Characteristics of uPVC Fastener Screws:

uPVC screws are specially designed to address these challenges:

1. Thread Design:

   • Fine Thread / Self-Tapping: They typically have a finer, often “hi-low” (double) thread or a more aggressive self-tapping thread design. This allows them to create their own thread in the uPVC material cleanly and securely without splintering or cracking it.

   • Sharp Point: They often have a sharp, self-drilling point, sometimes with a “4CUT™” point or similar design, which helps displace the uPVC material without cracking and often eliminates the need for pre-drilling (though for critical structural fixings, pre-drilling is still recommended).

2. Material and Coating:

   • Corrosion Resistance: This is paramount. They are usually made from stainless steel (various grades like 304 or 410) or carbon steel with advanced corrosion-resistant coatings (e.g., zinc plating, dichromate, or specialized coatings like “Atlantis” or “HCR-X™”). This prevents rust staining on the uPVC and ensures longevity.

   • Hardened Steel: For strength and durability.

3. Head Types:

   • Countersunk Head: Most common for a flush, neat finish when fastening hardware or joining uPVC profiles.

   • Wafer Head / Pan Head: For applications requiring more surface area under the head for clamping force.

   • Drive Types: Phillips, PoziDriv, or Torx (star drive) are common, with Torx often preferred for better torque transmission and reduced cam-out.

4. Specific Applications within uPVC:

   • Reinforcement Screws (PVC-40): Used to fix steel reinforcements inside the uPVC profiles. These are often self-drilling screws.

   • Hardware Fixing Screws (PVC-10, PVC-20): For attaching hardware like hinges, locks, and keeps to the uPVC profile.

   • Frame Fixing Screws (PVC-70): Used to directly fix the uPVC window/door frame to the masonry or concrete wall. These are often much longer and can sometimes be nylon frame fixing screws or concrete screws.

   • Baypole Screws: Self-drilling screws for joining uPVC window frames, particularly at bay window angles.

   • Cill Screws: For attaching the uPVC cill (external sill) to the main window frame.