Concrete anchors and rivet nuts: drop-in, sleeve and S-type anchors compared, with sizes

How drop-in, sleeve (type T and F) and S-type expansion anchors differ, which one to choose for concrete and solid masonry, the sizes and piece weights we supply, and when a rivet nut is the right fastener instead.

Updated October 18, 2026

A mechanical expansion anchor holds in concrete by pressing a sleeve or wedge against the wall of a drilled hole. The anchors on this page are commercial carbon-steel anchors, zinc plated, for medium-duty fixings in concrete and solid masonry. They are not ETA-assessed anchors with published design resistances, so the safe load of a fixing depends on the concrete, the edge distance and the installation, and should be set by the designer of the fixing.

The four types at a glance

Drop-in anchors

A drop-in anchor is an internally threaded sleeve with an expansion cone inside. After the hole is drilled and cleaned, the anchor is tapped in flush and a setting punch drives the cone down, which spreads the sleeve. A metric bolt or threaded rod then screws into the anchor. Because nothing protrudes, the slab can be prepared before the fixture arrives. An anchor that has not been set with the punch has no holding capacity.

Sleeve anchors, type T and type F

A sleeve anchor is a bolt with a slotted sleeve around it. Tightening the nut pulls a cone into the sleeve, which expands against the hole. Type T is the through-fixing pattern: the fixture is placed, the hole is drilled through it, and the complete anchor goes through the fixture into the base material in one pass. Type F has a different sleeve layout for details where the sleeve is set first and the fixture is secured afterwards. In both cases the hole diameter matches the sleeve, not the bolt.

S-type anchors

The S-type anchor is a through-fixing expansion anchor widely used for plant installation and building services. Like a type T sleeve anchor it goes through the fixture and expands as it is tightened. It is the usual choice for frames, guards, pipe supports and holding machines down on a concrete slab.

Which anchor to choose

• Thread needed in the slab, fixture later — drop-in anchor, used with a bolt or threaded rod.
• Fixture already in place, one-step installation — sleeve anchor type T or S-type anchor.
• Solid masonry — sleeve anchors are listed for concrete and solid masonry; none of these anchors is meant for hollow block.
• High or safety-critical loads — use an anchor with a published design resistance (an ETA-assessed mechanical or chemical system) and a calculated design.

Installation basics

• Drill the hole to the diameter and depth the anchor requires, and clean out the drilling dust before setting it. Dust left in the hole reduces the holding force.
• Keep to the minimum edge distance, spacing between anchors and slab thickness for the size you use. Anchors set too close to an edge can split the concrete.
• Tighten to the specified torque. Over-tightening can damage the anchor or the concrete; under-tightening leaves the sleeve unexpanded.
• Zinc plating suits dry indoor use. For outdoor or damp locations specify a stainless or hot-dip galvanized anchor.

Rivet nuts: a thread in thin sheet and tube

A rivet nut is not a concrete anchor. It puts a reusable metric thread into material too thin to tap — sheet, tube walls and cabinets. The nut is placed in a hole and a rivet-nut tool pulls the body so that it folds behind the sheet, all from one side. Ours are zinc-plated carbon steel with a cylinder body, flat head and open end, M5 to M10. The grip range must suit the sheet thickness, so state the material thickness when you order.

Frequently asked questions

Send your list of anchor types, sizes and quantities in a quote request. Bolts, threaded rod and washers can be quoted in the same enquiry — see the bolt grades and sizes guide.