How to ensure compatibility between foundation screws and STRUCTURAL® aluminum joists?

The Cobrafastener® SPIRAL® foundation screw are designed to be perfectly compatible with the STRUCTURAL® aluminum joists, while guaranteeing a durable, safe and corrosion-free installation.

The system integrates a insulating plastic wedge specially developed to avoid any contact between galvanized steel and aluminum, as well as calculation notes validated for different uses (residential or commercial).

1. Secure fixing without galvanic corrosion

When a galvanized steel screw comes into direct contact with aluminum, a electrochemical reaction can occur over time, leading to a risk of galvanic corrosion.

To avoid this, Cobrafastener® has developed a insulating plastic wedge which is inserted between:

• the galvanized foundation screw head,
• and the STRUCTURAL® aluminum joist.

This part plays a dual role:

• she prevents direct metal-to-metal contact, eliminating any risk of corrosion,
• she centers and stabilizes the joist on the screw head, ensuring a rigid and durable hold.

Result: a healthy structure, without oxidation, meeting the sustainability requirements of the STRUCTURAL® concept.

💡 Pro tip: the insulating wedge is supplied separately, depending on the SPIRAL® screw head

2.Structural compatibility validated by technical calculations

Each combination foundation screw + joist STRUCTURAL® was the subject of calculation notes and load tables available in the technical file for the STRUCTURAL® concept.

These documents specify:

• the maximum centers between screws depending on the joist section (40×60, 80×60, 120×60 mm),
• the admissible loads in residential and commercial use,
• and the anchoring conditions to be respected depending on the type of soil and the height to be taken.

Some benchmarks: