Plastic materials such as polycarbonate panels provide many benefits to professional builders and are highly desirable for many agricultural projects. It can be used for ceiling or wall protection, or as sky or side lighting. Polycarbonate is known for its strength and durability. It is 20x stronger than glass, and it is temperature resistant. It provides excellent thermal insulation and allows 90% of light rays to pass through while blocking UV rays. 

Although it does not require special tools for installation, it does require special handling. There are a number of handling, installation, care, and maintenance guidelines builders need to follow in order to optimize the use and application of plastics such as polycarbonate. One of the most important requirements is pre-drilling. If you are not already familiar with pre-drilling, now is the time to learn as it is a critical part of the plastics installation process. Read on to learn everything you need to know about pre-drilling, the importance of pre-drilling, how you should pre-drill, how temperature affects drilling, and the benefits of pre-drilling.


What is Pre-Drilling

All products naturally expand and contract with changes in temperature. Because of this, all panels must be installed to allow for expansion and contraction. The first step in the best-practice, plastics installation process is perhaps the most important step. Pre-drilling is the first step and it will make or break your project. The stakes are especially high for large agricultural or building projects. Let’s talk about the definition of pre-drilling and how to do it right. 

Simply put, pre-drilling is the process of drilling a hole in the plastic material before drilling in the screw that will attach the sheeting to the support structure.  The general rule is that the pre-drilled hole must be 2/16 to 3/16” larger than the diameter of the shaft of the fastener. This allows the polycarbonate sheets from buckling around the screws as they expand and contact with changes in temperature. 

To properly pre-drill plastic panels, you need: 

  1. A hardwearing and heat resistant (HSS) drill bit that is larger than the diameter of the shaft of the fastener and has a 60 degree point. For Onduline polycarbonate panels, a 2/16 to 3/16” increase in diameter is ideal.
  2. A variable speed drill
  3. Locking pliers or glue clamps
  4. Masking tape
  5. Underlay material for the drill to penetrate
  6. A workbench or wood frame for support
  7. A measuring tape or ruler
  8. A pencil 

Pre-drilling is not as simple as taking a drill to a piece of plastic and pressing the on-button. Follow these steps to properly pre-drill plastics:

  1. Evaluate the plastic material and the fasteners you intend to use to secure the plastic to another surface. 
  2. Acquire the tools and materials you need to properly support and drill the plastic. 
  3. Support the plastic on a flat wood board and sturdy bench.
  4. Clamp the plastic to the board so that it stays in place during the drilling process.
  5. Apply masking tape to both sides of the area you plan to drill. 
  6. Measure and mark the position of the drill holes on the masking tape. 
  7. Position the drill perpendicular to the plastic sheet. 
  8. Run the drill at medium speed with light pressure and gently allow the bit to burrow into the plastic. Maintain a smooth and consistent pace until you drill through the plastic. 
  9. Assess the quality of the hole and refine the process and technique as needed. 
  10. Repeat this process until all of your holes have been drilled. 

Polycarbonate and Thermal Expansion

As polycarbonate is exposed to high temperatures, it experiences thermal expansion. Thermal expansion is the lengthening and growing of the material in response to the heat, and the contraction in response to the cold. To determine the amount your plastic material will expand and contract, consult with the manufacturer or reference the installation instructions. It is important to understand the rate at which your material will expand or contract so that the pre-drilled holes are the right size.

How Heat Affects Drilling

As we know, heat causes the plastic material to expand. If the plastic material is not pre-drilled with holes slightly larger than the diameter of the fasteners, the material will buckle around the drill holes. This buckling is unsightly and causes stress on the plastic sheeting. Polycarbonate material is known for its virtually indestructible nature; however, it is vulnerable to stress caused by improper handling or installation. Pre-drill to avoid any of these issues.

How Cold Affects Drilling

Pre-drilling is highly important, especially with winter months. The cold temperatures cause the polycarbonate sheeting to contract. If you do not pre-drill, the stress of the contraction will cause spider cracks that stem from each drill hole and destroy the polycarbonate sheeting. Pre-drilling allows for space around the fastener so that the plastic can expand and contract without stress or issue.

How Humidity Affects Drilling

Polycarbonate is hydroscopic, which means it can absorb moisture from the atmosphere. In an ideal condition, the plastic sheeting can absorb and release moisture without any issues. Problems arise when fastener holes are not pre-drilled and there is not any wiggle room for the plastic to fluctuate and breathe. If the plastic cannot properly release the moisture, the stress will cause cracks and lead to the problematic accumulation of dirt, mold, mildew, and pests. Additionally, the accumulation of moisture and eventual cracks can lead to leaks and other major issues.

Benefits of Pre-Drilling

When you read plastic installation guides, you will see “pre-drilling” mentioned repeatedly because it offers important benefits to the construction process and project. 

Pre-Drilling Prevents Cracks

If you do not pre drill plastic, and instead drill the fastener directly into the material, it is highly likely that you will damage the integrity of the material. Spider cracks will almost certainly develop and these tiny fissures will be disastrous for your project. Pre-drilling required to properly pierce plastic and nearly eliminate the risk of problematic spider cracks. 

Pre-Drilling Helps Create Holes for Screws

Pre-drilling is a convenient way to create holes for the fasteners or screws that you will use to attach the sheeting to the support. If you use other methods to create holes, you can potentially damage the surface of the plastic. Pre-drilling is the easiest and most effective solution. 

Pre-Drilling Helps Plastic Attach to the Support

The ultimate goal for installation is a secure and proper attachment. When you properly pre-drill holes, you allow the plastic to easily and smoothly attach to the final support and ensure that your project can reach its intended potential. 

Pre-Drilling Saves Money

Pre-drilling is beneficial because it allows you to optimally utilize a highly beneficial building material. Polycarbonate and plastic sheets have high performance value, are durable when properly installed and handled, and are relatively inexpensive. When you pre-drill plastics, you reduce operational costs and ensure they can maximize their potential value for your use application. 

Onduline has been manufacturing roofing materials and cladding systems for over 75 years.  In North America, the Tuftex® brand provides quality corrugated plastics for a variety of agricultural and professional plastics applications. For more professional resources and high-quality materials, visit the Onduline site today.