Stainless Steel Masonry Expansion Bolts – M6 M8 M10 M12 M14 M16 M20 Concrete Wall Anchor Screws

A general rule: the bolt should penetrate the base material (concrete, brick, or stone) by at least 5–10 times the bolt diameter. For example, an M8 bolt typically needs at least 40–80mm of embedment depth. Add the thickness of the fixture to get your total required length. Available lengths range from 50mm (≈2") to 250mm (≈9.8"). When in doubt, go longer — you can always use a washer to take up slack, but you cannot extend a bolt that is too short.

Load capacity depends on bolt diameter, embedment depth, and the compressive strength of the base material. Generally, larger diameters and deeper embedment yield higher pull-out and shear resistance. For structural or safety-critical applications, consult a structural engineer and refer to manufacturer load tables for your specific size. Do not use these anchors in cracked concrete without verifying suitability.

Yes. A2 stainless steel (304 grade) is suitable for most outdoor and mildly corrosive environments, including general exterior construction and landscaping. A4 stainless steel (316 grade) offers superior resistance to chlorides and salt spray, making it the preferred choice for coastal, marine, swimming pool surrounds, or chemically aggressive industrial environments.

These bolts use standard ISO metric coarse-pitch threads (M6 through M20), which is the most common standard for masonry anchors worldwide. They are compatible with standard metric hex nuts, flat washers, spring washers, and threaded rod couplers of the same nominal diameter.

Typically, you drill a hole matching the bolt's nominal diameter using a carbide-tipped masonry bit in a hammer drill. For example, an M8 expansion bolt generally requires an 8mm masonry bit. Hole depth should equal the required embedment depth plus a small clearance for dust. Always blow out the hole with compressed air before inserting the anchor.

A2 (304 stainless steel) is a general-purpose grade with good corrosion resistance for most indoor and outdoor applications — suitable for garden walls, interior concrete, and standard exterior construction. A4 (316 stainless steel) adds molybdenum for enhanced resistance to chlorides, salt water, and industrial chemicals. Choose A4 for marine, coastal, pool, or food-processing environments where A2 may eventually show surface staining or pitting.

These expansion bolts feature a hex head and are tightened with a standard metric socket wrench or open-end spanner. The anchor is generally considered set when the bolt reaches the specified installation torque for its diameter — consult the torque table for your size. Visually, the fixture should be pulled flush against the surface with no movement. Avoid over-torquing, which can crack the base material or strip the anchor sleeve.