Concrete Expansion Anchor Bolts M6–M20, Extra Long Masonry Wall Screws – Iron Blue White Zinc / Iron-colour Zinc

Generally, the bolt length should equal the fixture thickness plus the minimum embedment depth into the base material. For concrete, a minimum embedment of typically 25–40mm is recommended depending on the diameter. For example, if your bracket is 20mm (≈3/4") thick and you need 30mm (≈1-3/16") of embedment, choose at least a 50mm (≈2") bolt. Always add a safety margin and check the load requirements for your specific application.

Load capacity depends on the bolt diameter, embedment depth, and the compressive strength of the base material. Larger diameters (M12–M20) in solid concrete generally support significantly higher loads than smaller sizes (M6–M8). For structural or safety-critical applications, always refer to engineering load tables or consult a qualified professional. Do not rely on general estimates for overhead or life-safety anchoring.

These bolts feature a zinc plating finish that provides a basic level of corrosion resistance suitable for dry indoor and sheltered outdoor use. For prolonged exposure to rain, salt air, or standing water, additional sealing or stainless steel alternatives are generally recommended. The Iron Blue White Zinc finish typically offers slightly more visible corrosion protection than the Iron-colour Zinc in comparable conditions.

These bolts follow the standard ISO metric coarse thread specification, which is the most widely used standard in construction hardware worldwide. M6, M8, M10, M12, M14, M16, M18, and M20 designations refer to the nominal outer thread diameter in millimeters. Any standard metric nut or washer of the matching size should fit without modification.

Iron Blue White Zinc offers a bright, silver-blue appearance and is a good general-purpose choice for most indoor fastening applications where a clean look is preferred. Iron-colour Zinc has a darker, more matte finish that blends in better with raw concrete or dark-painted surfaces. Both finishes provide comparable zinc corrosion protection — the choice is primarily aesthetic.

Yes. These expansion anchor bolts are designed for use in solid masonry materials including poured concrete, solid brick, and dense concrete block. They are generally not recommended for hollow block, aerated concrete (AAC/Aircrete), or soft brick without consulting the appropriate anchor type for those substrates. When in doubt, test a single anchor before committing to a full installation.

The required hole diameter typically matches the bolt's nominal diameter — for example, an M8 expansion bolt generally requires an 8mm masonry drill bit. Always use a hammer drill (rotary hammer for larger sizes) with a carbide-tipped masonry bit for best results in concrete or brick. Clean the hole of dust before inserting the anchor to ensure proper expansion and grip.