Step 1: know the base material
- Concrete: the most common base. Decide whether it may be cracked (tension zones of beams and slabs, where hairline cracks open under load) or non-cracked. Anchors approved for cracked concrete are needed in most structural and safety-related fixings.
- Solid masonry (brick, solid block): lower strength, so loads are smaller and expansion forces must be gentle.
- Hollow block and perforated brick: expansion anchors grip poorly; use injection anchors with mesh sleeves or long frame fixings.
- Old or unknown concrete: test it. Site pull-out tests show what the actual material can carry.
Step 2: know the load
Note the size and direction of the load (tension, shear or both), whether it is static or dynamic, and whether seismic or fire performance is needed. Sustained tension on overhead fixings and safety-critical items need approved anchors and a design calculation.
Step 3: choose the anchor type
| Type | Works by | Best for |
|---|---|---|
| Wedge / bolt anchor | Expansion clip at the tip, set by torque | Steel base plates, brackets and machinery in concrete; push-through installation |
| Sleeve anchor | Full-length sleeve expands | Medium loads in concrete and solid masonry |
| Drop-in anchor | Internal cone, set with a setting tool; flush | Threaded rod hangers for pipes, ducts and cable trays in slabs |
| Frame fixing | Long plastic plug with screw | Window and door frames, light fixings in masonry |
| Chemical (bonded) anchor | Resin bonds a rod to the hole wall; no expansion force | High loads, close edge and spacing distances, hollow materials with sleeves, post-installed rebar |
Step 4: check edges, spacing and embedment
Every anchor needs a minimum edge distance, spacing and member thickness, and its capacity rises with embedment depth. Too close to an edge, and the concrete breaks out before the anchor reaches its load. Bonded anchors, which put no expansion force into the concrete, usually allow closer edges and spacing than expansion anchors.
Step 5: look for approvals
For structural and safety-related fixings, use anchors with a European Technical Assessment (ETA) for the use you need (cracked concrete, seismic category, fire), designed to EN 1992-4. The ETA gives the tested capacities, drill sizes, torques and minimum distances. Corrosion matters too: use zinc-plated anchors indoors and dry, hot-dip galvanised or A4 stainless anchors outdoors and in damp or coastal areas.
Step 6: install it correctly
- Drill the specified diameter and depth, normally with a hammer drill. Use diamond core drilling only where the approval allows it.
- Clean the hole: blow, brush, blow. Dust left in the hole can cut the capacity of a chemical anchor dramatically.
- Set the anchor: torque expansion anchors to the stated value with a calibrated wrench; for chemical anchors, inject from the bottom of the hole and respect the gel and cure times for the temperature.
- Verify with site pull-out tests where the base material is uncertain or the project specification asks for it.
Figures are typical values for guidance. For design, inspection and purchase, always follow the current edition of the standard on your drawing.