Concrete & Masonry Anchor Guide: Wedge, Sleeve, Drop-In, Chemical & Plasterboard Anchors

The wrong concrete anchor is one of the most expensive cheap mistakes in construction. A $4 chemical anchor in the wrong place can lead to a $40,000 remedial job; the right anchor for the wrong substrate fails the same way; the right anchor with the wrong drill bit, hole depth or installation technique fails before it gets loaded. This guide answers the questions that AU practitioners actually ask on Bunnings Workshop, Whirlpool Forums and Homeone — what anchor for what job, what drill bit size for what anchor, mechanical vs chemical, AS 5216:2018 compliance, why your anchor keeps pulling out, and what's actually different between Hobson Clawbolt Pro, Bremick Screw Anchor, Inox World 316 stainless, and the Ramset trademarks (Dynabolt®, Chemset®, Trubolt®, Ankascrew®) that have become the generic names for the categories.

🔧 Need the drill bit size right now? Jump straight to the Drill Bit Size Reference Table — every common anchor type and size, with the matching masonry drill bit and minimum hole depth.

Honest scope: AIMS stocks 40+ concrete and masonry anchor products across our anchors collection, drop-in anchors collection and concrete screws collection — Hobson Clawbolt Pro wedge anchors (AS 5216-compliant, ETA Option 7, fire-rated), Hobson Xbolt masonry screws, Hobson Drop-In Pro anchors, sleeve anchors, chemical anchor stud kits, plus Bremick, Inox World 316 stainless, and Champion manifold studs. AIMS does NOT sell Ramset — the Dynabolt®, Chemset®, Trubolt®, Ankascrew® and ChemSet® names are all Ramset trademarks (ramset.com.au). We sell equivalents — different brands, same anchor categories. We also don't stock Hilti, Powers, Allfasteners, Wurth or Simpson Strong-Tie — flagged source-on-request via our supplier network.

Quick Jump

• Drill Bit Size Reference Table — every anchor type and size
• Six Anchor Families — Decision Matrix
• The Trademark Reality — Dynabolt, Chemset, Trubolt, Ankascrew
• Mechanical Anchors (Wedge, Sleeve, Drop-In)
• Chemical Anchors (Cartridge + Stud)
• Masonry Screws (Hobson Xbolt + Bremick)
• Plasterboard & Hollow Wall Anchors
• AS 5216:2018 Compliance + ETA Options
• Hammer Drill vs Rotary Hammer
• Installation Procedures
• Failure Modes — Why Anchors Pull Out
• Frequently Asked Questions

Six Anchor Families — Decision Matrix

Every concrete and masonry anchor falls into one of six families. The single biggest mistake is using a family designed for solid concrete in hollow brick (or vice versa). Match the anchor to the substrate first, then size and finish second.

The cardinal rule: if you can't tell whether your substrate is hollow or solid, drill a small test hole first. Hollow brick and core-filled block look identical from the outside; the drill bit tells the truth in 30 seconds. Hitting an unexpected cavity halfway through tightening is the most common cause of "the anchor turns when I tighten it" forum posts on Bunnings Workshop and Whirlpool.

Drill Bit Size Reference Table — Every Anchor, Every Size

The single most-asked question on every AU concrete anchor forum: "What size masonry drill bit do I need?" Use this table. All measurements are nominal AU industry standards; always cross-check your specific product packaging — manufacturers publish exact specifications and tolerances on the label.

Wedge Anchors (Hobson Clawbolt Pro, equivalent to Ramset Trubolt®)

Wedge anchor rule: drill bit diameter equals nominal anchor diameter exactly. Don't go oversize — the wedge needs the close hole fit to expand against.

Sleeve Anchors (Hobson Flush Head Sleeve)

Sleeve anchor rule: drill bit equals the sleeve outer diameter (which is sometimes larger than the stated thread size — check the product label). The sleeve must enter the hole flush; oversized hole = no expansion = no hold.

Drop-In Anchors (Hobson Drop-In Pro)

Drop-in anchor rule: drill bit is LARGER than the thread size (M8 thread → 10mm bit, etc.). You also need the matching setting tool ($10.83) — without it the internal plug doesn't seat properly and the anchor fails. Hole depth is minimal (just anchor length) because drop-ins are flush-mount.

Chemical Anchor Studs (Hobson Grade 5.8 Stud Kit, Inox 316 Stainless Stud)

Chemical anchor rule: drill bit is 2-4mm larger than stud diameter — the gap is filled with resin. Hole depth includes embedment plus extra space for resin reservoir. Hollow substrates require a sleeve insert (anchor sleeve) in the hole to contain resin within the cavity.

Masonry Screws (Hobson Xbolt)

Masonry screw rule: hole tolerance is critical. Each Hobson Xbolt size has a specific drill diameter on the packaging — using a bit a single millimetre too large reduces hold by 30-50%. Drill clean and to-depth; the special thread does the rest.

The Trademark Reality — Dynabolt, Chemset, Trubolt, Ankascrew

Australian tradies, hardware staff and engineering specifications use four names so often that most people forget they're proprietary trademarks owned by Ramset Australia:

What this means practically: if your engineer's spec calls for "Trubolt M12 fire-rated zinc plated", you can substitute the Hobson Clawbolt Pro M12 fire-rated zinc plated provided the engineer signs off on the equivalence (both are AS 5216-compliant ETA Option 7 wedge anchors with the same fundamental geometry and load capacity range). If the spec specifically says "Ramset Trubolt" rather than just "wedge anchor", talk to the engineer first — sometimes the spec is calling out a specific tested system for a particular load case. For most general work, the AS 5216 + ETA approval is the engineering-relevant credential, not the brand name.

AIMS doesn't sell Ramset products. Our supplier relationships are with Hobson, Bremick, Inox World, Champion and other AU industrial brands. When customers ask for "Dynabolt" we sell them the sleeve or wedge equivalent for their application; when they ask for "Chemset" we sell them a chemical anchor stud kit with matching resin cartridge. The categories are universal across brands; the trademarks aren't.

Mechanical Anchors — Wedge, Sleeve, Drop-In

Wedge Anchors — How They Work and When to Use Them

A wedge anchor is a threaded stud with a cone-shaped end and a one-piece expansion sleeve (the "clip"). When you tighten the nut, the cone pulls up into the sleeve, splaying it outward against the concrete wall and locking the anchor in place. Wedge anchors generate the highest mechanical hold of any single-pour-concrete mechanical anchor.

Wedge anchors require solid concrete. Hollow brick will not provide enough surrounding material for the expansion sleeve to wedge against; the anchor will spin in the hole when you try to tighten. The Hobson Clawbolt Pro range (sizes M8 through M20) is fire-rated C1/C2 zinc plated and ETA Option 7 approved per AS 5216:2018 — the AU industrial standard for engineered concrete anchorage.

AIMS stocks: Clawbolt Pro C1 & C2 Fire Rated Zinc Plated ($34.94+), Clawbolt Pro C1 Fire Rated Zinc Plated ($46.58+), Clawbolt Pro Fire Rated Zinc Plated ($60.56+).

Sleeve Anchors — How They Work and When to Use Them

A sleeve anchor is a threaded bolt or stud inside a full-length expansion sleeve. Tightening the nut compresses the sleeve along its entire length against the concrete or brick wall. Sleeve anchors are more forgiving than wedge anchors in irregular or weaker substrates because the holding force is distributed along the full sleeve length rather than concentrated at a wedge cone.

Sleeve anchors are the standard choice for solid brick, concrete block, and medium-strength concrete. The flush-head variant (zinc yellow passivate) sits flush with the workpiece — used for cabinetry, brackets, and machinery mounting where a protruding head would interfere.

AIMS stocks: Flush Head Sleeve Anchor Zinc Yellow Passivate ($11.65+, 10mm and 12mm body sizes), Countersunk Head Sleeve Anchor 316 Stainless ($88.42), Hex Flange Nut Sleeve Anchor 316 Stainless ($60.56).

Drop-In Anchors — How They Work and When to Use Them

A drop-in anchor is a hollow cylindrical sleeve with an internal cone. The anchor is set into the hole, the matching setting tool drives the internal cone downward, and the sleeve expands outward to grip the concrete. Once set, the internal female thread accepts a bolt or threaded rod.

Drop-in anchors win in two scenarios: flush installations where no anchor protrudes above the surface until the bolt is fitted (clean ceiling fixings, retrofittable machinery mounts), and overhead concrete work where the anchor stays in place while you position the load (vs. a wedge anchor where the stud hangs down before you can attach the load). They require dense solid concrete and the correct matching setting tool ($2.43).

AIMS stocks: Metric Drop-in Anchor Zinc Yellow (M6-M20, $10.18+), Drop-In Pro Anchor Fire Rated (M8-M12, $22.05+, ETA Option 7), Drop-In Pro With Lip Fire Rated ($25.04+), Knurled Body Drop-In With Lip Zinc Yellow ($14.27+), Drop-in Anchor 316 Stainless ($85.89), Inox World Drop In 316 Stainless ($74.28), plus setting tools.

Chemical Anchors — Cartridge Resin + Stud

A chemical anchor is a two-part epoxy or vinylester resin pumped from a cartridge into a clean drilled hole; a threaded stud is then pushed into the resin and held perpendicular until the resin cures. Once cured, the stud is bonded to the substrate along its full embedment depth.

Chemical anchors are the go-to solution for hollow brick, hollow block, edge-distance-critical work, cracked concrete, and heavy loads. Forum-validated consensus from Bunnings Workshop, Homeone and Whirlpool: when mechanical anchors fail in hollow material, chemical anchors hold. The trade-off is cure time — you can't load a chemical anchor instantly.

Chemical Anchor Cure Time by Ambient Temperature

Gel time = time before resin hardens enough that further adjustment cracks the bond. Full cure = time before applying rated load. Read the specific cartridge instructions — vinylester resins cure faster than epoxy; some have different gel/cure curves.

AIMS stocks: Metric Stud Chemical Anchor Kit Grade 5.8 Zinc Yellow (M8-M24, $4.19+) and Inox World Stud Anchor 316 Stainless ($51.14). Resin cartridges and dispensing guns are sourced via supplier network — contact the trade team for matched-system pricing.

Masonry Screws — Hobson Xbolt + Bremick Screw Anchor

A masonry screw is a self-threading anchor that cuts its own thread into a pre-drilled hole as it's driven. The thread profile is engineered specifically for masonry — wider, sharper, deeper than a regular wood or metal screw thread. Hobson Xbolt (the equivalent of the Ramset Ankascrew® trademark category) uses a unique geometry that produces strong pull-out resistance in concrete, solid brick and dense block.

Masonry screws have two practical advantages over expansion anchors: they're removable and the hole is reusable (re-drive a new screw of the same size into the existing hole), and they generate zero expansion stress in the substrate — useful for working close to edges or in older concrete where wedge anchor expansion forces would risk cracking.

AIMS stocks the full Hobson Xbolt range: Xbolt Hex Flange Zinc Yellow ($32.60+, M5-M8+), Xbolt Hex Flange Mechanical Galvanised ($21.14+), Xbolt Countersunk Mechanical Gal ($40.87+), Xbolt Countersunk Zinc Yellow ($26.78+), Xbolt Torx Drive Dome Head MG ($25.74+), Xbolt Eye Anchor Zinc Yellow ($87.34), Xbolt Coupler Screw Mechanical Galvanised ($118.87+), and TX-CON Hex Slotted Anchor Screw R1000 Coating ($11.64).

AIMS also stocks Bremick screw anchors: Bremick Screw Anchor Hex Zinc Plated ($33.28+) and Bremick Screw Anchor Hex Galvanised ($45.35+).

Plasterboard & Hollow Wall Anchors

Plasterboard (gyprock) and hollow doors don't have enough mass to grip a concrete anchor. The category of "hollow wall anchors" instead grips the back face of the plasterboard sheet through one of three mechanisms: toggle wings, expanded sleeve (molly), or plastic butterfly that opens behind the wall.

AIMS stocks: Hollow Wall Anchor Carbon Steel Zinc Plated ($12.97, molly-style 10-25 kg), Plasterboard Wall Plug #8 Nylon Box of 100 ($9.95), Universal Wall Plug Tapered Point Nylon ($14.16), Round Head Nail-In Anchor Nylon Body 304 SS Pin ($10.48).

Forum-validated reality from FineWoodworking + A Butterfly House + Bunnings Workshop: a toggle bolt holds 2-3× what a plastic wall plug holds, but the trade-off is that toggles can't be removed cleanly (the wings fall into the cavity). For anything you might ever take down again, use a molly or a plastic plug. For anything that has to hold heavy gear permanently, use a toggle.

AS 5216:2018 + ETA Options — The Engineering Compliance Reality

AS 5216:2018 (the AU standard, now also published as 5216:2021) is the design and qualification standard for post-installed mechanical and chemical anchors in concrete. The National Construction Code (NCC) references AS 5216 for structural anchorage applications. For most domestic and light-commercial work the standard isn't strictly mandatory, but for any anchor in a structural load path, fire-rated assembly, or engineered specification, AS 5216 compliance is non-negotiable.

Cracked vs Uncracked Concrete

AS 5216 distinguishes between cracked concrete (any concrete whose tensile strength may be exceeded during service, producing cracks up to 0.3mm wide passing through the anchor plane) and uncracked concrete (concrete that remains in compression throughout service). The strength reduction is material — design factor k9 is 1.7 for cracked concrete vs 2.4 for uncracked. In real terms, an anchor in cracked concrete carries roughly 30% less load than the same anchor in uncracked concrete.

How do you know which you have? Engineering review of the structural load case. If the concrete element is in tension under any service load (slab soffits, retaining wall faces, bridge structures, anchorage zones near edges), assume cracked. If it's continuously in compression (column bases under axial load, ground slab on grade), uncracked may apply.

ETA Option 1 vs Option 7

The European Technical Assessment (ETA) prequalification system has 12 different "Options" describing the test scenarios an anchor has been qualified against. AS 5216 Appendix B maps these to AU equivalents. The two most common practically:

• ETA Option 1 — qualified for cracked AND uncracked concrete. Use this option when the structural load case requires cracked-concrete capability.
• ETA Option 7 — qualified for uncracked concrete only. Use for compression-loaded or non-structural anchorage where cracking is precluded.

The Hobson Clawbolt Pro range carries ETA Option 7 — appropriate for general fastening, machinery mounting, and most commercial fit-out work in uncracked concrete. For structural anchorage in tension zones, engineers typically specify ETA Option 1 anchors — these are available via specialty supplier (Hilti, Powers, Wurth) and AIMS sources on request.

Fire Ratings — C1 vs C2

Fire-rated anchors are tested per EN 1992-4 / EOTA TR 020 for retention of load capacity under fire exposure. C1 rating is for use where the fastening is not exposed to fire on multiple sides; C2 rating allows for fire exposure on multiple sides simultaneously. The Hobson Clawbolt Pro C1 & C2 Fire Rated is qualified to both — suitable for fire-rated wall and ceiling assemblies per NCC Section C requirements.

Hammer Drill vs Rotary Hammer — Use the Right Tool

The single most common AU forum complaint pattern: "I tried to drill into the concrete slab with my hammer drill and it took forever and the bit went blunt and I gave up." From Whirlpool Forums and Bunnings Workshop direct quotes: "Regular hammer drills are largely a waste of time using on concrete — you need a rotary hammer."

Hard Aggregate + Reo Bar — When the Drill Stops

Two AU-specific problems forum users hit repeatedly:

1. Hard aggregate — older NSW concrete in particular often contains basalt or quartz aggregate that's "as hard as the hobs of hell" (direct quote from Whirlpool Forums, Sydney user). Modern carbide-tipped SDS bits handle it but progress is slow. Switching off the hammer action for 10 seconds (rotation only) sometimes helps break through a stubborn stone, then re-engage hammer.
2. Hitting reo bar — reinforcing bar in slab + tilt-up panel construction will stop any masonry bit dead. The drill body keeps spinning, the bit doesn't, and the operator's wrist takes the recoil torque. Wrist injuries from this are documented. If your drill suddenly slows and starts kicking, stop immediately. Reposition the hole 50mm to one side and retry. Drilling through reo bar requires a rotary hammer with multi-material capability or a diamond core drill — neither of which is the right tool for an anchor hole.

If you're working on structural concrete and uncertain about reo locations, a rebar locator (or just a magnet sliding across the surface — the metallic field gives away most rebar within 50mm of the surface) is a 30-second insurance step.

Installation Procedures by Anchor Type

Wedge Anchor (Hobson Clawbolt Pro)

1. Mark the hole location. Confirm substrate is solid concrete with a 5mm test hole if uncertain.
2. Fit the correct masonry drill bit (anchor diameter — see drill size table). Use a rotary hammer.
3. Drill to the correct depth (embedment + 15mm dust allowance — see table). Mark the bit with tape to depth-stop accurately.
4. Blow the hole clean (hand pump or compressed air). Brush with a wire brush. Blow again. This step matters more than people think.
5. Insert the anchor through the fixture into the hole. Tap with a hammer if needed to seat the anchor fully — the threaded end should protrude above the workpiece by the bolt thread length plus washer plus nut.
6. Hand-tighten the nut until snug.
7. Torque the nut to the manufacturer's specification using a calibrated torque wrench. Over-torque cracks the concrete around the anchor; under-torque leaves the anchor loose. The Hobson Clawbolt Pro torque values are printed on the box.

Sleeve Anchor (Hobson Flush Head Sleeve)

1. Drill the correct-diameter hole to depth (see drill size table).
2. Clean the hole — blow + brush + blow.
3. Insert the sleeve anchor through the fixture into the hole. The sleeve should slide in cleanly. If it binds, the hole is undersize or has loose debris — re-drill or re-clean.
4. Hand-tighten the nut until snug, then torque to specification.

Drop-In Anchor (Hobson Drop-In Pro)

1. Drill the correct-diameter hole to exactly the anchor depth — drop-ins are flush-mount, so hole depth = anchor length.
2. Clean the hole thoroughly.
3. Insert the drop-in anchor with the lip flush to the concrete surface.
4. Position the matching setting tool over the anchor. Strike the tool with a hammer until the setting tool collar hits the anchor flange — this drives the internal cone down and expands the anchor.
5. Remove the setting tool. The anchor is now set and ready to accept a threaded bolt.
6. Thread the bolt or threaded rod into the anchor; tighten to specification.

Chemical Anchor (Hobson Grade 5.8 Stud Kit)

1. Drill the correct hole (2-4mm larger than stud diameter — see drill size table) to the correct depth.
2. Clean the hole obsessively — blow 3 times, brush 3 times with the correct nylon brush, blow 3 more times. A dusty hole = 50% strength loss.
3. If the substrate is hollow, insert the matching anchor sleeve to contain the resin in the cavity zone.
4. Fit the mixing nozzle to the cartridge. Discharge the first 100mm of resin to waste (this is incompletely mixed material).
5. Inject resin from the bottom of the hole upward, filling approximately 2/3 of the hole volume. Withdraw the nozzle as you fill to avoid trapping air.
6. Push the threaded stud into the hole while rotating slightly. The resin should rise around the stud and expel slightly at the surface — that's correct fill.
7. Position the stud perpendicular and brace it (a paper template, jig, or magnetic level). Do not disturb it during cure.
8. Wait the full cure time (see cure-time table) before applying any load.

Masonry Screw (Hobson Xbolt)

1. Drill the correct-diameter hole (specific to each Xbolt size — printed on the box) to depth.
2. Clean the hole.
3. Drive the masonry screw using an impact driver or socket wrench. The Xbolt's special thread cuts into the masonry as it advances.
4. Stop at correct embedment / when the screw is firmly seated. Do not over-drive (strips the substrate thread).

Failure Modes — Why Your Anchor Keeps Pulling Out

From Bunnings Workshop, Whirlpool Forums, Eng-Tips and AEFAC training material, anchor failures fall into three engineering categories plus a fourth (installation error) that's by far the most common in practice:

Edge Distance + Spacing Rules

Mechanical anchors generate expansion force that pushes outward on the surrounding concrete. Too close to a free edge or another anchor and the concrete fails before the anchor does. AS 5216 minimum spacing rules (rule of thumb):

• Edge distance: minimum 1× embedment depth from concrete edge; preferred 1.5×
• Spacing between anchors: minimum 2× embedment depth between anchors; preferred 3×
• Spacing in groups: reduce design load when anchors are closer than 3× embedment apart

Chemical anchors have lower minimum edge distances because they don't generate expansion stress — typically 0.5× embedment from edge vs 1.5× for mechanical. This is why chemical anchors are preferred for edge work and post-tensioned slab perimeters.

Material Selection — Zinc vs Galvanised vs 316 Stainless

Anchor finish depends on the environment:

Galvanic corrosion warning: stainless steel anchors in galvanised steel fixtures (or vice versa) can accelerate corrosion of the less-noble metal in wet environments. For marine and coastal applications, match anchor material to fixture material — 316 anchor for 316 fixture, galv anchor for galv fixture. See our zinc plated vs galvanised guide for full detail.

AIMS Concrete & Masonry Anchor Range — Supply Ladder

Light fixings / plasterboard / hollow wall ($9-$15): Plasterboard Wall Plug #8 box of 100 ($9.95), Nail-In Anchor Nylon Body 304 SS Pin ($10.48), Drop-In Zinc Yellow M6 ($10.18), TX-CON Hex Slotted Anchor Screw ($11.64), Flush Head Sleeve Anchor 10mm ($11.65), Hollow Wall Anchor ($12.97), Universal Wall Plug ($14.16).

General fastening / commercial fit-out ($18-$45): Drop-In Pro Fire Rated M8 ($22.05), Drop-In Pro With Lip Fire Rated ($25.04), Xbolt Countersunk Zinc Yellow ($26.78), Bremick Stud Anchor 316 SS ($27.57), Xbolt Hex Flange Zinc Yellow ($32.60), Bremick Screw Anchor Hex Zinc ($33.28), Clawbolt Pro C1 & C2 M12 ($34.94), Clawbolt Pro C1 M12 ($46.58).

Heavy structural / fire-rated ($55-$120): Clawbolt Pro Fire Rated Larger Sizes ($60.56), Hex Flange Nut Sleeve Anchor 316 SS ($60.56), Inox World Drop In 316 SS ($74.28), Drop-in 316 Stainless Larger ($85.89), Countersunk Sleeve Anchor 316 SS ($88.42), Xbolt Coupler Screw MG ($118.87).

Chemical anchor stud kits ($4-$40 per stud, plus resin cartridge): Hobson Metric Stud Chemical Anchor Kit Grade 5.8 M8-M24 ($4.19-$39.01), Inox World Stud Anchor 316 SS ($51.14). Resin cartridges and dispensing guns sourced via supplier network.

Brand Reality — Stocked vs Source-on-Request

Selection Checklist

1. What's the substrate? Solid concrete = wedge / sleeve / drop-in / masonry screw. Hollow brick = chemical. Plasterboard = hollow wall anchor.
2. What's the load? Light (<10kg) = wall plug. Medium (10-50kg) = sleeve anchor or masonry screw. Heavy / structural = wedge / chemical with engineered spec.
3. Cracked or uncracked concrete? If structural / tension zone, assume cracked and use ETA Option 1 anchor.
4. Fire-rated? If yes, use C1 or C2 fire-rated anchor (Hobson Clawbolt Pro).
5. Environment? Indoor dry = zinc. Outdoor sheltered = galv. Coastal/marine = 316 stainless (Inox World).
6. Drill bit ready? Confirm correct masonry bit size for your anchor — see the drill size reference table.
7. Right drill? Rotary hammer for any concrete work. Hammer drill is only for soft mortar/brick.
8. Time-critical? Chemical anchor needs 2-24h cure depending on temperature. Mechanical anchor loads immediately.
9. Removable later? Masonry screw (hole reusable) or sleeve anchor (anchor stays, sleeve removable). Wedge anchor = permanent.
10. Edge distance check: minimum 1× embedment depth from concrete edge; 2× between anchors. Closer than this requires reduced design load.

Frequently Asked Questions

What size drill bit do I need for an M8 sleeve anchor?

An 8mm masonry drill bit for an 8mm-body sleeve anchor; a 10mm bit for a 10mm-body sleeve (the AIMS Hobson Flush Head Sleeve Anchor starts at 10mm body size). Always check the product packaging — the manufacturer prints the exact drill bit size required. The drill bit must match the sleeve outer diameter, not the thread size; sleeve anchors expand against the hole walls and need the close fit. See the drill size reference table for every common size.

What's the difference between a Dynabolt and a Trubolt?

Both are Ramset trademarks. Dynabolt® historically refers to Ramset's sleeve anchor range; Trubolt® refers to Ramset's wedge anchor range. The names are often used interchangeably in conversation, which causes confusion when ordering. The engineering categories are universal: sleeve anchor (full-length sleeve compression) vs wedge anchor (cone-and-clip expansion at the tip). AIMS doesn't sell Ramset; we sell the same anchor categories under Hobson and Bremick brands — Hobson Clawbolt Pro is our wedge anchor equivalent (Trubolt®-style), Hobson Flush Head Sleeve Anchor is our sleeve anchor equivalent (Dynabolt®-style).

Why does my dynabolt spin when I try to tighten it?

The most common cause is hollow substrate. Sleeve and wedge anchors require solid concrete or solid brick. If the anchor lands in a cavity behind the wall face, there's no surrounding material for the expansion sleeve to grip — the anchor rotates freely as you tighten. The fix is to switch to a chemical anchor with an anchor sleeve in the cavity zone, which fills the cavity with resin and bonds the stud through the wall face. Other causes: hole oversized (re-drilled too large), hole bottomed-out before anchor seated, or the anchor sleeve has been compressed before installation.

What's the difference between mechanical and chemical anchors?

Mechanical anchors (wedge, sleeve, drop-in, masonry screw) work by friction and physical interlock — the anchor expands or threads against the substrate. Chemical anchors work by adhesive bond — two-part resin glues the stud to the substrate along the full embedment depth. Mechanical is faster (instant load) but limited to solid substrates and generates expansion stress. Chemical handles hollow substrates, edge work, cracked concrete, and heavy loads — but requires cure time (2-24 hours depending on ambient temperature).

Can I use a hammer drill for concrete anchors?

For anchor work, use a rotary hammer (SDS-Plus or SDS-Max), not a regular hammer drill. The forum-validated consensus from Whirlpool Forums + Bunnings Workshop: regular hammer drills are largely a waste of time on concrete — they take forever, blunt bits quickly, and struggle past 10mm. A rotary hammer with pneumatic-piston percussion drills through concrete "as if drilling in pine" (direct AU forum quote). Budget rotary hammers start around $99 at Bunnings (Ozito) for occasional DIY work.

How long does a chemical anchor take to cure?

Cure time depends on ambient temperature and resin type. At 20°C: gel time 4-6 minutes (no further movement), full load capacity 4-6 hours. At 5°C: gel 15-20 minutes, full cure 24 hours. At 30°C+ AU summer: gel 2-3 minutes, full cure 2-3 hours. Vinylester resins cure faster than epoxy. See the full cure-time table in the Chemical Anchors section — always read your specific cartridge instructions and respect the listed times before applying load.

What is AS 5216 and does my anchor need to comply?

AS 5216:2018 (now also 5216:2021) is the AU standard for post-installed mechanical and chemical anchors in concrete. The NCC references it for structural anchorage. For domestic and light-commercial work the standard isn't strictly mandatory, but for any anchor in a structural load path, fire-rated assembly, engineered specification, or workplace OHS load case, AS 5216 compliance is non-negotiable. AS 5216 compliance is demonstrated via European Technical Assessment (ETA) prequalification — Option 1 (cracked + uncracked concrete) or Option 7 (uncracked only) are the two most common.

What's the difference between ETA Option 1 and ETA Option 7?

European Technical Assessment Option 1 means the anchor is qualified for both cracked and uncracked concrete. Option 7 means qualified for uncracked concrete only. For structural anchorage in tension zones (slab soffits, retaining wall faces, post-tensioned slab perimeters), engineers typically specify Option 1. For general fastening and machinery mounting in compression-loaded concrete, Option 7 is sufficient. The Hobson Clawbolt Pro range carries ETA Option 7. For Option 1, specialty supplier options (Hilti, Powers, Simpson Strong-Tie) are available via our trade network — source on request.

How deep should I drill for a wedge anchor?

Drill the anchor's specified embedment depth plus an extra 15mm for dust and chip accumulation. Skipping the extra depth means dust at the bottom prevents the anchor from seating to full embedment — the anchor will appear tight but won't reach rated capacity, and may pull out under load. For an M12 wedge anchor with 70mm embedment, drill 85mm deep. Mark the drill bit with tape for an accurate depth stop. See the drill size table for every common anchor size.

What anchor do I use in hollow brick?

Chemical anchor with an anchor sleeve, every time. Mechanical anchors (wedge, sleeve, drop-in) require solid material around the expansion zone; in hollow brick they spin or pull out under modest load. Forum-validated consensus from Bunnings Workshop, Homeone and Whirlpool: chemsets are "bulletproof" in hollow brick. The AIMS-stocked solution is the Hobson Metric Stud Chemical Anchor Kit Grade 5.8 plus a resin cartridge and an anchor sleeve sized to bridge the cavity. Total install cost from about $25 for a permanent fixing that holds 10-20 kN.

Can I reuse a hole if I pull an anchor out?

Wedge and sleeve anchors — no, the hole is damaged and oversized after removal; drill a new hole 50-75mm offset. Drop-in anchors — yes, the anchor stays in the concrete and you can re-thread a fresh bolt into the same female thread. Masonry screws (Hobson Xbolt) — yes, re-drive a fresh masonry screw of the same size into the existing hole. Chemical anchors — no, the resin bond is destroyed on removal; drill new hole. This is one practical advantage of drop-in anchors and masonry screws over wedge / sleeve / chemical.

What's the right anchor for hanging a TV on plasterboard?

For TVs (typically 10-30 kg), use spring-loaded toggle bolts or metal cavity anchors (molly bolts) — they grip the back face of the plasterboard and hold 20-35 kg each. Distribute the load over at least 4 anchors and use the TV bracket's specified anchor type. Avoid plastic wall plugs for anything above 5 kg; they only grip the front face of plasterboard and pull through under load. If you can hit a stud behind the plasterboard with a screw, that's always stronger than any plasterboard anchor.

What is fire-rated anchor C1 vs C2?

Fire ratings test the anchor's retention of load capacity under fire exposure (EN 1992-4 / EOTA TR 020). C1 rating is for fastenings where the anchor is not exposed to fire on multiple sides simultaneously (typical interior wall or ceiling fixing). C2 rating allows multi-sided fire exposure (more demanding test case). The Hobson Clawbolt Pro C1 & C2 Fire Rated is qualified to both ratings — appropriate for fire-rated wall and ceiling assemblies under NCC Section C. Specify fire-rated anchors any time the fastening is part of a fire-rated separation (e.g. door frames in fire walls, plant room services, fire dampers).

Why do I need a setting tool for a drop-in anchor?

Drop-in anchors hold by an internal cone that's driven downward into the anchor body, expanding the outer sleeve against the concrete. Without the matched setting tool, you can't drive the cone to the correct depth — the anchor won't properly expand and won't hold load. Each anchor size has a specific setting tool with a collar that hits the anchor body when the cone is fully seated. AIMS sells Metric Drop-In Setting Tools ($2.43+) and Drop-In Pro Setting Tool ETA ($10.83). Don't try to set a drop-in without one — the failure mode is silent (anchor looks set, fails under load).

What's the difference between sleeve anchor flush head and hex head?

Both are sleeve anchors — same expansion mechanism, same hole and substrate requirements. The difference is the head profile: flush head sits flush with the workpiece surface (used where a protruding head would interfere with cabinetry, brackets, or shelving), hex head has a standard hex nut profile (used where a spanner needs to reach the head for assembly). The hex flange nut variant uses the anchor's own thread plus a separate nut. Choose based on whether your fixture clears a hex head or needs flush mounting.

How do I clean the hole for a chemical anchor?

The forum-validated industry standard: blow 3 times, brush 3 times with the correct-size nylon brush, blow 3 more times. Use a hand pump bulb blower for hand-installed anchors; compressed air blow-off for larger jobs. The brush must be the correct diameter — too small and it doesn't reach the hole walls; too large and it won't enter. A dusty hole reduces chemical anchor pull-out strength by 50% or more — this is the single most common installation failure. Don't skip this step; it's the difference between an anchor that holds 20 kN and one that holds 9 kN.

For complete concrete and masonry fastening context, see our companion guides: bolt grade chart, zinc plated vs galvanised guide, stainless steel fasteners guide, fastener reference guide, metric vs imperial fasteners, drill bit types guide, choosing the right drill bit, magnetic drill guide.

Need help choosing the right anchor for a specific application? Browse the full anchors collection (40+ products), drop-in anchors and concrete screws / masonry screws. Call AIMS Industrial on (02) 9773 0122 or contact our trade team — we'll match the anchor to your substrate, load and compliance requirement, and source specialty options (Hilti, Powers, Simpson Strong-Tie, Wurth) through our supplier network.