend using self-tapping screws or pre-drilling pilot holes for these applications. 
• Soft materials like drywall, softwoods, or soft plastics are better suited for thinner screws with lower torque requirements.
  • Washers can help prevent the screw head from crushing soft surfaces. 
• Metal applications may corrode if mixed metals are exposed to moisture. Wet outdoor environments may require extra precautions, such as matching screw and surface metals or using washers or coated screws.
  • Stainless steel screws are most resistant to corrosion.
• Treated wood requires corrosion-resistant fasteners, such as stainless steel or zinc-coated screws.
  
  • Look for ACQ-rated screws when shopping for these projects

Thickness

The thickness of the material you are using is important to consider when selecting a fastener, because screw length has a big impact on performance. 

A screw that is too short will not offer enough holding power, but a screw that is too long may break through or damage the material. The screw should be long enough to grip the material below the surface without sticking out the other side.

A common rule of thumb for many projects is to use a screw that is 2.5 times longer than the top board.

Purpose

Finally, consider the location and intended use of your project. 

• Heavy loads or structural applications require additional support, such as larger screws or a greater number of fasteners. 
• Outdoor applications require coated or corrosion-resistant screws to withstand exposure to moisture and weather. 

After selecting the right screw for the job, the next step to a successful project is thoughtful design planning. Just as important as the fastener itself are the quantity and placement of screws. Poor design choices can place unnecessary stress on fasteners and lead to premature failure, even when high-quality screws are used. 

In this section, we will learn how to avoid common design mistakes, including using too few screws, improper placement, and skipping necessary supports. 

Insufficient Quantity

When working with large or load-bearing pieces, it is critical to provide support at multiple points. Even the strongest screw on the market is not designed to bear an entire load on its own. Using too few fasteners concentrates stress and increases the risk of loosening, damage, or failure. 

In most cases, it is better to use more screws than required, because distributing the load across multiple fasteners improves stability and security. 

Improper Placement

Screws have stronger shear strength (force applied horizontally across the screw) than tensile strength (force pulling the screw straight out). 

For this reason, screws should be placed so that force is applied perpendicularly to the screw rather than along its length. Screws are more likely to loosen or fail if they are supporting a load primarily through tensile strength.

Skipping Support Components

In many applications, a screw alone is a sufficient fastening solution, but some situations require additional support to ensure a secure and long-lasting connection. One simple but often overlooked addition is a washer. 

Washers are placed between the screw head and the surface, and their primary purpose is to distribute the load, reduce friction, and protect the surface. A washer may be useful if: 

• Driving into a soft surface
• Using a screw with a small head
• The structure will experience frequent movement or vibration
• You want to protect the surface from damage

You may not need a washer if: 

• You are using a screw with a pan, wafer, or modified truss head, which already distribute load effectively. 
• The application is metal-to-metal, where the screw head sits flush on the surface. 

Even with the right screw, mistakes can still occur during application. Common installation errors include "walking," split material, and stripped screws, all of which can cause misalignment, material damage, or fastener failure. But with the right tools and technique, these mistakes can easily be avoided.

Overdriving is a frequent cause of many issues and should always be avoided—remember to stop driving as soon as the screw is snug.

&nbsp

Walking

"Walking" occurs when the screw tip drifts away from the insertion point instead of biting into the surface. The screw ends up off-target, which can damage structure strength and visual appeal. 

Walking may be due to:

• Screws not gripping the surface
  • There is no pilot hole or starter divot
  • You are using the wrong screw tip
  • The surface is hard or slick
• Applying too much torque—starting the driver too fast
• Using reused or dull screw tips
• Applying sideways pressure while starting

Walking screws can cause: 

• Misaligned parts
• Scratched or damaged surfaces
• Reduced holding strength

Prevent screws from walking by:

• Drilling pilot holes or using a screw designed for easy driving
  • If driving into wood, use a type-17 point screw
  • If driving into metal, use a self-tapping screw
• Driving the screw slowly until threads bite
• Applying firm, straight pressure to the driver

Splitting

Splitting occurs when wood cracks or splinters as a screw is inserted. 

Splitting may be due to: 

• Using a screw that is too large for the material
• Placing the screw too close to the surface edge
• Driving into a dry or brittle material
• Overdriving the screw

Split material can cause: 

• Reduced holding strength
• Cracked or broken surfaces
• Joint failure over time
• Poor appearance

Prevent your material from splitting by:

• Drilling pilot holes or using self-drilling screws
• Inserting screws farther away from surface edges
• Using thinner screws, if possible without sacrificing structural integrity
• Stopping driving when the screw is snug—don't overtighten
• Lubricating screws with wax or soap before driving

Stripping

Stripping occurs when either the screw head or threading is shaved away during installation, potentially weakening its holding strength and making it difficult to use.