Concrete screws
Concrete Screws – Overview
Concrete screws are an efficient and easy-to-use solution for fastening directly into concrete, without additional fasteners such as plugs or chemical anchors. They mechanically bite into the concrete and are used in both construction and installation work.
Screw and Head Types
1. Hex Washer Head
Use: Heavy-duty fastening (e.g. steel profiles, brackets, rails)
Installation: The hex head makes torque transfer easier
Washer flange: Distributes clamping force → better load capacity
Coatings: Commonly multilayer zinc coatings, such as:
Zintek, Ruspert, Delta Protekt, up to >1000 h salt spray test
Availability: Sormat BSS-H, Index FTP-F series
2. Flat Head Torx
Use: Installations where the head must not remain visible (e.g. fastening wood or board structures to concrete)
Torx drive: Improves torque transfer and reduces slipping
ETA-certified versions: Available from Sormat and Index
E.g. Sormat BSU-TX, Index FTP-FH-T
3. Pan Head and Pan Head with Washer Flange Torx
Use: Surface-mounted fastenings where appearance or even clamping is important
Flanged pan head: Better clamping without a washer
Torx drive: Efficient and secure installation
Suitable for lighter or medium-load fastenings
Coatings and Protection
Concrete screws are often exposed to demanding conditions (outdoors, moisture, industrial environments). The most common coatings are:
Coating - Corrosion protection (salt spray test) - Notes
Electro-galvanized zinc - 48–120 h - Indoor use only
Ruspert - 500–1000 h - Good for both indoor and outdoor use
Delta Protekt - 1000+ h - Extremely durable protection, thin film, environmentally friendly
Zintek - Over 500 h - Often used in Sormat products
Acid-resistant stainless steel (A4) - Natural protection - For chemically demanding environments
Sormat vs. Index – Concrete Screw Series
Sormat (Finland)
BSS series: Hex head, flanged (often Zintek coating)
BSU-TX: Flat head, Torx
BSP-TX: Pan head, Torx
ETA approvals: Available for many models
Index Fixing Systems (Spain)
FTP-F: Hex washer head
FTP-FH-T: Flat head, Torx
FTP-FT-T: Pan head, Torx
Special coatings: Ruspert / Delta Protekt
ETA approval: Available for several FTP models
Installation Notes
Drilling: Pre-drilling is required for concrete, and the hole must match the screw diameter (e.g. a Ø10 mm screw → a Ø10 mm hole). The diameter shown in the product name indicates the drill bit size to be used. This size does not include the thread height, meaning the actual screw diameter is larger than the stated diameter/drill size. This must be taken into account when planning the material to be fastened, so that the concrete screw can pass through the hole made in the part!
Anchoring depth: Important for load capacity
Torque limits: Do not exceed the screw’s maximum torque → use a torque wrench
Operating temperature and fire resistance: Tested in certain ETA-approved models